Effect of crystallization time on the properties of PPVA-AlPO 4 nanocomposite synthesis by hydrothermal method at various pH

Effect of crystallization time on the properties of PPVA-AlPO 4 nanocomposite synthesis by hydrothermal method at various pH | 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 Effect of crystallization time on the properties of PPVA-AlPO 4 nanocomposite synthesis by hydrothermal method at various pH Asmalina Mohamed Saat, Nor Aliya Hamizi, Mohd Rafie Johan This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-6900538/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 The hydrothermal method is now widely used in the synthesis of nanomaterials because it is simple, easy and inexpensive to produce. The transformation of nanomaterials into a crystalline structure can be easily modified at different temperatures, pressures and heating modes (conduction, convection or microwaves). This study investigates the effects of pH and crystallization time on the evolution of the microstructure of phosphorylated poly(vinyl alcohol)-aluminum phosphate (PPVA-AlPO4) nanocomposite. The thermal stability, structure and surface morphology were recorded using TGA, FTIR, XRD and FESEM analyses. The microstructure evolves into spherical nanoparticles at low pH and nanowires at highly alkaline conditions. The particle size of the observed nanocomposite decreased with increasing crystallization time. At a crystallization time of two hours, the structure was found to have no OH peak in the water region and the intensity of the C-O-P and O-P-O-Al peaks increased. As a conclusion to produce high crystallinity and uniform distribution of PPVA-AlPO4 nanocomposite nanoparticles, a reaction at a pH of 10 and a crystallization time of 2 hours is suggested. Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Introduction Polyvinyl alcohol (PVA) phosphate nanocomposites are advanced materials formed by integrating phosphate-based nanoparticles into a PVA matrix, leveraging the polymer’s biocompatibility, film-forming ability, and chemical versatility [ 1 ]. These nanocomposites exhibit tailored physicochemical properties through controlled synthesis parameters and nanoparticle modifications, enabling diverse applications in corrosion coating [ 2 ], biomedicine[ 3 , 4 ], energy [ 5 ], and sustainable packaging [ 3 ]. The synthesis of PVA phosphate nanocomposite is challenging to ensure the controlled crystal structure and shape obtained. Systematic synthesis methodologies are needed to solve problems related to interfacial interaction, structural complexity, uniform dispersion, and multifunctionalities [ 6 , 7 ]. Various techniques were employed to synthesize inorganic materials by soft chemical methods [ 8 ], including precipitation, hydrothermal methods [ 9 ], sol–gel, high temperature methods [ 10 , 11 ], and solid-state synthesis. The hydrothermal method is a powerful technique for the synthesis of nanoparticles of a wide variety of materials, including metals, metal oxides, semiconductors, and ceramics. The method is a versatile technique for synthesizing nanoparticles and nanocomposites through controlled high-temperature and high-pressure aqueous reactions. This approach enables precise control over crystal structure, morphology, and composition, making it widely used in materials science and nanotechnology. The hydrothermal method is a wet-chemical technique that involves the crystallization of substances from high-temperature aqueous solutions at high vapor pressures. The process is carried out in a sealed container called an autoclave, which allows the reaction to be performed at a low temperature of less than 100°C and a pressure of less than 1 atm within the sealed autoclave. The autoclave is made from steel vessels and combined with Teflon lining for anti-corrosion protection and sustained extreme conditions during the synthesis process [ 7 ]. The controlled crystallization is usually conducted at lower temperatures between 100 to 500°C, where dissolution occurs at the hot end and crystallization at the cold end [ 8 ]. The reaction temperature, pressure, and reaction time are all important parameters that can affect the size, morphology, and crystallinity of the synthesized nanoparticles. The specific conditions used will vary depending on the type of nanoparticles being synthesized. It is also a relatively simple, inexpensive and environmentally friendly method because the process does not require the use of volatile organic compounds or other toxic solvents. Thus, making it suitable for use in both research and