Formation of PVA-SiO 2 hybrid films by Sol-Gel method: Effect of processing parameters and SiO 2 content on the structure and physico-chemical properties

Formation of PVA-SiO 2 hybrid films by Sol-Gel method: Effect of processing parameters and SiO 2 content on the structure and physico-chemical properties | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Formation of PVA-SiO 2 hybrid films by Sol-Gel method: Effect of processing parameters and SiO 2 content on the structure and physico-chemical properties Derradji Dadache, Farid Rouabah, Abdeslam Bencid, Brahim Barka This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6154062/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract In light of their unique properties and potential applications silicon dioxide (SiO 2 ) and polyvinyl alcohol (PVA) nanocomposites synthetized through the method known as sol-gel is gaining interest. For the first time, we investigated studied how processing variables like the number of HCl drops and the drying temperature influenced gel setting time. In the second time, tetraethoxysilane (TEOS) was hydrolysed and then condensed in a poly(vinyl alcohol) (PVA) solution to create organic–inorganic hybrid materials (PVA/SiO 2 ). With varying SiO 2 contents, the hybrid's optical properties and structure have been studied using infrared (FTIR) spectroscopy. For the hybrid, which includes 16% of SiO 2 , the thermal characteristics were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Si–O–C and Si–O–Si bond formation in the system was demonstrated using FTIR spectroscopy. TGA and DSC analysis showed that the hybrid films had better thermal stability and a lower melting temperature when compared to neat PVA films. At 190°C, PVA shows an intense endothermic peak, which indicates the melting point. Compared to neat PVA, the PVA/SiO 2 shows a less severe melting endothermic peak which is very weak and broad, discovered around 165°C. This suggests a decrease of 25°C. The hybrid film was also rendered more resistant to water absorption. Poly (vinyl alcohol) Silicon Dioxide Sol-Gel Method Hybrid Films Spectroscopic characterization Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Introduction Polyvinyl alcohol (PVA) and silicon dioxide (SiO 2 ) hybrid films have gained significant interest in recent years due to their excellent mechanical, thermal, and barrier properties. These properties make them suitable for a wide range of applications, including food packaging, optical coatings, optoelectronics, and hybrid membrane employed in desalination, biomaterials in medical applications and biomedical devices. The sol-gel method is a versatile and efficient technique for synthesizing PVA-SiO 2 hybrid films with desirable properties. The sol-gel method allows for the precise control of the structure and morphology of the resulting hybrid films by adjusting the processing parameters, such as pH, temperature, and SiO 2 content. Tirnakci et al. [ 1 ] studied the effects of temperature and the inclusion of nanomaterials into a PVA matrix on salt rejection and water flux. They arrived at their conclusion that the water pervaporation desalination results obtained using nano-SiO 2 -filled PVA membranes were encouraging for seawater desalination, and that the maximum salt rejection was 99.8% at a temperature of 30°C. Xie and colleagues [ 2 ] have been incorporated a novel kind of PVA/MA/silica hybrid membranes using solution casting and the sol-gel method. Their results of evaporation testing on the separation of an aqueous NaCl solution led researchers to the conclusion that such a type of hybrid membrane could potentially be employed in desalination. At 22° C salt rejection above 99.5% could be achieved. Due to its non-volatile nature, the salt rejection remained significant at different membrane thicknesses. Zhang et al. [ 3 ] studied the impact of polyvinyl alcohol fibers on the mechanical properties of nano-SiO 2 -reinforced geopolymer composites in an environment of complexity. Based to their findings, the PVA fiber dosage of 0.6% produced the greatest performance for the nano-SiO 2 -reinforced geopolymer composites (NSGPC). Organic–inorganic interpenetrating polymer network (IPN) materials have been synthesized by Quan et al. [ 4 ] using the hydrolysis and condensation of tetraethoxysilane (TEOS) in poly(vinyl alcohol) (PVA) solution. Si–O–C and Si–O–Si bond formation in the system has been demonstrated by FTIR spectroscopy, based on the results of the various characterisation techniques. When the correct amount of TEOS was applied, TEM showed a homogenous dispersion of silica in the PVA matrix. DSC and TGA showed that the hybrid films exhibited a greater glass transition temperature (Tg) and better thermal stability as compared to pure PVA films. The incorporation of SiO 2 on the optical conductivity (σopt) of PVA/CMC (carboxymethylcellulose) films induces a charge transfer between the molecules of the mixture and the SiO 2 following the formation of a network formed by the interstitial space between the chains of the PVA matrix loaded by the SiO 2 particles and the optical conductivity improves accordingly [ 5 ] . PVA-SiO 2 composite polymer coatings on wooden surfaces enhance the substrate's mechanical resilience and improve its water repulsion [ 6 ]. In addition, when compared to pure PVA, the tensile strength increased by a factor of 1.9 with a 20% by weight silica addition. Because of their enhanced mechanical strength and waterproofing qualities, such films can be employed as biomaterials in medical applications [ 6 ]. The mechanical properties of PVA-SiO 2 films have been shown to be significantly enhanced by Jia et al. when they produced the film with very low silica levels in the PVA matrix [ 7 ]. Polyvinyl alcohol (PVA) films for polymer optoelectronic applications have been prepared by Soliman et al. [ 8 ]. The SiO 2 nanoparticles were incorporated via a sonication technique followed by a solution casting method. The linear optical parameters (band gap, Urbach energy, refractive index, and extinction coefficient) have been examined. Their investigation led them to reach the conclusion that when the refractive index and extinction coefficient increased, the direct optical band gap and Urbach energy decreased as the amount of SiO 2 nanoparticles grew consecutively. Applications for polymer optoelectronics may make use of the obtained nanocomposite films. In an individual work, Zhao [ 9 ] synthesized poly(vinyl alcohol)/silica nano-composites hybrid membranes by co-hydrolyzing and co-condensing tetraethoxysilane (TEOS) and γ-glycidyloxypropyl trimethoxysilane (GPTMS) in an aqueous solution of poly(vinyl alcohol) (PVA). The findings showed that the addition of GPTMS significantly improved the organic phase's compatibility of the inorganic phase, as well as that an appropriate concentration of GPTMS generated nanoscale, uniformly distributed silica particles during the sol-gel process, enhancing the mechanical properties of hybrids. Zhang et al. [ 10 ] by chemically crosslinking in a saturated boric acid solution, a polyvinyl alcohol (PVA) hydrogel including precipitated silica (PSi) was developed. By chemical crosslinking in saturated boric acid solution, a polyvinyl alcohol (PVA) hydrogel comprising precipitated silica (PSi) was developed in a study by Zhang et al. [ 10 ]. It was found that PSi may accelerate the crosslinking process by consuming boric acid, and the intermolecular bonding between the PVA and PSi composite was confirmed. A sufficient PSi content may effectively demonstrate the hydrogel's mechanical properties and show that PSi acts as reinforcement on the hydrogel. The water absorption rate and equilibrium swelling rate may both be significantly increased by the addition of PSi, showing the greater capillary capacity for water absorption of PVA hydrogel. The PVA/PSi composite hydrogels' porous properties showed how the addition of PSi allowed the hydrogel to create several sizable pores that operated as pathways for microbiological metabolites. In addition, results from immobilizing activated sludge with PVA hydrogel for wastewater treatment demonstrated that the microorganism bioactivity of PVA immobilized beads could be enhanced above 2.0 wt%. The effects of SiO 2 nanoparticles on polyvinyl alcohol/carboxymethyl cellulose polymer blend films have been examined by Soliman [ 11 ]. The findings demonstrated that, as the proportion of SiO 2 increased, the blend film's transparency slightly decreased. Additionally, a redshift in the absorption edge was noted, suggesting that the optical bandgap energy decreased. Their enhanced film absorption and reduced transparency render them cheaper for use in UV-shielding applications. For the PVA/CMC/4 weight percent SiO 2 , the optical bandgap drops from 5.52 eV for pure PVA/CMC to 5.17 eV. The refractive index increases as matrix density rises, and this drop was caused by imperfections in the material. PVA/CMC/SiO 2 , the prepared current matrix, is believed to represent an intriguing possibility for optical applications. In a recent study Wu et al. [ 12] synthesized a hybrid material based on a PVA matrix doped with SiO 2 nanoparticles at different contents. They showed the growth of hydrophilicity, on the other hand the contact angle decreases with the increase in the SiO 2 content. As showed in several studies, adding SiO 2 to polyvinyl alcohol (PVA) improves the properties of the latter. Sabr et al. [ 13 ] synthesized a Poly (vinyl alcohol)/silica with various nano-SiO 2 content, to Improving Mechanical and Morphological Characteristics of this hybrid films, discovered that the PVA with 7wt % nano-SiO 2 content exhibited the highest properties. Bandyopadhyay et al [ 14 ] conducted an experiment where they combined Poly (vinyl alcohol) and silica at varying (TEOS) ratios. They observed an improvement in the water resistance and mechanical properties of PVA, and identified the optimal tensile strength at 40% TEOS or 16% of SiO 2 . Pingan et al [ 15 ] created an adhesive composed of 50% silica and 50% PVA, and explored the impact of the H 2 O/TEOS ratio on the material. They discovered that the PVA/silica composite exhibited outstanding mechanical properties and thermal stability while maintaining high transparency, surpassing that of neat PVA. They concluded that the ideal molar ratio of water to TEOS is 1, leading to a lower crystallinity and better dispersion. Hanh et al. [ 16 ] have developed a composite film made of polyvinyl alcohol (PVA) and glycerol, which includes nanosilica that had been extracted from bottom ash (BA) from solid waste from municipal incinerators. The findings show that the film with 1% silica has a 50% greater tensile strength compared to the film without silica. This represents an important increase in tensile strength. However, due to silica agglomeration within the polymer matrix, increased silica loadings lead to a reduction of mechanical properties. Yaseen et al. [ 17 ] have recently reported the synthesis, characterization, and application of a polymer-based ternary nanocomposite (CuO–SiO 2 /PVA) for the elimination of Nile Blue (NB) and Methylene Blue (MB) contaminants from wastewater, as well as researching its potential biological properties. This is carried out when combined with other inorganic compounds like CuO. It has been suggested that this particular composite might remove more bacteria and contaminants from wastewater. Phadkule et al. [ 18 ] investigated the impact of ZnO, SiO 2 , and ZnO-SiO 2 nanoparticle additions on the mechanical, structural, and water absorption properties of Polyvinyl Alcohol (PVA) films. For the PVA-ZnO, PVA-SiO 2 , and PVA-ZnO-SiO 2 films, the addition of nanoparticles improved the tensile strength of the composite films by 14%, 23%, and 66%, respectively, when compared to the pure PVA films. The study presents an easy approach for adjusting the properties of PVA mixed with nanoparticles of metal oxide for applications such as food packaging and medicine. With another technique, Nirwan et al. [ 19 ] investigated the synthesis of PVA/SiO 2 nanofibers by the electrospinning method for supercapacitor