industrial settings. The influence of pH on the synthesis and characterization of PPVA-AlPO4 nanocomposite by the hydrothermal method previously showed varying morphology from nanoparticles to nanorods to nanowires, however, none yet discussed the effect of crystallization time or reaction time[ 1 ]. Therefore, in the present study, we investigated the effects of varying crystallization time on the synthesis of PPVA-AlPO4 nanocomposite by using the hydrothermal method towards the structural, thermal, and morphological characteristics of the PPVA-AlPO4 composite. Table 1 shows the summary of the hydrothermal method in the synthesis of nanoparticles. Table 1 Summary of Hydrothermal Synthesis of Nanoparticles Feature Hydrothermal Synthesis Solvent Aqueous solutions (water) Heating Method Conventional heating (ovens, hot plates) Heating Efficiency Relatively slow and uneven heating Reaction Time Longer reaction times (hours to days)[ 7 ] Temperature Control Good control, but gradients may exist Particle Size/Morphology Control Good control through parameter adjustment Energy Consumption Higher energy consumption Environmental Impact Relatively environmentally friendly (water-based) Examples of Nanomaterials Metal oxides (TiO2, ZnO) [ 9 ], metal sulfides, some metals Advantages * Relatively simple setup [ 10 ] * Produces thermally unstable phases [ 8 ] * Relatively low temperature processing. [ 9 ] * Precise composition control [ 8 ] * Enables large, high-quality crystals Disadvantages * Long reaction times. * Limited to water-soluble precursors. * High equipment costs (specialized autoclaves) [ 8 ] * Corrosion risks require protective linings Methodology Partially phosphorylated polyvinyl alcohol-aluminum phosphate (PPVA-AlPO 4 ) is a composite material made by combining two components: partially phosphorylated polyvinyl alcohol (PPVA) and aluminum phosphate (AlPO 4 ). The PPVA and AlPO 4 are combined through a process like continuous stirring and condensation. Here's a breakdown of some key points about PPVA-AlPO 4 . The PPVA-AlPO4 is made through methods like solution casting or continuous stirring at moderate temperatures (around 80°C). The process starts with modification of PVA with phosphoric acid and in situ reaction of aluminum phosphate in the mixture. The mixture was later treated by the hydrothermal method after controlling the pH at 10. The mixture was put in an autoclave and heated at a controlled temperature of 120 ˚C at various reaction times (2, 12 and 24 hours). The samples were then characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform Infra-red (FTIR) and field emission scanning electron microscope (FESEM) and compared with as-prepared sample. Table 1 Formulation for synthesis of PPVA-AlPO 4 nanocomposite at various pH 10 and crystallization time. Samples Crystallization time (hour) Ratio of Al:P Heat treatment Reaction pH pH 10-A As prepared 1.3:3 No heat treatment 10 pH 10-B 120˚ C, 2hours 1.3:3 120 ˚C, 2 hours 10 pH 10-C 120˚ C, 12hours 1.3:3 120 ˚C, 12 hours 10 pH 10-D 120˚ C, 24hours 1.3:3 120 ˚C, 24 hours 10 Results and Discussion Thermogravimetric (TGA) analysis Figure 1 shows the TGA traces of PPVA-AlPO 4 samples at pH 10 for as-prepared samples and heat-treated samples at 120 ˚C for various crystallization times. Samples prepared at crystallization times of 2 and 24 hours produce maximum weight residues of 62 and 63 wt%, respectively. Meanwhile, the weight residues for as-prepared sample and the sample prepared at a crystallization time of 12 hours are 59 and 58 wt%, respectively. A longer crystallization time produces higher weight residue due to more interaction between Al-O-P after the elimination of H and OH anions that affected the Al-O-P bond. The degradation stage was similar for all crystallization time and as prepared samples. Pramanik, (2009) reported that the heat-treated PPVA at 120 ˚C for 2 hours provides the maximum bonding between PVA and the phosphate group [ 11 ]. This result is in good agreement with Pramanik, (2009) as the PPVA-AlPO 4 nanocomposite synthesized using a combination of refluxing, stirring, chemical precipitation and hydrothermal at 120 ˚C for 2 hours also produced maximum weight residue due to the maximum bonding between PPVA and AlPO 4 [ 11 ]. X-Ray Diffraction (XRD) Analysis Figure 2 shows the XRD patterns for PPVA-AlPO 4 nanocomposite samples at pH 10 for as-prepared and heat-treated samples at 120 ˚C for various crystallization times. The XRD spectra at a range of 5 to 12˚ (110), 23.84˚ (121) and 33.92˚ (52 − 1) match the XRD PDF database 000-037-0189 of