separators. They concluded that the silica concentration has an effect on the size of the nanofibers obtained, and increasing the silica concentration leads to a reduction in the diameter of the fibers. The best values obtained are 151% for electrolyte absorption and 60% for electrolyte retention, which shows the potential of PVA/silica nanofibers as an alternative material for supercapacitor separators. PVA/SiO 2 nanocomposites remain a highly sought-after subject of study as they have offered solutions to a wide variety of current problems facing humanity. According to the sol-gel method, it is possible to fabricate hybrid materials at low temperatures, which is crucial to preserve the characteristics of PVA while promoting a homogeneous dispersion of SiO 2 nanoparticles. In addition, this method offers the possibility to precisely modify the characteristics of the final material by changing the synthesis parameters such as pH, reagent concentration, and drying conditions. This work aims to synthesize and characterize a hybrid material based on poly(vinyl alcohol)/silica gel using the sol-gel process. The effect of processing parameters like HCl concentration and drying temperature on gel setting time has been extensively studied; the SiO 2 content was limited only for the spectroscopic analysis (FTIR and UV-VIS). However, the effect of thermal and physical properties was only taken into account for the PVA/SiO2 hybrid composite containing 16% SiO 2 . EXPERIMENTAL PART Materials Poly (vinyl alcohol) degree of polymerization = 1800, 98% hydrolyzed with Mw = 15000, Tetraethyl orthosilicate (TEOS) (98%, Mw = 208.33g/mol, d = 0.933g/ml), Ethanol (C 2 H 5 OH) (96% (v/v) Mw = 46.07 g/mol, d = 0.789g/ml), and hydrochloric acid (HCl) (38%, M = 36.46g/mol, d = 1.19g/ml), all of these materials were supplied by Sigma-Aldrich. Deionized water (DI) was used throughout all the experiments. All chemicals and materials were obtained and used as received without any further purification. Preparation of the Films In the first step, tetraethoxysilane (TEOS), ethanol, water was mixed and stirred for 15 min at 50°C. Volumes of components are listed in Table.1. and Table.2. A series of tubes tests containing 10ml from solution (TEOS + Ethanol + H 2 O) have been prepared. The mixtures were prepared by the addition of some drops of HCl catalyst at 50°C to the solution with constant stirring during 10 min. Every series of preparation of silica gel mixtures was put in oven and drying at different temperatures: 50, 70, 80, 90, 100, 110°C.The time of gelation was noted. Two types of films were prepared: neat PVA film and PVA/SiO 2 film. For the neat PVA film, 5 g of PVA was dissolved in 100 ml of deionized water (5 percent) by magnetic mixing and heating at 80°C for 1 hour until the mixture was homogeneous and viscous. The gel was then placed into a petri dish and allowed to solidify at room temperature for three days. For the PVA/SiO 2 film, different concentrations of tetraethyl orthosilicate (TEOS) ranging from 10 to 90% were dissolved in ethanol, deionized water, and hydrochloric acid at a molar ratio of 1:4:1:0.04 of TEOS/Ethanol/Water/HCl, respectively. The PVA solution was gradually added separately to each solution of TEOS and stirred for 1 hour at 60°C. The resulting mixture was poured into a Petri dish and allowed to solidify at room temperature for 3 days. The scheme of the PVA/TEOS interaction material is shown in Fig. 1 [ 21 ]. Characterization Several analytical techniques were employed to characterize the samples. The study by the XRD, DSC, TGA and water absorption tests have been only limited for the content of 16% of SiO 2 . In agreement with the work done by (Bandyopadhyay et al, Nakane K et al) [ 14 , 20 ] on the effect of silica gel content on the properties of PVA/SiO 2 hybrid materials that the best SiO 2 content is 16% by weight. However, the spectroscopic study of PVA/SiO 2 hybrid films by FTIR and UV-VIS spectroscopy has been used for different Sio2 contents (10, 20, 30, 40,50, 60,70, 80 and 90%). Fourier Transform Infrared Spectroscopy (FT-IR) was used to record the infrared spectra, using a Perkin Elmer FTIR Spectrum 1000 spectrophotometer in transmission mode at room temperature. The samples underwent 32 scans, and X-ray Diffraction (XRD) measurements were conducted using a Phillips X'PERT Pro diffractometer with a CuKα radiation source, while UV-VIS Spectrophotometry was carried out using a Perkin Elmer 4B spectrophotometer to record the absorption and transmission spectra of the samples in the range of 200–800 cm-1. Thermogravimetric analysis (TGA) was carried out in an N 2 atmosphere using a Mettler Toledo Star System, while Differential Scanning Calorimetry (DSC) was performed using a Perkin-Elmer differential scanning calorimeter. The water absorption rate of the samples was determined using the ASTM-D570-81 procedure, and the water uptake was calculated using Eq. 1 and plotted against time, where W represents the water uptake, m 0 is the initial dry weight of the film, and m t is the dry weight of the swollen film. $$\:\mathbf{W}\left(\mathbf{\%}\right)=\left[\frac{{\varvec{m}}_{\varvec{t}}-{\varvec{m}}_{0}}{{\varvec{m}}_{0}}\right].100\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:$$ 1 RESULTS AND DISCUSSION Processing Parameters In the present study, we have attempts, in a first time so study some parameters who affect the rate of gelation during formation of silica gel like the acid content and the drying temperature. Moreover, by using a purely aqueous medium the use of expensive and very often toxic solvents has been avoided. In a second time, the preparation of PVA/silica hybrid from the optimum conditions of reaction of condensation. The synthesis of PVA/SiO 2 hybrids typically involves the sol-gel process, where tetraethyl orthosilicate (TEOS) is hydrolysed and condensed in the presence of PVA. Hydrochloric acid (HCl) is commonly used as a catalyst in this process to control the rate of hydrolysis and condensation of the silica precursor, which ultimately affects the gelation time or gel setting time of the resulting PVA/SiO 2 hybrid The gelation time, or gel setting time, is a critical parameter in this process, and both the concentration of HCl and the temperature of the solution can influence it. The time of gelation as function of drying temperature is shown in Fig. 2 for different drops of HCl. As can be seen, as the number of drops increase, the time of gelation decrease significantly. This decrease is more important as the number drop of HCL is important. However, at drying temperature 110° C the times gelification of different mixtures become almost equals. As the number of drops of HCl increases, the acidity of the solution increases, which accelerates the hydrolysis of TEOS, leading to faster formation of silanol groups (Si-OH). These silanol groups subsequently undergo condensation to form Si-O-Si bonds, resulting in the formation of a silica network within the PVA matrix. A higher concentration of HCl generally leads to a shorter gelation time, as the reactions proceed more rapidly in a highly acidic environment. The time of gelation as a function of the acidity of solution for different drying temperatures is given in Fig. 3 . As can be seen if the number drops of HCl increase, the time of gelation decrease. This decrease is very important at drying temperature 110°C.It means that The PH solution has little effect on the reaction of polycondensation. The addition of HCl in different amounts influences the pH of the sol, which directly affects the kinetics of the hydrolysis and condensation reactions of TEOS. A higher concentration of HCl (i.e., more drops) typically results in a faster gelation process because it accelerates the formation and condensation of silanol (Si-OH) groups. However, an excess of HCl can cause rapid and uneven gelation, leading to potential issues such as phase separation or the formation of non-uniform silica networks. The combination of HCl concentration and drying temperature must be carefully optimized to achieve desirable gelation and drying outcomes. A higher number of HCl drops might require lower drying temperatures to prevent rapid evaporation and potential defects. Conversely, lower HCl concentrations might allow for higher drying temperatures without compromising the uniformity and stability of the hybrid material. Moderate drying temperatures (50 and 100°C) strike a balance between the slow evaporation at low temperatures and the rapid drying at high temperatures. This range allows for a more efficient removal of solvents while still maintaining a controlled drying process. The PVA/SiO 2 hybrid tends to exhibit good mechanical properties and a stable structure, with reduced drying time compared to lower temperatures. Higher drying temperatures (> 100°C) lead to rapid solvent evaporation and faster densification of the silica network. While this can shorten the overall processing time, it also increases the risk of defects such as cracks, due to uneven shrinkage or thermal stresses. High temperatures can also cause the PVA matrix to undergo changes such as thermal degradation or excessive shrinkage, which can negatively affect the mechanical properties of the hybrid material. Structure and Morphology of the Hybrid Films Fourier Transform Infrared Spectroscopy To investigate the existence of specific chemical groups in the hybrid materials, Fourier Transform Infrared Spectroscopy (FT-IR) was employed. Figure 4 shows the FTIR spectrum of PVA and the hybrid PVA/SiO 2 mixtures at different percentages of TEOS. From this figure there is the appearance of symmetrical and asymmetrical elongation vibrations of the C-H bond of neat PVA and PVA/SiO 2 mixtures. The relative intensity of the peaks around 3250 cm-1 was lower for the samples containing the SiO 2 than that of the neat PVA sample; it decreases with increasing SiO 2 content, indicating that some of the hydroxyl groups of PVA involved in the condensation reaction with silanol groups (Si–OH) in silica sol, forming covalently bonded cross-links between organic groups and silica. However, the peak increases when the silica content is 60% by weight. This indicates that the SiO 2 sol is redundant. Moreover, the strong band at 1086 cm –1 is attributed to the C-C groups stretching in the crystalline phase of the PVA matrix. The intensity of this band increases as the degree of crystallinity increases. It is to be noted that this band of crystallinity became flattered in the sample contain silica, which indicates the diminution of crystallinity and that the silica/PVA network has successfully been formed. This peak at 1086 cm -1 were wider for the samples containing the SiO 2 . It is also noted that the intensity of this peak group decreases with the increase in the silica content. This can be attributed to the adsorption peak overlap of Si–O–C and Si–O–Si due to the condensation reaction between Si–OH groups and C–OH groups of PVA. i.e. many silanol groups condensed with the hydroxyls on the PVA chain to form a Si–O–PVA–O–Si bridge. The presence of Si–O–C and Si–O–Si bonds confirmed the existence of a chemical bond between the organic groups and the silica. X-Ray DiffractionAnalysis Figure 5 presents the X-ray diffraction (XDR) of the hybrid films. X-ray diffraction (XRD) is a powerful technique for studying the crystalline structure of polymers like polyvinyl alcohol (PVA) and its composites. Typically, the neat PVA exhibits a broad diffraction peak around 2θ = 19.5°, which corresponds to the (101) plane of its orthorhombic crystalline structure. However, if amorphous SiO 2 is incorporated, no distinct crystalline peaks of SiO 2 will be observed, the peak becomes significantly broader and shifts in the sample containing silica. These results indicate that the presence of SiO 2 in hybrid films has an impact on the crystallinity of PVA. When SiO 2 (silica) is introduced into the PVA matrix, the XRD pattern of the composite (PVA/SiO2) shows significant changes. The presence of SiO 2 nanoparticles, which are typically amorphous, leads to a reduction in the intensity of the PVA diffraction