potassium aluminum phosphate (K 2 Al 2 P 8 O 28 ) with a monoclinic crystal system. The XRD peak at an angle of 29.69˚ (220) matches the XRD PDF database 000-036-1459 of potassium aluminum phosphate (K Al P 2 O 7 ) with a monoclinic crystal system. Meanwhile, 32.60˚ (060) and 33.34˚ (142) match the XRD PDF database of 98-007-4175 aluminum phosphate hydrate (1/1/2.5) with a hexagonal crystal system. The XRD peaks at 24.0996 (0 2 4), 41.4163 (2 1 28) and 42.0886 (1 2 29) also have the taranakite system that matches the PDF reference code 01-089-0895 known as potassium aluminum deuterium phosphate deuterate (K 3 Al 5 (DPO 4 ) 6 (PO 4 ) 2 (D 2 O) 18 ) and have a rhombohedral crystal system. The (110) peak shows an increase in intensity as crystallization time increases with maximum intensity observed the in sample heat-treated at 24 hours crystallization time. The peak also becomes broadened as crystallization time increases due to the interaction of PPVA and aluminum. The XRD peak at an angle of 19.27 originating from PVA and PPVA samples shows an increase in intensity from as-prepared to 12 hours crystallization time samples due to the interaction of PPVA with heat. The XRD peaks of (121), (220), (060), (5 2 − 1), (2 1 28) and (1 2 29) show an increase in intensity as crystallization time increases to 12 hours. Then the intensity decreases as the crystallization time reaches 24 hours. However, at peaks of 33.34˚ and 37.5˚, a decrease in peak intensity as the crystallization time increases due to the Al(OH) peak that still occurred at lower temperatures and slowly vanishes at higher temperatures or longer crystallization times. Figure 3 shows the XRD crystallite size distribution for various 2θ and crystallization times. The smallest crystal size observed in samples with a crystallization time of 24 hours at a peak of 32.60˚ (060) was 26.53 nm. In general, the crystallite size decreased as the crystallization time increased. Table 2 summarizes the XRD data analysis of types of aluminium phosphate, the crystal system, the 2θ position and crystal size at various crystallization times. Table 2 Summary of XRD data analysis of types of aluminum phosphate, crystal system, 2θ value, crystal size, D for PPVA-AlPO 4 nanocomposite at pH 10 with different crystallization time. XRD Pdf database Name Crystal system Position 2θ (˚) XRD crystal size, D (nm) pH10-A As prepared pH10-B 120˚ C, 2 hours pH10-C 120˚ C, 12 hours pH10-D 120˚ C, 24 hours 000-037-0189 Potassium Aluminum Phosphate (K2 Al2 P8 O28) Monoclinic 5–12 ˚ (110) - - - - 23.84 ˚ (121) 45.32 45.32 63.46 52.03 33.92 ˚ (52 − 1) 81.17 - 108.13 - 000-036-1459 Potassium Aluminum Phosphate (K Al P2 O7) Monoclinic 29.69 ˚ (220) 40.14 45.88 64.24 - 98-007-4175 Aluminum Phosphate Hydrate (1/1/2.5) Hexagonal 32.60 ˚ (060) 53.91 40.43 35.94 26.53 33.34 ˚ (142) 64.83 107.98 64.82 44.29 01-089-0895 Potassium Aluminum Deuterium Phosphate Deuterate (K3Al5(DPO4)6(PO4)2(D2O)18) Rhombohedral 24.0996 ˚ (0 2 4) 63.5 79.39 79.39 52.07 41.4163 ˚ (2 1 28) 55.32 47.41 47.4 27.22 Fourier Transform Infra-Red (FTIR) spectroscopy analysis Figure 4 shows the FTIR spectra for PPVA-AlPO 4 nanocomposites at pH 10 for as-prepared and heat-treated samples at 120 ˚C for various crystallization times. The Al-OH band was observed in as-prepared and 12 hours samples due to the OH group. Samples prepared at lower crystallization time (2 hours) and at 12 hours show no Al-OH band. All samples produce an OH peak (3371–3402 cm − 1 ), C-OH water bending (1615–1650), PO-AlPO 4 (1369–1376 cm − 1 ), C-O-P-AlPO 4 (1030–1058 cm − 1 ) and O-P-O-AlPO 4 (541–593 cm − 1 ) regardless of crystallization time. Meanwhile, a few samples (2 hours crystallization time) show the Al-O-P band in the region of 2349 − 2090 cm − 1 . These samples show no water bending at the range of 1730–1740 cm − 1 . Figures 5 (a) and (b) show the effect of crystallization time for four FTIR bands, PO-AlPO 4 , C-O-P-AlPO 4 , OH and O-P-O. Both PO-AlPO 4 and C-O-P-AlPO 4 bands are shifted to higher wavenumbers as the crystallization time increases. The OH band in Fig. 5 (b) also had a similar trend. However, the O-P-O band is shifted to a higher wavenumber until 12 hours of crystallization time. Beyond that, the wavenumber is shifted back to a lower wavenumber. The shifted peak towards higher wavenumber shows that the OH band is influencing the PO-AlPO 4 and C-O-P-AlPO 4 bands. The amount of water is increased for samples with 2 to 12 hours of crystallization time. However, at a higher crystallization time of 24 hours, dehydration of samples has occurred that produces a peak that shifted back to the lower wavenumber. From the observation, sample prepared with 2 hours crystallization time produce more Al-O-P bonds, less Al-OH and no water bending H-O-H at a range of 1730–1740 cm − 1 . Field Emission Scanning Electron Microscopy (FESEM) Analysis Figure 6 shows the FESEM images for PPVA-AlPO4 nanocomposite samples at pH 10 for as-prepared and heat-treated at 120 ˚C for various crystallization times. All samples contain spherical and layer structures. Spherical particles are observed in the prepared samples as shown in Fig. 6 (a). It is observed layer structure formation on the sample surface. The layer structure ratio increases and exists between the spherical particles as the crystallization time increases to 12 hours as shown in Fig. 6 (c). As the crystallization time increases, the ratio of component particulate and layer varies. The spherical particles are dominant at shorter crystallization times. However, at the longer crystallization time, the particles are agglomerated to form a more layered structure. A higher region of layer structure is observed at 24 hours crystallization time compared to other samples. The spherical particle reduces as the crystal nucleation and growth accelerate at longer crystallization times. Yang et al., 2014 observed similar results that the crystallization time is only influence the aspect ratio and uniformity of particles [ 12 ]. Figure 7 shows the FESEM micrographs (200x magnification) of PPVA-AlPO 4 nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for various crystallization time: (b) 2, (c) 12 and (d) 24 hours with measured sizes. Figure 7(a) shows the nanoparticles are homogeneously distributed with a spherical shape and a size less than 50 nm. The presence of immiscible of taranakite layer is also observed. At higher magnification (200x), the image shows agglomeration of AlPO 4 particles into various sizes (16–20 nm). This size is in different value from the calculated crystallite size through XRD. However, they are still in a nano region. There is no polymer phase observed in the system. The size of AlPO 4 nanoparticles is smaller and more homogeneously distributed as compared to AlPO 4 nanoparticles obtained by Palacios et al., (2013), which were synthesis at pH 6 for 480 min [ 13 ]. The homogeneous particle distribution with smaller size is due to the effectiveness of PPVA as the encapsulating material for better interfacial bonding through its pendant groups with aluminum phosphate. This is in good agreement with Pramanik et al. (2009) that PPVA provides an effective method for better dispersion of nanoparticles in the polymer matrix with a strong particle polymer interfacial bonding through its phosphate groups [ 11 ]. The nuclei grow uniformly by diffusion of solutes from the solution to its surface until they reach the final shape. However, the uniform particles are also obtained after the occurrence of multiple nucleation. The observed nanoparticles are a result of microstructure development, where agglomeration of small particles accumulated and formed bigger particles. FESEM images show that AlPO 4 nanoparticles are developed from the agglomeration of very small particles. PPVA-AlPO 4 nanocomposite is also observed to contain the immiscible layer and nanoparticle which is in good agreement with the XRD pattern (Fig. 2 ). From Ostwald ripening and Wuff construction theory, the particle size in the nanometer range and exhibiting irregular geometry will experience more stress and strain on the surface [ 14 ]. However, for larger sizes of spherical particles, the stress and strain are less [ 14 ]. Samples prepared at 2 hours crystallization (Fig. 7(b)) time show layers mixed with spherical and nanotube structures are observed at pH 10. The average particle size is less than 15 nm. Figures 7(c) show the FESEM micrographs of PPVA-AlPO 4 nanocomposites prepared at 12 hours crystallization time. A sample prepared at pH 10 shows a bulky structure of heterogeneous shape of AlPO 4 with a distribution of spherical nanoparticles on the surface. The average particle size for samples prepared at pH 10 is less than 10 nm. Figures 7(d) the FESEM micrographs of PPVA-AlPO 4 nanocomposite samples prepared at 24 hours crystallization time. Spherical nanoparticles are distributed on the surface of layer structures as observed at pH 10. Also being observed is a small ratio of nanotubes co-existing with spherical and layer structures. A sample prepared at a shorter crystallization time of 2 hours shows homogeneous nano spherical particles at a lower