peaks. This reduction is due to the disruption of the regular packing of PVA chains, which lowers the overall crystallinity of the composite. In some cases, the broadening of peaks can also be observed, indicating a reduction in the size of crystalline domains. The broadening of peaks and the presence of a more pronounced amorphous halo are also observed, which can be attributed to the distribution of SiO 2 nanoparticles within the PVA matrix. The interaction between PVA and SiO 2 , likely through hydrogen bonding, hinders the crystallization of PVA, leading to a more amorphous structure in the composite. These changes in the UV-Vis spectra are crucial for tuning the optical properties of PVA/SiO 2 hybrid films for specific applications, such as in optical coatings, sensors, and packaging materials. Thermal Properties Thermogravimetric Analysis The thermogravimetric curves of neat PVA and PVA/SiO 2 composites are shown in Fig. 7 According to Fig. 6 , the thermal degradation of neat PVA demonstrates three major weight loss regions. The initial region occurs at temperatures ranging from 20–100°C with a maximum weight loss temperature at Tmax, step1 = 95°C. This region can be attributed to the evaporation of free and bound water molecules, resulting in a small weight loss of 20%. The second region, which exhibits the maximum decomposition rate, takes place between 224 to 486°C and is estimated to result in a weight loss of 15%. This weight loss is due to the degradation of the (-OH) side group, causing the formation of a polyene at Tmax, step2 = 270°C. The third region, which occurs in the 410–450°C range with Tmax, step3 = 430°C, corresponds to the decomposition of the main chain of PVA polymer (cleavage of C–C backbone) which is also called carbocation or carbonation. This last step leads to a weight loss of 91 wt.% at 600°C, resulting in a total residue of 9%. After introducing silica to the PVA matrix, the thermal stability of the PVA/SiO 2 membranes is enhanced, as shown in Fig. 6 . In this case, the PVA/SiO 2 thermogram reveals four weight-loss regions with slow and gradual degradation. This may be attributed to the loss of the crystalline structure, which shifts to a more amorphous state due to hydrogen bonding between PVA chains and silanol ends of the silica. This explanation is supported by the FT-IR and DSC results, as discussed earlier. The first weight loss is estimated at 6%, and this is due to the silanol groups and their self-condensation reaction, resulting in the removal of residual solvent molecules (water and ethanol) at temperatures of 30–170°C. The remaining weight loss regions occur in the temperature ranges of 170–390°C, 390–490°C, and 490–690°C with maximum weight loss temperatures of 120, 330, 455, and 590°C, respectively. These temperatures indicate the degradation of hydroxyl groups with other organic residues of PVA and silica networks. The final residual weight corresponds to 76.9–83.6% of the global weight, resulting in a total residue of 20%. Overall, it can be concluded that incorporating a silica network into the PVA matrix enhances the thermal stability of the films. This suggests that there is an improvement in the thermal stability of PVA/SiO 2 as the content of TEOS increases. Differential Scanning Calorimetry The analysis of thermal properties of materials is a crucial aspect, and DSC is a significant technique for this purpose. In this study, the DSC analysis was employed to measure the crystallization and melting temperatures (Tc, Tm) of the samples. DSC curves of neat PVA and PVA/SiO 2 are presented in Fig. 7 (a, b). The curves depict both exothermic and endothermic reactions. PVA shows a sharp endothermic peak at 190°C, indicating the melting point (Fig. 7 a). Conversely When SiO 2 is incorporated into PVA at a concentration of 16%, the DSC curve of the resulting composite film shows modifications compared to neat PVA. The presence of SiO 2 nanoparticles can influence the thermal transitions of PVA. The melting peak in the DSC curve might be altered by the addition of SiO 2 . The peak may become broader or shift slightly due to changes in the crystalline structure of PVA. The degree of crystallinity is often reduced in the presence of SiO 2 , leading to a less distinct melting peak. The PVA/SiO 2 exhibits less sharp melting endothermic peak very weak and broad, observed at around 165°C, indicating a decrease of 25°C compared to neat PVA. In contrast, an exothermic peak corresponding to the crystallization region (Tc) is observed for neat PVA at a temperature of 112°C (Fig. 7 c), but it is absent in PVA/SiO 2 . This lack of crystallization is caused by the crosslinking reaction between PVA chains and the silanol ends of silica. Physical Properties 3.2.1 Water absorption. Figure 8 , shows the level of water absorption for Neat PVA and PVA/SiO 2 composite films. Silicon dioxide (SiO 2 ) is inherently hydrophilic due to the presence of surface hydroxyl groups, which can readily interact with water molecules. However, in its bulk form or as a dense film, neat SiO 2 exhibits low water absorption. This is because the tightly packed structure and strong Si-O-Si bonds limit the diffusion of water into the material. Any water absorbed by neat SiO 2 is usually confined to the surface or to the first few molecular layers, and the overall water absorption remains minimal. When SiO 2 was incorporated into PVA to form a hybrid film with 16% SiO 2 , the water absorption behavior of the composite changes. The presence of SiO 2 can reduce the overall water absorption of the PVA matrix by disrupting the continuous network of hydroxyl groups. SiO 2 particles can create a more tortuous path for water molecules, reducing the rate and extent of water uptake. Additionally, the interaction between PVA and SiO 2 , such as through hydrogen bonding, can further limit the availability of free hydroxyl groups in PVA to interact with water. The hydroxyl groups present in PVA make it highly susceptible to water absorption. However, the addition of silica to the PVA matrix results in a significant decrease in water absorption compared to neat PVA. This decrease can be attributed to the possible hydrogen bonding between silica and PVA, which reduces the volume of water absorbed by the polar hydroxyl groups. These observations suggest that these hybrid films could serve as water perm selective membranes. Moreover, given that PVA is currently employed as a biomaterial, these novel hybrid materials could potentially find use in biomedical applications. Conclusions As it sums up, in order to achieve the appropriate gelation and drying achievements, the combination of HCl concentration and drying temperature must be carefully adjusted the first time. Low drying temperatures can be required for a greater number of HCl drops in order to prevent rapid evaporation and possible imperfections. On the contrary hand, low HCl concentrations may allow greater drying temperatures without affecting the hybrid material's stability and homogeneity. In the second time the PVA-SiO 2 hybrid films synthesized using the sol-gel method has been successfully developed with the variation of processing parameters and SiO 2 content. The produced composite PVA/SiO 2 was evaluated for its structural, thermal, spectroscopic, and physical properties through a number of analysis techniques, including FTIR, DRX, DSC, TGA, and water uptake capacity. Based on the obtained findings, it may be concluded that: The FT-IR research verified that hydrogen bonds were formed between PVA and SiO 2 at varying concentrations of SiO 2 , signifying a successful interaction between the two components. A chemical connect among the organic groups and the silica has been demonstrated by the presence of Si–O–C and Si–O–Si bonds. The UV-VIS analysis revealed that the optical transmittance of the composite films improved as the SiO 2 content increase for an identical different SiO 2 concentration. Furthermore, the XRD examination revealed that the addition of nanoparticles led to the creation of a semi-crystalline morphology for the composite PVA/SiO 2 containing 16% of SiO 2 . The intensity of the PVA diffraction peaks diminishes when SiO 2 nanoparticles, which are usually amorphous, are added. The hybrid films' thermal stability increased, depending to the TGA analysis. It has been found that the inclusion of SiO 2 enhanced the hybrid films' ability to absorb water for the same composite. These results imply that the structure and physicochemical characteristics of the hybrid films are significantly affected by the inclusion of SiO 2 nanoparticles to the PVA matrix, thereby rendering the films suitable for a range of uses, such biomedical devices, packaging, and sensors. The mechanical and biological properties of these hybrid films can be researched subsequently. Declarations Conflicts of interest The authors declare no conflict of interest Funding no funding Author Contribution Derradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka conceived of the presented idea Derradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka carried out the experiment. Derradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka wrote the main manuscript text . Derradji Dadache and Farid Rouabah prepared figures 1-8 and tables 1-2. All authors discussed the results and contributed to the final manuscript. Authors’ contributions are equal. Acknowledgments The authors would like to thank the Ministry of Higher Education and Scientific Research (MESRS) and the General Directorate of Scientific Research and Technological Development (DGRSDT) – Algeria References Tirnakci B, Salt Y (2021) preparation and characterization of pva-sio2 nanocomposite membranes for seawater desalination by pervaporation. Chem Ind Chem Eng Qtly. https://doi.org/10.2298/CICEQ200505037T Xie Z, Hoang M, Duong T, Ng D, Dao B, Gray S (2011) Sol–gel derived poly(vinyl alcohol)/maleic acid/silica hybrid membrane for desalination by pervaporation. J Memb Sci. https://doi.org/10.1016/j.memsci.2011.08.036 Zhang P, Wang C, Guo Z, Hong J, Wang F (2023) Effect of polyvinyl alcohol fibers on mechanical properties of nano-SiO 2 -reinforced geopolymer composites under a complex environment. Nanotechnol Rev. https://doi.org/10.1515/ntrev-2023-0142 Quan Fy, Chen LL, Xia YZ, Ji Q (2009) Structure and Properties of PVA/SiO2 Interpenetrating Polymer Network Materials Prepared by the Sol–Gel Method. Poly Poly Compos. https://doi.org/10.1177/096739110901700205 Soliman TS, Abouhaswa AS (2020) Synthesis and structural of Cd0.5Zn0.5F2O4 nanoparticles and its influence on the structure and optical properties of polyvinyl alcohol films. J Mater Sci: Mater Elec. https://doi.org/10.1007/s10854-020-03512-6 Liu F, Wang S, Zhang M, Ma M, Wang C, Li J (2013) Improvement of mechanical robustness of the super hydrophobic wood surface by coating PVA/SiO2 composite polymer. Appl Surf Sci. https://doi.org/10.1016/j.apsusc.2013.05.043 Jia X, Li Y, Cheng Q, Zhang S, Zhang (2007) Preparation and properties of poly (vinyl alcohol)/silica nanocomposites derived from copolymerization of vinyl silica nanoparticles andvinyl acetate. Eur Poly J. https://doi.org/10.1016/j.eurpolymj.2007.01.019 Soliman TS, Sergey A, Shivkov V, Elkalashy IS (2020) Structural, thermal, and linear optical properties of SiO2 nanoparticles dispersed in polyvinyl alcohol nanocomposite films. Poly Compos. https://doi.org/10.1002/pc.25623 Zhao YN (2013) Preparation of poly(vinyl alcohol)/silica nanocomposties by sol-gel method. e-Polymers. https://doi.org/10.1515/epoly.2013.2013.1.115 Zhang Y, Ye L Structure and property of polyvinyl alcohol/precipitated silica composite hydrogels for microorganism immobilization. Compos:, Part B (2014) http://dx.doi.org/10.1016/j.compositesb.2013.09.015 Soliman TS (2024) Effects of Nanoparticles on Polyvinyl Alcohol/Carboxymethyl Cellulose Polymer Blend Films’ Structural, Wettability, Surface Roughness, and Optical Characteristics. Adv Poly Tech. https://doi.org/10.1155/2024/3623198 Wu G, Yang Y, Lei Y, Fu D, Li Y, Zhan Y, Zhen J, Teng M (2020) Hydrophilic nano-/PVA-based coating with durable antifogging properties. J Coat Tech