pH. However, it produces a mixture of spherical and entangled aligned nanoparticles forming a shape similar to a nanotube at higher pH. Yet, there is no study to confirm the occurrence of holes in similar nanotube structures. The average particle size for samples prepared at pH 10 is under 13 nm.Kawamura et al., (2007), reported that by controlling the pH and temperature, the number of H + and OH − ions thus affected the morphologies of PPVA-AlPO 4 nanocomposites that can be controlled [ 15 ]. Our observation suggests that at shorter crystallization times, morphologies are affected by pH but not the size of particles. However, at longer crystallization times, pH variation will vary the geometrical structure and the size of spherical particles.Palacios et al., (2013) also reported a similar observation, nevertheless they observed an increase in particle size with an increase in crystallization time [ 13 ]. Additionally, they also observed an agglomeration and heterogeneous morphology phase distribution as crystallization time increases.Yang & Kau, (2005) reported that the dehydration and condensation of the EO fraction used to synthesize AlPO 4 nanoparticles produced a chain shape [ 16 ]. Thus, heat treatment does affect the morphologies of AlPO 4 . Other than that, they elaborated on the phosphate ion condensation/polymerization leading to the formation of condensed phosphates, which can be linear, cyclic and/or cross-linked/branched phosphates formed upon drying at higher temperatures. This observation explained the occurrence of nanotube structure that appeared at pH 10 after the autoclaving process.Burrell et al., (1999) reported that various morphologies occurred after autoclaving due to the occurrence of double hydroxide bridges during the autoclaving process [ 17 ]. This double hydroxide bridge varies by the number of H + and OH − ions present that may also contribute to the formation of nanotube structure [ 17 ]. Conclusion The effect of crystallization time on PPVA-AlPO 4 nanocomposite analyzed from thermal analysis shows maximum weight residue at crystallization times of 2 and 24 hours. The XRD spherical particle size calculation shows that the average particle size decreases as the crystallization time decreases. The broad peak becoming more intense shows an increase in crystallinity of PPVA-AlPO 4 nanocomposite. The FTIR analysis shows intense C-O-P-Al and O-P-O-Al peaks at both 2 and 12 hours of crystallization time due to the occurrence of more Al-PO 4 compared to Al-OH. At crystallization time, 2 hours shows no Al-OH peak at the water region, which suggests the best condition to produce PPVA-AlPO 4 nanocomposite. However, the FESEM micrograph analysis observed varying interesting morphology of PPVA-AlPO 4 nanocomposite as crystallization time increase. Sample preparation at the crystallization times of 2 and 24 hours shows growth of nanotubes at high alkaline regions. As a conclusion, to produce a better interaction of PPVA and aluminum phosphate with unique morphology, the best crystallization time would be 2 hours. Declarations Acknowledgement The authors acknowledge the Malaysian Institute of Marine Engineering Technology and the Universiti Malaya. Funding Declaration The authors hereby declared that there is no funding related to the work reported in this manuscript. Competing Interests Authors are required to disclose financial or non-financial interests that are directly or indirectly related to the work submitted for publication. Please refer to “Competing Interests and Funding” below for more information on how to complete this section. Author Contributions Statement Asmalina Mohamed Saat performed the measurements, planning and supervised the work, processed the experimental data, performed the analysis, drafted the manuscript and designed the figures. Nor Aliya Hamizi and Mohd Rafie Johan aided in interpreting the results and worked on the manuscript. All authors discussed the results and commented on the manuscript. References A. M. 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Okuwaki, “Morphology of aluminum phosphate by the Al-EDTA mediated particle formation in aqueous solutions at high temperatures,” Mater Res Bull, vol. 42, no. 2, pp. 256–264, Feb. 2007, doi: 10.1016/j.materresbull.2006.06.005. C.-S. Yang and K.-Y. Kau, “Synthesis of Morphology Processable a-AlPO 4 Nanoparticles , Nanowires and Multi-strand Nano-ropes,” Journal of the Chinese Chemical Society , vol. 52, pp. 477–487, 2005. L. S. Burrell, E. B. Lindblad, J. L. White, and S. L. Hem, “Stability of aluminium-containing adjuvants to autoclaving,” Vaccine , vol. 17, no. 20–21, pp. 2599–2603, Jun. 1999, doi: 10.1016/S0264-410X(99)00051-1. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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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-6900538","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":483436322,"identity":"6c56fdd7-d072-4b41-8301-c505e7252a08","order_by":0,"name":"Asmalina Mohamed Saat","email":"","orcid":"","institution":"Universiti Kuala Lumpur","correspondingAuthor":false,"prefix":"","firstName":"Asmalina","middleName":"Mohamed","lastName":"Saat","suffix":""},{"id":483436324,"identity":"c3829f1e-3bc0-4ec2-8f70-90d64d1ae717","order_by":1,"name":"Nor Aliya Hamizi","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9ElEQVRIiWNgGAWjYDACdsYGBiBiYGNgbHwAFjlASAszQkuzAZFagBikBQjYJIjSwt/M3Cbxc4ddNB//4bZq3hwGOb4bCaybefBokTjM2CbZeyY5t43hYNtt3m0MxpI3Ethu49PCANQiwdvGnNvG2AjWkriBkBZ5kC1/2+pz25gZ24qBWuoJajEAapHmbTuc28bG2MYM1JJgQEiL4WHGZmvZtuO5bTyMzZJzt0kYzjzzsO3mHDxa5I63P7z5tq06d37/8Ycf3m6zkec7nnzsxht83mdgYJFA4oDYjA1MeEMMGJkfMIQYf+DXMgpGwSgYBSMLAACnUU8WL1TeqAAAAABJRU5ErkJggg==","orcid":"","institution":"Universiti Malaya","correspondingAuthor":true,"prefix":"","firstName":"Nor","middleName":"Aliya","lastName":"Hamizi","suffix":""},{"id":483436326,"identity":"0dbb280d-1950-4d05-a6b7-22d499fc0902","order_by":2,"name":"Mohd Rafie Johan","email":"","orcid":"","institution":"Universiti Malaya","correspondingAuthor":false,"prefix":"","firstName":"Mohd","middleName":"Rafie","lastName":"Johan","suffix":""}],"badges":[],"createdAt":"2025-06-16 01:08:09","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-6900538/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-6900538/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":86481149,"identity":"27486c17-d082-4228-a0b3-5ba52d2db9ba","added_by":"auto","created_at":"2025-07-11 07:48:33","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":29767,"visible":true,"origin":"","legend":"\u003cp\u003eTGA traces for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for as-prepared and heat-treated samples at 120 ˚C for 2, 12 and 24 h.\u003c/p\u003e","description":"","filename":"1.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/2703e6425132217d038493fa.png"},{"id":86483169,"identity":"6a77beed-f448-4c40-b36f-a707420553c4","added_by":"auto","created_at":"2025-07-11 07:56:33","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":97305,"visible":true,"origin":"","legend":"\u003cp\u003eXRD patterns for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for (b) 2, (c) 12 and (d) 24 hours\u003c/p\u003e","description":"","filename":"2.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/d406b76622e53e1cf51caab6.png"},{"id":86484010,"identity":"e537145a-c92f-4219-9941-9a99386c4fd2","added_by":"auto","created_at":"2025-07-11 08:04:33","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":17661,"visible":true,"origin":"","legend":"\u003cp\u003eXRD crystal size D (nm) distribution for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared (pH10-A) and heat-treated samples at 120 ˚C for (b) 2hr (pH10-B); (c) 12h (pH10-C) and (d) 24h (pH10-D)\u003c/p\u003e","description":"","filename":"3.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/3ea8a66c8573ed0c55571616.png"},{"id":86483170,"identity":"de80a709-6ccb-4fff-b7a8-44c3524183b4","added_by":"auto","created_at":"2025-07-11 07:56:33","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":53685,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR spectra for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for (b) 2hr; (c) 12h and (d) 24h\u003c/p\u003e","description":"","filename":"4.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/469b0379d9d1439673d70cc7.png"},{"id":86481156,"identity":"fffdc9c6-92bb-4a2e-9668-88a89d467e1d","added_by":"auto","created_at":"2025-07-11 07:48:33","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":44047,"visible":true,"origin":"","legend":"\u003cp\u003eFTIR band of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for as-prepared and at a various crystallization times in the range (a) PO-AlPO\u003csub\u003e4\u003c/sub\u003e (1371-1374 cm\u003csup\u003e-1\u003c/sup\u003e) and C-O-P-AlPO\u003csub\u003e4\u003c/sub\u003e (1027-1047 cm\u003csup\u003e-1\u003c/sup\u003e) and (b) OH (3371-3385 cm\u003csup\u003e-1\u003c/sup\u003e) and O-P-O-AlPO\u003csub\u003e4\u003c/sub\u003e (533-553 cm\u003csup\u003e-1\u003c/sup\u003e).\u003c/p\u003e","description":"","filename":"5.