Res. https://doi.org/10.1007/s11998-020-00338-z Sabr O, Hussein A, Obaid M (2021) Preparation and evalution water resistance, mechanical and morphological characteristics of PVA/SiO2 nanocomposites for food industry applications Digest. J Nanomater Biostruct. http://dx.doi.org/10.15251/DJNB.2021.162.733 Bandyopadhyay A, De Sarkar M, Bhowmick AK (2005) Poly(vinyl alcohol)/silica hybrid nanocomposites by sol-gel technique: Synthesis and properties. J Mater Sci. https://doi.org/10.1007/s10853-005-4417-y Pingan H, Mengjun J, Yanyan Z, Ling H (2017) A silica/PVA adhesive hybrid material with high transparency, thermostability and mechanical strength. RSC Adv. https://doi.org/10.1039/C6RA25579E Hanh PTH, Suwunwong T, Chantrapromma C, Choto P, Thanomsilp C, Phoungthong K (2024) Preparation and characterization of polyvinyl alcohol (PVA)-glycerol composite films incorporating nanosilica from municipal solid waste incinerator bottom ash. Heliyon. https://doi.org/10.1016/j.heliyon.2024.e25963 Yaseen M, Khan A, Humayun M, Bibia S, Farooq S, Bououdina M, Ahmad S (2024) Fabrication and characterization of CuO–/PVA polymer nanocomposite for effective wastewater treatment and prospective biological applications. Gr Chem Lett Rev. https://doi.org/10.1080/17518253.2024.2321251 Phadkule S, Navin K, Nigrawal A, Ball R, Kurchania R (2022) Effects of ZnO and SiO 2 Nanoparticle Additions on the Structural, Water Absorption and Mechanical Properties of Polyvinyl Alcohol (PVA) Films'. Nano Hybrids and Composites. https://doi.org/10.4028/p-9y7z3x Nirwan M, Setyawan H (2021) Synthesis of PVA/SiO2 nanofibers by electrospinning method for supercapacitor separators. W Widiyastuti - IPTEK J Proc Ser. http://dx.doi.org.10.12962/j23546026.y2020i6.11119 Nakane K, Yamashita T, Iwakura K, Suzuki F (1999) Properties and structure of poly (vinyl alcohol)/silica composites. J Appl Poly Sci. https://doi.org/10.1002/(SICI)1097-4628(19991003)74:13.0.CO;2-N Dodda JM, Bělský P, Chmelař J, Remiš T, Tomáš M, Kullová L, Kadlec J (2015) Comparative study of PVA/SiO2 and PVA/SiO2/glutaraldehyde (GA) nanocomposite membranes prepared by single-step solution casting method. J Mater Sci. https://doi.org/10.1007/s10853-015-9206-7 Here are the figures captions with a brief title next to each one Tables Table 1 Volume of used sol systems Sol type Volume of TEOS (ml) Volume of C 2 H 5 OH Volume of H 2 O (ml) Drops of HCl Polyvinyl alcohol (PVA)(g) Sol (1) = GS 22.6 60 10 Varie from 10 to 17 drops 0 Sol (2) = P 40 5 Table 2 Compositions and preparation of the hybrid solutions P: Neat PVA, PS: PVA/SiO 2 . Sample PVA (W %) TEOS (wt %) Silica (W %) TEOS (wt %) in Solution PVA (wt %) in the solution silica: PVA ratio in solution (by wt) H 2 O/TEOS (mol) ratio HCL/TEOS (mol ) ratio Appearance of the films P 100 0 0 0 5 0:1 0 0 Transparent PS1 90 10 4 1.125 4.5 0.25: 2.25 1 0.01 Transparent PS2 80 20 8 2.25 4 0.5: 2 1 0.02 Transparent PS3 70 30 12 3.375 3.5 0.75: 1.75 1 0.03 Transparent PS4 60 40 16 4.5 3 1:1.5 1 0.04 Transparent PS5 50 50 20 5.625 2.5 1.25: 1.25 1 0.05 Transparent PS6 40 60 24 6.75 2 1.5: 1 1 0.06 Transparent PS7 30 70 28 7.875 1.5 1.75: 0.75 1 0.07 Transparent PS8 20 80 32 9 1 2: 0.5 1 0.08 Transparent PS9 10 90 36 10.125 0.5 2.25: 0.25 1 0.09 Transparent PS10 0 100 40 11.25 0 1: 0 1 0.10 Transparent Additional Declarations No competing interests reported. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-6154062","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":456387551,"identity":"73d7fedc-5bb9-47df-8827-c781f53e1876","order_by":0,"name":"Derradji Dadache","email":"","orcid":"","institution":"University of Bordj Bou Arreridj","correspondingAuthor":false,"prefix":"","firstName":"Derradji","middleName":"","lastName":"Dadache","suffix":""},{"id":456387552,"identity":"01eb7a52-c269-4837-8aff-90da49dc5391","order_by":1,"name":"Farid Rouabah","email":"data:image/png;base64,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","orcid":"","institution":"Ferhat Abbas University","correspondingAuthor":true,"prefix":"","firstName":"Farid","middleName":"","lastName":"Rouabah","suffix":""},{"id":456387553,"identity":"c5604d44-faa4-41a2-964c-4c9ba9b37056","order_by":2,"name":"Abdeslam Bencid","email":"","orcid":"","institution":"Research Center in Industrial Technologies CRTI","correspondingAuthor":false,"prefix":"","firstName":"Abdeslam","middleName":"","lastName":"Bencid","suffix":""},{"id":456387554,"identity":"2eb16fdf-39a6-4fd4-a55b-86774a9dd4c5","order_by":3,"name":"Brahim Barka","email":"","orcid":"","institution":"Ferhat Abbas University","correspondingAuthor":false,"prefix":"","firstName":"Brahim","middleName":"","lastName":"Barka","suffix":""}],"badges":[],"createdAt":"2025-03-04 11:38:15","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6154062/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6154062/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":82768301,"identity":"c273ce5b-bb34-493c-a579-13d388b4b171","added_by":"auto","created_at":"2025-05-15 05:30:32","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":30801,"visible":true,"origin":"","legend":"\u003cp\u003eScheme of the interaction between TEOS and PVA.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eIllustration of the interaction between tetraethyl orthosilicate (TEOS) and polyvinyl alcohol (PVA).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/34bbf8fbba13eec0e7cadbbc.png"},{"id":82766916,"identity":"4311e99c-20c9-4482-9e3e-aba877af4e15","added_by":"auto","created_at":"2025-05-15 05:05:40","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":12564,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in gel setting time as a function of the number of drops of HCl.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eGel setting time for different numbers of HCl drops: A: 10, B: 11, C: 12, D: 13, E: 14, F: 15, G: 16, H: 17.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/0765ce78fcf3a01acb86ec24.png"},{"id":82766917,"identity":"357444a8-b8b1-40c3-9d56-b7b31f43b77d","added_by":"auto","created_at":"2025-05-15 05:05:40","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":9337,"visible":true,"origin":"","legend":"\u003cp\u003eVariation in gel setting time depending on the drying temperature.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eEffect of drying temperature on gel setting time: A: 50°C, B: 70°C, C: 80°C, D: 90°C, E: 100°C, F: 110°C.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/4785da97dcdedfd243556c49.png"},{"id":82766930,"identity":"900a691e-38a1-4a5a-9f71-a1e9316ce3d4","added_by":"auto","created_at":"2025-05-15 05:05:41","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":11469,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra of neat PVA and hybrid PVA/SiO2 mixtures at different percentages of SiO2.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eFourier-transform infrared (FTIR) spectra of PVA and hybrid PVA/SiO2 mixtures at varying SiO2 concentrations: A: Neat PVA, B: PVA + 10% SiO2, C: PVA + 20% SiO2, D: PVA + 30% SiO2, E: PVA + 40% SiO2, F: PVA + 50% SiO2, G: PVA + 60% SiO2, H: PVA + 70% SiO2.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/b8e11b4acc3152b2c66e979a.png"},{"id":82766920,"identity":"bd319253-4320-45ad-8e39-35bb45f6deca","added_by":"auto","created_at":"2025-05-15 05:05:41","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":15478,"visible":true,"origin":"","legend":"\u003cp\u003eX-ray patterns of hybrid films containing 16% SiO2.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eX-ray diffraction (XRD) patterns of hybrid films with 16% SiO2.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure5.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/89922ee9f0bea4deec61a923.png"},{"id":82766952,"identity":"a8ddf4ff-0953-4b1b-b568-87b5c3f4275e","added_by":"auto","created_at":"2025-05-15 05:05:42","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":10544,"visible":true,"origin":"","legend":"\u003cp\u003eTGA thermograms of Neat PVA and PVA/SiO2 containing 16% SiO2.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eThermogravimetric analysis (TGA) curves for neat PVA and PVA/SiO2 films with 16% SiO2.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure6.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/cc13a7c518be1b8d94bb0109.png"},{"id":82766919,"identity":"74be288b-77c4-4356-a424-a538062650c4","added_by":"auto","created_at":"2025-05-15 05:05:40","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":13481,"visible":true,"origin":"","legend":"\u003cp\u003e\u003cstrong\u003e(a, b)\u003c/strong\u003e: DSC curves of neat PVA and PVA/SiO2 containing 16% SiO2.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003e(a) Melting peaks for neat PVA and PVA/SiO2; (b) Crystallization peaks for neat PVA and PVA/SiO2 with 16% SiO2.\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure7.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/99f3a0e496ee53df914d4e49.png"},{"id":82766922,"identity":"752b7e50-9af9-4f1a-9922-a33cc584ecd8","added_by":"auto","created_at":"2025-05-15 05:05:41","extension":"png","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":12100,"visible":true,"origin":"","legend":"\u003cp\u003eWater absorption of hybrid films.\u003c/p\u003e\n\u003cp\u003e\u003cem\u003eWater absorption properties of neat SiO2 (S), neat PVA (P), and PVA/SiO2 films with 16% SiO2 (PS).\u003c/em\u003e\u003c/p\u003e","description":"","filename":"figure8.png","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/ba618223b37304b97c073b33.png"},{"id":83638928,"identity":"f0ea15fb-ca75-42ef-96b6-1485331d53a8","added_by":"auto","created_at":"2025-05-30 02:31:49","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":918600,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6154062/v1/f49e91a2-88f6-4cf7-ba63-9f0ef5a20398.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Formation of PVA-SiO 2 hybrid films by Sol-Gel method: Effect of processing parameters and SiO 2 content on the structure and physico-chemical properties","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePolyvinyl alcohol (PVA) and silicon dioxide (SiO\u003csub\u003e2\u003c/sub\u003e) hybrid films have gained significant interest in recent years due to their excellent mechanical, thermal, and barrier properties. These properties make them suitable for a wide range of applications, including food packaging, optical coatings, optoelectronics, and hybrid membrane employed in desalination, biomaterials in medical applications and biomedical devices. The sol-gel method is a versatile and efficient technique for synthesizing PVA-SiO\u003csub\u003e2\u003c/sub\u003e hybrid films with desirable properties. The sol-gel method allows for the precise control of the structure and morphology of the resulting hybrid films by adjusting the processing parameters, such as pH, temperature, and SiO\u003csub\u003e2\u003c/sub\u003e content. Tirnakci et al. [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e] studied the effects of temperature and the inclusion of nanomaterials into a PVA matrix on salt rejection and water flux. They arrived at their conclusion that the water pervaporation desalination results obtained using nano-SiO\u003csub\u003e2\u003c/sub\u003e-filled PVA membranes were encouraging for seawater desalination, and that the maximum salt rejection was 99.8% at a temperature of 30\u0026deg;C. Xie and colleagues [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e] have been incorporated a novel kind of PVA/MA/silica hybrid membranes using solution casting and the sol-gel method. Their results of evaporation testing on the separation of an aqueous NaCl solution led researchers to the conclusion that such a type of hybrid membrane could potentially be employed in desalination. At 22\u0026deg; C salt rejection above 99.5% could be achieved. Due to its non-volatile nature, the salt rejection remained significant at different membrane thicknesses.\u003c/p\u003e \u003cp\u003eZhang et al. [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e] studied the impact of polyvinyl alcohol fibers on the mechanical properties of nano-SiO\u003csub\u003e2\u003c/sub\u003e-reinforced geopolymer composites in an environment of complexity. Based to their findings, the PVA fiber dosage of 0.6% produced the greatest performance for the nano-SiO\u003csub\u003e2\u003c/sub\u003e-reinforced geopolymer composites (NSGPC).