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/4cba0ce03bc7d3e2a9ddd083.png"},{"id":86483175,"identity":"b1b5ee0d-fc9b-4764-bb39-9e52360b1c28","added_by":"auto","created_at":"2025-07-11 07:56:33","extension":"png","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":476209,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM micrographs (100x magnification) of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for various crystallization times (b) 2, (c) 12 and (d) 24 hours.\u003c/p\u003e","description":"","filename":"6.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/995496854c17237642e969aa.png"},{"id":86483174,"identity":"792ef2c5-40ef-43d3-808a-dbc74ce5819d","added_by":"auto","created_at":"2025-07-11 07:56:33","extension":"png","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":527881,"visible":true,"origin":"","legend":"\u003cp\u003eFESEM micrographs (200x magnification) of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for various crystallization times (b) 2, (c) 12 and (d) 24 hrs with measured sizes.\u003c/p\u003e","description":"","filename":"7.png","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/4af1b1c962e40a3dff3a09dc.png"},{"id":86791710,"identity":"06de6836-6294-4931-801b-146473e2c4c9","added_by":"auto","created_at":"2025-07-15 15:02:09","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1932494,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-6900538/v1/c999df18-5c99-429a-8e80-96ac8c736d07.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Effect of crystallization time on the properties of PPVA-AlPO 4 nanocomposite synthesis by hydrothermal method at various pH","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePolyvinyl alcohol (PVA) phosphate nanocomposites are advanced materials formed by integrating phosphate-based nanoparticles into a PVA matrix, leveraging the polymer\u0026rsquo;s biocompatibility, film-forming ability, and chemical versatility [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. These nanocomposites exhibit tailored physicochemical properties through controlled synthesis parameters and nanoparticle modifications, enabling diverse applications in corrosion coating [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e], biomedicine[\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e], energy [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], and sustainable packaging [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e]. The synthesis of PVA phosphate nanocomposite is challenging to ensure the controlled crystal structure and shape obtained. Systematic synthesis methodologies are needed to solve problems related to interfacial interaction, structural complexity, uniform dispersion, and multifunctionalities [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. Various techniques were employed to synthesize inorganic materials by soft chemical methods [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e], including precipitation, hydrothermal methods [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], sol\u0026ndash;gel, high temperature methods [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e, \u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e], and solid-state synthesis. The hydrothermal method is a powerful technique for the synthesis of nanoparticles of a wide variety of materials, including metals, metal oxides, semiconductors, and ceramics. The method is a versatile technique for synthesizing nanoparticles and nanocomposites through controlled high-temperature and high-pressure aqueous reactions. This approach enables precise control over crystal structure, morphology, and composition, making it widely used in materials science and nanotechnology. The hydrothermal method is a wet-chemical technique that involves the crystallization of substances from high-temperature aqueous solutions at high vapor pressures. The process is carried out in a sealed container called an autoclave, which allows the reaction to be performed at a low temperature of less than 100\u0026deg;C and a pressure of less than 1 atm within the sealed autoclave. The autoclave is made from steel vessels and combined with Teflon lining for anti-corrosion protection and sustained extreme conditions during the synthesis process [\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]. The controlled crystallization is usually conducted at lower temperatures between 100 to 500\u0026deg;C, where dissolution occurs at the hot end and crystallization at the cold end [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. The reaction temperature, pressure, and reaction time are all important parameters that can affect