\u003c/p\u003e \u003cp\u003eOrganic\u0026ndash;inorganic interpenetrating polymer network (IPN) materials have been synthesized by Quan et al. [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] using the hydrolysis and condensation of tetraethoxysilane (TEOS) in poly(vinyl alcohol) (PVA) solution. Si\u0026ndash;O\u0026ndash;C and Si\u0026ndash;O\u0026ndash;Si bond formation in the system has been demonstrated by FTIR spectroscopy, based on the results of the various characterisation techniques. When the correct amount of TEOS was applied, TEM showed a homogenous dispersion of silica in the PVA matrix. DSC and TGA showed that the hybrid films exhibited a greater glass transition temperature (Tg) and better thermal stability as compared to pure PVA films. The incorporation of SiO\u003csub\u003e2\u003c/sub\u003e on the optical conductivity (σopt) of PVA/CMC (carboxymethylcellulose) films induces a charge transfer between the molecules of the mixture and the SiO\u003csub\u003e2\u003c/sub\u003e following the formation of a network formed by the interstitial space between the chains of the PVA matrix loaded by the SiO\u003csub\u003e2\u003c/sub\u003e particles and the optical conductivity improves accordingly [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e] .\u003c/p\u003e \u003cp\u003ePVA-SiO\u003csub\u003e2\u003c/sub\u003e composite polymer coatings on wooden surfaces enhance the substrate's mechanical resilience and improve its water repulsion [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. In addition, when compared to pure PVA, the tensile strength increased by a factor of 1.9 with a 20% by weight silica addition. Because of their enhanced mechanical strength and waterproofing qualities, such films can be employed as biomaterials in medical applications [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. The mechanical properties of PVA-SiO\u003csub\u003e2\u003c/sub\u003e films have been shown to be significantly enhanced by Jia et al. when they produced the film with very low silica levels in the PVA matrix [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e].\u003c/p\u003e \u003cp\u003ePolyvinyl alcohol (PVA) films for polymer optoelectronic applications have been prepared by Soliman et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles were incorporated via a sonication technique followed by a solution casting method. The linear optical parameters (band gap, Urbach energy, refractive index, and extinction coefficient) have been examined. Their investigation led them to reach the conclusion that when the refractive index and extinction coefficient increased, the direct optical band gap and Urbach energy decreased as the amount of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles grew consecutively. Applications for polymer optoelectronics may make use of the obtained nanocomposite films.\u003c/p\u003e \u003cp\u003eIn an individual work, Zhao [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e] synthesized poly(vinyl alcohol)/silica nano-composites hybrid membranes by co-hydrolyzing and co-condensing tetraethoxysilane (TEOS) and γ-glycidyloxypropyl trimethoxysilane (GPTMS) in an aqueous solution of poly(vinyl alcohol) (PVA). The findings showed that the addition of GPTMS significantly improved the organic phase's compatibility of the inorganic phase, as well as that an appropriate concentration of GPTMS generated nanoscale, uniformly distributed silica particles during the sol-gel process, enhancing the mechanical properties of hybrids.\u003c/p\u003e \u003cp\u003eZhang et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e] by chemically crosslinking in a saturated boric acid solution, a polyvinyl alcohol (PVA) hydrogel including precipitated silica (PSi) was developed. By chemical crosslinking in saturated boric acid solution, a polyvinyl alcohol (PVA) hydrogel comprising precipitated silica (PSi) was developed in a study by Zhang et al. [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]. It was found that PSi may accelerate the crosslinking process by consuming boric acid, and the intermolecular bonding between the PVA and PSi composite was confirmed. A sufficient PSi content may effectively demonstrate the hydrogel's mechanical properties and show that PSi acts as reinforcement on the hydrogel. The water absorption rate and equilibrium swelling rate may both be significantly increased by the addition of PSi, showing the greater capillary capacity for water absorption of PVA hydrogel. The PVA/PSi composite hydrogels' porous properties showed how the addition of PSi allowed the hydrogel to create several sizable pores that operated as pathways for microbiological metabolites. In addition, results from immobilizing activated sludge with PVA hydrogel for wastewater treatment demonstrated that the microorganism bioactivity of PVA immobilized beads could be enhanced above 2.0 wt%.\u003c/p\u003e \u003cp\u003eThe effects of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles on polyvinyl alcohol/carboxymethyl cellulose polymer blend films have been examined by Soliman [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. The findings demonstrated that, as the proportion of SiO\u003csub\u003e2\u003c/sub\u003e increased, the blend film's transparency slightly decreased. Additionally, a redshift in the absorption edge was noted, suggesting that the optical bandgap energy decreased. Their enhanced film absorption and reduced transparency render them cheaper for use in UV-shielding applications. For the PVA/CMC/4 weight percent SiO\u003csub\u003e2\u003c/sub\u003e, the optical bandgap drops from 5.52 eV for pure PVA/CMC to 5.17 eV. The refractive index increases as matrix density rises, and this drop was caused by imperfections in the material. PVA/CMC/SiO\u003csub\u003e2\u003c/sub\u003e, the prepared current matrix, is believed to represent an intriguing possibility for optical applications.\u003c/p\u003e \u003cp\u003eIn a recent study Wu et al. [ 12] synthesized a hybrid material based on a PVA matrix doped with SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles at different contents. They showed the growth of hydrophilicity, on the other hand the contact angle decreases with the increase in the SiO\u003csub\u003e2\u003c/sub\u003e content.\u003c/p\u003e \u003cp\u003eAs showed in several studies, adding SiO\u003csub\u003e2\u003c/sub\u003e to polyvinyl alcohol (PVA) improves the properties of the latter. Sabr et al. [\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e] synthesized a Poly (vinyl alcohol)/silica with various nano-SiO\u003csub\u003e2\u003c/sub\u003e content, to Improving Mechanical and Morphological Characteristics of this hybrid films, discovered that the PVA with 7wt % nano-SiO\u003csub\u003e2\u003c/sub\u003e content exhibited the highest properties.\u003c/p\u003e \u003cp\u003eBandyopadhyay et al [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e] conducted an experiment where they combined Poly (vinyl alcohol) and silica at varying (TEOS) ratios. They observed an improvement in the water resistance and mechanical properties of PVA, and identified the optimal tensile strength at 40% TEOS or 16% of SiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e \u003cp\u003ePingan et al [\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e] created an adhesive composed of 50% silica and 50% PVA, and explored the impact of the H\u003csub\u003e2\u003c/sub\u003eO/TEOS ratio on the material. They discovered that the PVA/silica composite exhibited outstanding mechanical properties and thermal stability while maintaining high transparency, surpassing that of neat PVA. They concluded that the ideal molar ratio of water to TEOS is 1, leading to a lower crystallinity and better dispersion. Hanh et al. [\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e] have developed a composite film made of polyvinyl alcohol (PVA) and glycerol, which includes nanosilica that had been extracted from bottom ash (BA) from solid waste from municipal incinerators. The findings show that the film with 1% silica has a 50% greater tensile strength compared to the film without silica. This represents an important increase in tensile strength. However, due to silica agglomeration within the polymer matrix, increased silica loadings lead to a reduction of mechanical properties. Yaseen et al. [\u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e] have recently reported the synthesis, characterization, and application of a polymer-based ternary nanocomposite (CuO\u0026ndash;SiO\u003csub\u003e2\u003c/sub\u003e/PVA) for the elimination of Nile Blue (NB) and Methylene Blue (MB) contaminants from wastewater, as well as researching its potential biological properties. This is carried out when combined with other inorganic compounds like CuO. It has been suggested that this particular composite might remove more bacteria and contaminants from wastewater. Phadkule et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] investigated the impact of ZnO, SiO\u003csub\u003e2\u003c/sub\u003e, and ZnO-SiO\u003csub\u003e2\u003c/sub\u003e nanoparticle additions on the mechanical, structural, and water absorption properties of Polyvinyl Alcohol (PVA) films. For the PVA-ZnO, PVA-SiO\u003csub\u003e2\u003c/sub\u003e, and PVA-ZnO-SiO\u003csub\u003e2\u003c/sub\u003e films, the addition of nanoparticles improved the tensile strength of the composite films by 14%, 23%, and 66%, respectively, when compared to the pure PVA films. The study presents an easy approach for adjusting the properties of PVA mixed with nanoparticles of metal oxide for applications such as food packaging and medicine.\u003c/p\u003e \u003cp\u003eWith another technique, Nirwan et al. [\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e] investigated the synthesis of PVA/SiO\u003csub\u003e2\u003c/sub\u003e nanofibers by the electrospinning method for supercapacitor separators. They concluded that the silica concentration has an effect on the size of the nanofibers obtained, and increasing the silica concentration leads to a reduction in the diameter of the fibers. The best values obtained are 151% for electrolyte absorption and 60% for electrolyte retention, which shows the potential of PVA/silica nanofibers as an alternative material for supercapacitor separators.\u003c/p\u003e \u003cp\u003ePVA/SiO\u003csub\u003e2\u003c/sub\u003e nanocomposites remain a highly sought-after subject of study as they have offered solutions to a wide variety of current problems facing humanity. According to the sol-gel method, it is possible to fabricate hybrid materials at low temperatures, which is crucial to preserve the characteristics of PVA while promoting a homogeneous dispersion of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles. In addition, this method offers the possibility to precisely modify the characteristics of the final material by changing the synthesis parameters such as pH, reagent concentration, and drying conditions. This work aims to synthesize and characterize a hybrid material based on poly(vinyl alcohol)/silica gel using the sol-gel process. The effect of processing parameters like HCl concentration and drying temperature on gel setting time has been extensively studied; the SiO\u003csub\u003e2\u003c/sub\u003e content was limited only for the spectroscopic analysis (FTIR and UV-VIS). However, the effect of thermal and physical properties was only taken into account for the PVA/SiO2 hybrid composite containing 16% SiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e"},{"header":"EXPERIMENTAL PART","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eMaterials\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003ePoly (vinyl alcohol) degree of polymerization\u0026thinsp;=\u0026thinsp;1800, 98% hydrolyzed with Mw\u0026thinsp;=\u0026thinsp;15000, Tetraethyl orthosilicate (TEOS) (98%, Mw\u0026thinsp;=\u0026thinsp;208.33g/mol, d\u0026thinsp;=\u0026thinsp;0.933g/ml), Ethanol (C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eOH) (96% (v/v) Mw\u0026thinsp;=\u0026thinsp;46.07 g/mol, d\u0026thinsp;=\u0026thinsp;0.789g/ml), and hydrochloric acid (HCl) (38%, M\u0026thinsp;=\u0026thinsp;36.46g/mol, d\u0026thinsp;=\u0026thinsp;1.19g/ml), all of these materials were supplied by Sigma-Aldrich. Deionized water (DI) was used throughout all the experiments. All chemicals and materials were obtained and used as received without any further purification.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003ePreparation of the Films\u003c/h3\u003e\n\u003cp\u003eIn the first step, tetraethoxysilane (TEOS), ethanol, water was mixed and stirred for 15 min at 50\u0026deg;C. Volumes of components are listed in Table.1. and Table.2. A series of tubes tests containing 10ml from solution (TEOS\u0026thinsp;+\u0026thinsp;Ethanol\u0026thinsp;+\u0026thinsp;H\u003csub\u003e2\u003c/sub\u003eO) have been prepared. The mixtures were prepared by the addition of some drops of HCl catalyst at 50\u0026deg;C to the solution with constant stirring during 10 min. Every series of preparation of silica gel mixtures was put in oven and drying at different temperatures: 50, 70, 80, 90, 100, 110\u0026deg;C.The time of gelation was noted.\u003c/p\u003e \u003cp\u003eTwo types of films were prepared: neat PVA film and PVA/SiO\u003csub\u003e2\u003c/sub\u003e film. For the neat PVA film, 5 g of PVA was dissolved in 100 ml of deionized water (5 percent) by magnetic mixing and heating at 80\u0026deg;C for 1 hour until the mixture was homogeneous and viscous. The gel was then placed into a petri dish and allowed to solidify at room temperature for three days. For the PVA/SiO\u003csub\u003e2\u003c/sub\u003e film, different concentrations of tetraethyl orthosilicate (TEOS) ranging from 10 to 90% were dissolved in ethanol, deionized water, and hydrochloric acid at a molar ratio of 1:4:1:0.04 of TEOS/Ethanol/Water/HCl, respectively. The PVA solution was gradually added separately to each solution of TEOS and stirred for 1 hour at 60\u0026deg;C. The resulting mixture was poured into a Petri dish and allowed to solidify at room temperature for 3 days. The scheme of the PVA/TEOS interaction material is shown in Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e [\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e21\u003c/span\u003e].\u003c/p\u003e \u003cp\u003e \u003c/p\u003e\n\u003ch3\u003eCharacterization\u003c/h3\u003e\n\u003cp\u003eSeveral analytical techniques were employed to characterize the samples. The study by the XRD, DSC, TGA and water absorption tests have been only limited for the content of 16% of SiO\u003csub\u003e2\u003c/sub\u003e. In agreement with the work done by (Bandyopadhyay et al, Nakane K et al) [\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e] on the effect of silica gel content on the properties of PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrid materials that the best SiO\u003csub\u003e2\u003c/sub\u003e content is 16% by weight. However, the spectroscopic study of PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrid films by FTIR and UV-VIS spectroscopy has been used for different Sio2 contents (10, 20, 30, 40,50, 60,70, 80 and 90%).\u003c/p\u003e \u003cp\u003eFourier Transform Infrared Spectroscopy (FT-IR) was used to record the infrared spectra, using a Perkin Elmer FTIR Spectrum 1000 spectrophotometer in transmission mode at room temperature. The samples underwent 32 scans, and X-ray Diffraction (XRD) measurements were conducted using a Phillips X'PERT Pro diffractometer with a CuKα radiation source, while UV-VIS Spectrophotometry was carried out using a Perkin Elmer 4B spectrophotometer to record the absorption and transmission spectra of the samples in the range of 200\u0026ndash;800 cm-1. Thermogravimetric analysis (TGA) was carried out in an N\u003csub\u003e2\u003c/sub\u003e atmosphere using a Mettler Toledo Star System, while Differential Scanning Calorimetry (DSC) was performed using a Perkin-Elmer differential scanning calorimeter. The water absorption rate of the samples was determined using the ASTM-D570-81 procedure, and the water uptake was calculated using Eq.\u0026nbsp;\u003cspan refid=\"Equ1\" class=\"InternalRef\"\u003e1\u003c/span\u003e and plotted against time, where W represents the water uptake, m\u003csub\u003e0\u003c/sub\u003e is the initial dry weight of the film, and m\u003csub\u003et\u003c/sub\u003e is the dry weight of the swollen film.\u003cdiv id=\"Equ1\" class=\"Equation\"\u003e\u003cdiv format=\"TEX\" class=\"mathdisplay\" id=\"FileID_Equ1\" name=\"EquationSource\"\u003e\n$$\\:\\mathbf{W}\\left(\\mathbf{\\%}\\right)=\\left[\\frac{{\\varvec{m}}_{\\varvec{t}}-{\\varvec{m}}_{0}}{{\\varvec{m}}_{0}}\\right].100\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:\\:$$\u003c/div\u003e\u003cdiv class=\"EquationNumber\"\u003e1\u003c/div\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"RESULTS AND DISCUSSION","content":"\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n \u003ch2\u003eProcessing Parameters\u003c/h2\u003e\n \u003cp\u003eIn the present study, we have attempts, in a first time so study some parameters who affect the rate of gelation during formation of silica gel like the acid content and the drying temperature. Moreover, by using a purely aqueous medium the use of expensive and very often toxic solvents has been avoided. In a second time, the preparation of PVA/silica hybrid from the optimum conditions of reaction of condensation.\u003c/p\u003e\n \u003cp\u003eThe synthesis of PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrids typically involves the sol-gel process, where tetraethyl orthosilicate (TEOS) is hydrolysed and condensed in the presence of PVA. Hydrochloric acid (HCl) is commonly used as a catalyst in this process to control the rate of hydrolysis and condensation of the silica precursor, which ultimately affects the gelation time or gel setting time of the resulting PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrid\u003c/p\u003e\n \u003cp\u003eThe gelation time, or gel setting time, is a critical parameter in this process, and both the concentration of HCl and the temperature of the solution can influence it.\u003c/p\u003e\n \u003cp\u003eThe time of gelation as function of drying temperature is shown in Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e for different drops of HCl. As can be seen, as the number of drops increase, the time of gelation decrease significantly. This decrease is more important as the number drop of HCL is important. However, at drying temperature 110\u0026deg; C the times gelification of different mixtures become almost equals.\u003c/p\u003e\n \u003cp\u003eAs the number of drops of HCl increases, the acidity of the solution increases, which accelerates the hydrolysis of TEOS, leading to faster formation of silanol groups (Si-OH). These silanol groups subsequently undergo condensation to form Si-O-Si bonds, resulting in the formation of a silica network within the PVA matrix. A higher concentration of HCl generally leads to a shorter gelation time, as the reactions proceed more rapidly in a highly acidic environment.\u003c/p\u003e\n \u003cp\u003eThe time of gelation as a function of the acidity of solution for different drying temperatures is given in Fig. \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e. As can be seen if the number drops of HCl increase, the time of gelation decrease. This decrease is very important at drying temperature 110\u0026deg;C.It means that The PH solution has little effect on the reaction of polycondensation. The addition of HCl in different amounts influences the pH of the sol, which directly affects the kinetics of the hydrolysis and condensation reactions of TEOS. A higher concentration of HCl (i.e., more drops) typically results in a faster gelation process because it accelerates the formation and condensation of silanol (Si-OH) groups. However, an excess of HCl can cause rapid and uneven gelation, leading to potential issues such as phase separation or the formation of non-uniform silica networks.\u003c/p\u003e\n \u003cp\u003eThe combination of HCl concentration and drying temperature must be carefully optimized to achieve desirable gelation and drying outcomes. A higher number of HCl drops might require lower drying temperatures to prevent rapid evaporation and potential defects. Conversely, lower HCl concentrations might allow for higher drying temperatures without compromising the uniformity and stability of the hybrid material.\u003c/p\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eModerate drying temperatures (50 and 100\u0026deg;C) strike a balance between the slow evaporation at low temperatures and the rapid drying at high temperatures. This range allows for a more efficient removal of solvents while still maintaining a controlled drying process. The PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrid tends to exhibit good mechanical properties and a stable structure, with reduced drying time compared to lower temperatures.\u003c/p\u003e\n \u003cp\u003eHigher drying temperatures (\u0026gt;\u0026thinsp;100\u0026deg;C) lead to rapid solvent evaporation and faster densification of the silica network. While this can shorten the overall processing time, it also increases the risk of defects such as cracks, due to uneven shrinkage or thermal stresses. High temperatures can also cause the PVA matrix to undergo changes such as thermal degradation or excessive shrinkage, which can negatively affect the mechanical properties of the hybrid material.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n \u003ch2\u003eStructure and Morphology of the Hybrid Films\u003c/h2\u003e\n \u003cdiv id=\"Sec9\" class=\"Section3\"\u003e\n \u003ch2\u003eFourier Transform Infrared Spectroscopy\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eTo investigate the existence of specific chemical groups in the hybrid materials, Fourier Transform Infrared Spectroscopy (FT-IR) was employed.\u003c/p\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e shows the FTIR spectrum of PVA and the hybrid PVA/SiO\u003csub\u003e2\u003c/sub\u003e mixtures at different percentages of TEOS. From this figure there is the appearance of symmetrical and asymmetrical elongation vibrations of the C-H bond of neat PVA and PVA/SiO\u003csub\u003e2\u003c/sub\u003e mixtures.\u003c/p\u003e\n \u003c/div\u003e\n \u003cp\u003eThe relative intensity of the peaks around 3250 cm-1 was lower for the samples containing the SiO\u003csub\u003e2\u003c/sub\u003e than that of the neat PVA sample; it decreases with increasing SiO\u003csub\u003e2\u003c/sub\u003e content, indicating that some of the hydroxyl groups of PVA involved in the condensation reaction with silanol groups (Si\u0026ndash;OH) in silica sol, forming covalently bonded cross-links between organic groups and silica. However, the peak increases when the silica content is 60% by weight. This indicates that the SiO\u003csub\u003e2\u003c/sub\u003e sol is redundant. Moreover, the strong band at 1086 cm\u003csup\u003e\u0026ndash;1\u003c/sup\u003e is attributed to the C-C groups stretching in the crystalline phase of the PVA matrix. The intensity of this band increases as the degree of crystallinity increases.\u003c/p\u003e\n \u003cp\u003eIt is to be noted that this band of crystallinity became flattered in the sample contain silica, which indicates the diminution of crystallinity and that the silica/PVA network has successfully been formed.\u003c/p\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThis peak at 1086 cm\u003csup\u003e-1\u003c/sup\u003e were wider for the samples containing the SiO\u003csub\u003e2\u003c/sub\u003e. It is also noted that the intensity of this peak group decreases with the increase in the silica content. This can be attributed to the adsorption peak overlap of Si\u0026ndash;O\u0026ndash;C and Si\u0026ndash;O\u0026ndash;Si due to the condensation reaction between Si\u0026ndash;OH groups and C\u0026ndash;OH groups of PVA. i.e. many silanol groups condensed with the hydroxyls on the PVA chain to form a Si\u0026ndash;O\u0026ndash;PVA\u0026ndash;O\u0026ndash;Si bridge. The presence of Si\u0026ndash;O\u0026ndash;C and Si\u0026ndash;O\u0026ndash;Si bonds confirmed the existence of a chemical bond between the organic groups and the silica.\u003c/p\u003e\n \u003c/div\u003e\n \u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003ch3\u003eX-Ray DiffractionAnalysis\u003c/h3\u003e\n\u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e presents the X-ray diffraction (XDR) of the hybrid films.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003eX-ray diffraction (XRD) is a powerful technique for studying the crystalline structure of polymers like polyvinyl alcohol (PVA) and its composites. Typically, the neat PVA exhibits a broad diffraction peak around 2\u0026theta;\u0026thinsp;=\u0026thinsp;19.5\u0026deg;, which corresponds to the (101) plane of its orthorhombic crystalline structure.\u003c/p\u003e\n\u003cp\u003eHowever, if amorphous SiO\u003csub\u003e2\u003c/sub\u003e is incorporated, no distinct crystalline peaks of SiO\u003csub\u003e2\u003c/sub\u003e will be observed, the peak becomes significantly broader and shifts in the sample containing silica. These results indicate that the presence of SiO\u003csub\u003e2\u003c/sub\u003e in hybrid films has an impact on the crystallinity of PVA.\u003c/p\u003e\n\u003cp\u003eWhen SiO\u003csub\u003e2\u003c/sub\u003e (silica) is introduced into the PVA matrix, the XRD pattern of the composite (PVA/SiO2) shows significant changes. The presence of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles, which are typically amorphous, leads to a reduction in the intensity of the PVA diffraction peaks. This reduction is due to the disruption of the regular packing of PVA chains, which lowers the overall crystallinity of the composite. In some cases, the broadening of peaks can also be observed, indicating a reduction in the size of crystalline domains.\u003c/p\u003e\n\u003cp\u003eThe broadening of peaks and the presence of a more pronounced amorphous halo are also observed, which can be attributed to the distribution of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles within the PVA matrix. The interaction between PVA and SiO\u003csub\u003e2\u003c/sub\u003e, likely through hydrogen bonding, hinders the crystallization of PVA, leading to a more amorphous structure in the composite.\u003c/p\u003e\n\u003cp\u003eThese changes in the UV-Vis spectra are crucial for tuning the optical properties of PVA/SiO\u003csub\u003e2\u003c/sub\u003e hybrid films for specific applications, such as in optical coatings, sensors, and packaging materials.\u003c/p\u003e\n\u003cdiv id=\"Sec11\" class=\"Section2\"\u003e\n \u003ch2\u003eThermal Properties\u003c/h2\u003e\n \u003cdiv id=\"Sec12\" class=\"Section3\"\u003e\n \u003ch2\u003eThermogravimetric Analysis\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe thermogravimetric curves of neat PVA and PVA/SiO\u003csub\u003e2\u003c/sub\u003e composites are shown in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e\u003c/p\u003e\n \u003c/div\u003e\n \u003cp\u003eAccording to Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e, the thermal degradation of neat PVA demonstrates three major weight loss regions. The initial region occurs at temperatures ranging from 20\u0026ndash;100\u0026deg;C with a maximum weight loss temperature at Tmax, step1\u0026thinsp;=\u0026thinsp;95\u0026deg;C. This region can be attributed to the evaporation of free and bound water molecules, resulting in a small weight loss of 20%. The second region, which exhibits the maximum decomposition rate, takes place between 224 to 486\u0026deg;C and is estimated to result in a weight loss of 15%. This weight loss is due to the degradation of the (-OH) side group, causing the formation of a polyene at Tmax, step2\u0026thinsp;=\u0026thinsp;270\u0026deg;C. The third region, which occurs in the 410\u0026ndash;450\u0026deg;C range with Tmax, step3\u0026thinsp;=\u0026thinsp;430\u0026deg;C, corresponds to the decomposition of the main chain of PVA polymer (cleavage of C\u0026ndash;C backbone) which is also called carbocation or carbonation. This last step leads to a weight loss of 91 wt.% at 600\u0026deg;C, resulting in a total residue of 9%.\u003c/p\u003e\n \u003cp\u003eAfter introducing silica to the PVA matrix, the thermal stability of the PVA/SiO\u003csub\u003e2\u003c/sub\u003e membranes is enhanced, as shown in Fig. \u003cspan class=\"InternalRef\"\u003e6\u003c/span\u003e. In this case, the PVA/SiO\u003csub\u003e2\u003c/sub\u003e thermogram reveals four weight-loss regions with slow and gradual degradation. This may be attributed to the loss of the crystalline structure, which shifts to a more amorphous state due to hydrogen bonding between PVA chains and silanol ends of the silica. This explanation is supported by the FT-IR and DSC results, as discussed earlier. The first weight loss is estimated at 6%, and this is due to the silanol groups and their self-condensation reaction, resulting in the removal of residual solvent molecules (water and ethanol) at temperatures of 30\u0026ndash;170\u0026deg;C. The remaining weight loss regions occur in the temperature ranges of 170\u0026ndash;390\u0026deg;C, 390\u0026ndash;490\u0026deg;C, and 490\u0026ndash;690\u0026deg;C with maximum weight loss temperatures of 120, 330, 455, and 590\u0026deg;C, respectively. These temperatures indicate the degradation of hydroxyl groups with other organic residues of PVA and silica networks. The final residual weight corresponds to 76.9\u0026ndash;83.6% of the global weight, resulting in a total residue of 20%. Overall, it can be concluded that incorporating a silica network into the PVA matrix enhances the thermal stability of the films. This suggests that there is an improvement in the thermal stability of PVA/SiO\u003csub\u003e2\u003c/sub\u003e as the content of TEOS increases.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec13\" class=\"Section2\"\u003e\n \u003ch2\u003eDifferential Scanning Calorimetry\u003c/h2\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eThe analysis of thermal properties of materials is a crucial aspect, and DSC is a significant technique for this purpose. In this study, the DSC analysis was employed to measure the crystallization and melting temperatures (Tc, Tm) of the samples.\u003c/p\u003e\n \u003cp\u003eDSC curves of neat PVA and PVA/SiO\u003csub\u003e2\u003c/sub\u003e are presented in Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003e (a, b). The curves depict both exothermic and endothermic reactions. PVA shows a sharp endothermic peak at 190\u0026deg;C, indicating the melting point (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ea). Conversely When SiO\u003csub\u003e2\u003c/sub\u003e is incorporated into PVA at a concentration of 16%, the DSC curve of the resulting composite film shows modifications compared to neat PVA. The presence of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles can influence the thermal transitions of PVA. The melting peak in the DSC curve might be altered by the addition of SiO\u003csub\u003e2\u003c/sub\u003e. The peak may become broader or shift slightly due to changes in the crystalline structure of PVA. The degree of crystallinity is often reduced in the presence of SiO\u003csub\u003e2\u003c/sub\u003e, leading to a less distinct melting peak. The PVA/SiO\u003csub\u003e2\u003c/sub\u003e exhibits less sharp melting endothermic peak very weak and broad, observed at around 165\u0026deg;C, indicating a decrease of 25\u0026deg;C compared to neat PVA. In contrast, an exothermic peak corresponding to the crystallization region (Tc) is observed for neat PVA at a temperature of 112\u0026deg;C (Fig. \u003cspan class=\"InternalRef\"\u003e7\u003c/span\u003ec), but it is absent in PVA/SiO\u003csub\u003e2\u003c/sub\u003e. This lack of crystallization is caused by the crosslinking reaction between PVA chains and the silanol ends of silica.\u003c/p\u003e\n \u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec14\" class=\"Section2\"\u003e\n \u003ch2\u003ePhysical Properties\u003c/h2\u003e\u003cspan\u003e\n \u003cp\u003e\u003cstrong\u003e3.2.1 Water absorption.\u003c/strong\u003e\u003c/p\u003e\n \u003c/span\u003e\n \u003cdiv class=\"BlockQuote\"\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e8\u003c/span\u003e, shows the level of water absorption for Neat PVA and PVA/SiO\u003csub\u003e2\u003c/sub\u003e composite films. Silicon dioxide (SiO\u003csub\u003e2\u003c/sub\u003e) is inherently hydrophilic due to the presence of surface hydroxyl groups, which can readily interact with water molecules. However, in its bulk form or as a dense film, neat SiO\u003csub\u003e2\u003c/sub\u003e exhibits low water absorption. This is because the tightly packed structure and strong Si-O-Si bonds limit the diffusion of water into the material. Any water absorbed by neat SiO\u003csub\u003e2\u003c/sub\u003e is usually confined to the surface or to the first few molecular layers, and the overall water absorption remains minimal.\u003c/p\u003e\n \u003c/div\u003e\n \u003cp\u003eWhen SiO\u003csub\u003e2\u003c/sub\u003e was incorporated into PVA to form a hybrid film with 16% SiO\u003csub\u003e2\u003c/sub\u003e, the water absorption behavior of the composite changes. The presence of SiO\u003csub\u003e2\u003c/sub\u003e can reduce the overall water absorption of the PVA matrix by disrupting the continuous network of hydroxyl groups. SiO\u003csub\u003e2\u003c/sub\u003e particles can create a more tortuous path for water molecules, reducing the rate and extent of water uptake. Additionally, the interaction between PVA and SiO\u003csub\u003e2\u003c/sub\u003e, such as through hydrogen bonding, can further limit the availability of free hydroxyl groups in PVA to interact with water.\u003c/p\u003e\n \u003cp\u003eThe hydroxyl groups present in PVA make it highly susceptible to water absorption. However, the addition of silica to the PVA matrix results in a significant decrease in water absorption compared to neat PVA. This decrease can be attributed to the possible hydrogen bonding between silica and PVA, which reduces the volume of water absorbed by the polar hydroxyl groups. These observations suggest that these hybrid films could serve as water perm selective membranes. Moreover, given that PVA is currently employed as a biomaterial, these novel hybrid materials could potentially find use in biomedical applications.\u003c/p\u003e\n\u003c/div\u003e"},{"header":"Conclusions","content":"\u003cp\u003eAs it sums up, in order to achieve the appropriate gelation and drying achievements, the combination of HCl concentration and drying temperature must be carefully adjusted the first time. Low drying temperatures can be required for a greater number of HCl drops in order to prevent rapid evaporation and possible imperfections. On the contrary hand, low HCl concentrations may allow greater drying temperatures without affecting the hybrid material's stability and homogeneity.\u003c/p\u003e \u003cp\u003eIn the second time the PVA-SiO\u003csub\u003e2\u003c/sub\u003e hybrid films synthesized using the sol-gel method has been successfully developed with the variation of processing parameters and SiO\u003csub\u003e2\u003c/sub\u003e content. The produced composite PVA/SiO\u003csub\u003e2\u003c/sub\u003e was evaluated for its structural, thermal, spectroscopic, and physical properties through a number of analysis techniques, including FTIR, DRX, DSC, TGA, and water uptake capacity. Based on the obtained findings, it may be concluded that:\u003c/p\u003e \u003cp\u003eThe FT-IR research verified that hydrogen bonds were formed between PVA and SiO\u003csub\u003e2\u003c/sub\u003e at varying concentrations of SiO\u003csub\u003e2\u003c/sub\u003e, signifying a successful interaction between the two components. A chemical connect among the organic groups and the silica has been demonstrated by the presence of Si\u0026ndash;O\u0026ndash;C and Si\u0026ndash;O\u0026ndash;Si bonds.\u003c/p\u003e \u003cp\u003eThe UV-VIS analysis revealed that the optical transmittance of the composite films improved as the SiO\u003csub\u003e2\u003c/sub\u003e content increase for an identical different SiO\u003csub\u003e2\u003c/sub\u003e concentration.\u003c/p\u003e \u003cp\u003eFurthermore, the XRD examination revealed that the addition of nanoparticles led to the creation of a semi-crystalline morphology for the composite PVA/SiO\u003csub\u003e2\u003c/sub\u003e containing 16% of SiO\u003csub\u003e2\u003c/sub\u003e. The intensity of the PVA diffraction peaks diminishes when SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles, which are usually amorphous, are added. The hybrid films' thermal stability increased, depending to the TGA analysis. It has been found that the inclusion of SiO\u003csub\u003e2\u003c/sub\u003e enhanced the hybrid films' ability to absorb water for the same composite.\u003c/p\u003e \u003cp\u003eThese results imply that the structure and physicochemical characteristics of the hybrid films are significantly affected by the inclusion of SiO\u003csub\u003e2\u003c/sub\u003e nanoparticles to the PVA matrix, thereby rendering the films suitable for a range of uses, such biomedical devices, packaging, and sensors. The mechanical and biological properties of these hybrid films can be researched subsequently.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e \u003ch2\u003eConflicts of interest\u003c/h2\u003e \u003cp\u003eThe authors declare no conflict of interest\u003c/p\u003e \u003c/p\u003e\u003ch2\u003eFunding\u003c/h2\u003e \u003cp\u003eno funding\u003c/p\u003e\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eDerradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka conceived of the presented idea Derradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka carried out the experiment. Derradji Dadache, Farid Rouabah, Abdeslam Bencid and Brahim Barka wrote the main manuscript text . Derradji Dadache and Farid Rouabah prepared figures 1-8 and tables 1-2. All authors discussed the results and contributed to the final manuscript. Authors\u0026rsquo; contributions are equal.\u003c/p\u003e\u003ch2\u003eAcknowledgments\u003c/h2\u003e \u003cp\u003eThe authors would like to thank the Ministry of Higher Education and Scientific Research (MESRS) and the General Directorate of Scientific Research and Technological Development (DGRSDT) \u0026ndash; Algeria\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eTirnakci B, Salt Y (2021) preparation and characterization of pva-sio2 nanocomposite membranes for seawater desalination by pervaporation. 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J Appl Poly Sci. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1002/(SICI)1097-4628(19991003)74:1\u0026lt;133AID-APP16\u0026gt;3.0.CO;2-N\u003c/span\u003e\u003cspan address=\"10.1002/(SICI)1097-4628(19991003)74:1%3C133AID-APP16%3E3.0.CO;2-N\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eDodda JM, Bělsk\u0026yacute; P, Chmelař J, Remiš T, Tom\u0026aacute;š M, Kullov\u0026aacute; L, Kadlec J (2015) Comparative study of PVA/SiO2 and PVA/SiO2/glutaraldehyde (GA) nanocomposite membranes prepared by single-step solution casting method. J Mater Sci. \u003cspan class=\"ExternalRef\"\u003e\u003cspan class=\"RefSource\"\u003ehttps://doi.org/10.1007/s10853-015-9206-7\u003c/span\u003e\u003cspan address=\"10.1007/s10853-015-9206-7\" targettype=\"DOI\" class=\"RefTarget\"\u003e\u003c/span\u003e\u003c/span\u003e\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHere are the figures captions with a brief title next to each one\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"},{"header":"Tables","content":"\u003cp\u003e\u003c/p\u003e\n\u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVolume of used sol systems\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSol type\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVolume of TEOS (ml)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVolume of C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e5\u003c/sub\u003eOH\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVolume of H\u003csub\u003e2\u003c/sub\u003eO (ml)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eDrops of HCl\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePolyvinyl alcohol (PVA)(g)\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSol (1)\u0026thinsp;=\u0026thinsp;GS\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e22.6\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e60\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e10\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eVarie from 10 to 17 drops\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSol (2)\u0026thinsp;=\u0026thinsp;P\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e40\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eCompositions and preparation of the hybrid solutions P: Neat PVA, PS: PVA/SiO\u003csub\u003e2\u003c/sub\u003e.\u003c/div\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSample\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePVA\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e(W %)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTEOS\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e(wt %)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eSilica\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e(W %)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTEOS\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e(wt %) in\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eSolution\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePVA\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003e(wt %) in\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003ethe solution\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003esilica: PVA ratio\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003ein solution (by wt)\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eH\u003csub\u003e2\u003c/sub\u003eO/TEOS (mol) ratio\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eHCL/TEOS (mol ) ratio\u003c/div\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eAppearance\u003c/div\u003e\n \u003cdiv class=\"SimplePara\"\u003eof the films\u003c/div\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eP\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e100\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0:1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e90\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e10\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.125\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.25: 2.25\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.01\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS2\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e80\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e20\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e8\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2.25\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.5: 2\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.02\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS3\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e30\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e12\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3.375\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.75: 1.75\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.03\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS4\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e60\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e40\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e16\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e4.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e3\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1:1.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.04\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e50\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e50\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e20\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e5.625\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.25: 1.25\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.05\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS6\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e40\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e60\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e24\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e6.75\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.5: 1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.06\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS7\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e30\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e70\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e28\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e7.875\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1.75: 0.75\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.07\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS8\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e20\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e80\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e32\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e9\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e2: 0.5\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e1\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e0.08\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003eTransparent\u003c/div\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cdiv class=\"SimplePara\"\u003ePS9\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e10\u003c/div\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cdiv class=\"SimplePara\"\u003e90\u003c/div\u003e\n 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\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Poly (vinyl alcohol), Silicon Dioxide, Sol-Gel Method, Hybrid Films, Spectroscopic characterization","lastPublishedDoi":"10.21203/rs.3.rs-6154062/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6154062/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eIn light of their unique properties and potential applications silicon dioxide (SiO\u003csub\u003e2\u003c/sub\u003e) and polyvinyl alcohol (PVA) nanocomposites synthetized through the method known as sol-gel is gaining interest. For the first time, we investigated studied how processing variables like the number of HCl drops and the drying temperature influenced gel setting time. In the second time, tetraethoxysilane (TEOS) was hydrolysed and then condensed in a poly(vinyl alcohol) (PVA) solution to create organic–inorganic hybrid materials (PVA/SiO\u003csub\u003e2\u003c/sub\u003e). With varying SiO\u003csub\u003e2\u003c/sub\u003e contents, the hybrid's optical properties and structure have been studied using infrared (FTIR) spectroscopy. For the hybrid, which includes 16% of SiO\u003csub\u003e2\u003c/sub\u003e, the thermal characteristics were investigated using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Si–O–C and Si–O–Si bond formation in the system was demonstrated using FTIR spectroscopy. TGA and DSC analysis showed that the hybrid films had better thermal stability and a lower melting temperature when compared to neat PVA films. At 190°C, PVA shows an intense endothermic peak, which indicates the melting point. Compared to neat PVA, the PVA/SiO\u003csub\u003e2\u003c/sub\u003e shows a less severe melting endothermic peak which is very weak and broad, discovered around 165°C. This suggests a decrease of 25°C. The hybrid film was also rendered more resistant to water absorption.\u003c/p\u003e","manuscriptTitle":"Formation of PVA-SiO 2 hybrid films by Sol-Gel method: Effect of processing parameters and SiO 2 content on the structure and physico-chemical properties","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-05-15 05:05:33","doi":"10.21203/rs.3.rs-6154062/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"6e81c137-d290-4813-9b34-a3e25769da73","owner":[],"postedDate":"May 15th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-05-30T02:23:42+00:00","versionOfRecord":[],"versionCreatedAt":"2025-05-15 05:05:33","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6154062","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6154062","identity":"rs-6154062","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}