the size, morphology, and crystallinity of the synthesized nanoparticles. The specific conditions used will vary depending on the type of nanoparticles being synthesized. It is also a relatively simple, inexpensive and environmentally friendly method because the process does not require the use of volatile organic compounds or other toxic solvents. Thus, making it suitable for use in both research and industrial settings. The influence of pH on the synthesis and characterization of PPVA-AlPO4 nanocomposite by the hydrothermal method previously showed varying morphology from nanoparticles to nanorods to nanowires, however, none yet discussed the effect of crystallization time or reaction time[\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e]. Therefore, in the present study, we investigated the effects of varying crystallization time on the synthesis of PPVA-AlPO4 nanocomposite by using the hydrothermal method towards the structural, thermal, and morphological characteristics of the PPVA-AlPO4 composite. Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e1\u003c/span\u003e shows the summary of the hydrothermal method in the synthesis of nanoparticles.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eSummary of Hydrothermal Synthesis of Nanoparticles\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"2\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eFeature\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHydrothermal Synthesis\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eSolvent\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAqueous solutions (water)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeating Method\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eConventional heating (ovens, hot plates)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eHeating Efficiency\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRelatively slow and uneven heating\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eReaction Time\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eLonger reaction times (hours to days)[\u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e]\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eTemperature Control\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGood control, but gradients may exist\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eParticle Size/Morphology Control\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eGood control through parameter adjustment\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEnergy Consumption\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eHigher energy consumption\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eEnvironmental Impact\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eRelatively environmentally friendly (water-based)\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eExamples of Nanomaterials\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eMetal oxides (TiO2, ZnO) [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], metal sulfides, some metals\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eAdvantages\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e* Relatively simple setup [\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e]\u003c/p\u003e\u003cp\u003e* Produces thermally unstable phases [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\u003cp\u003e* Relatively low temperature processing. [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]\u003c/p\u003e\u003cp\u003e* Precise composition control [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\u003cp\u003e* Enables large, high-quality crystals\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003e\u003cb\u003eDisadvantages\u003c/b\u003e\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e* Long reaction times.\u003c/p\u003e\u003cp\u003e* Limited to water-soluble precursors.\u003c/p\u003e\u003cp\u003e* High equipment costs (specialized autoclaves) [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]\u003c/p\u003e\u003cp\u003e* Corrosion risks require protective linings\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Methodology","content":"\u003cp\u003ePartially phosphorylated polyvinyl alcohol-aluminum phosphate (PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e) is a composite material made by combining two components: partially phosphorylated polyvinyl alcohol (PPVA) and aluminum phosphate (AlPO\u003csub\u003e4\u003c/sub\u003e). The PPVA and AlPO\u003csub\u003e4\u003c/sub\u003e are combined through a process like continuous stirring and condensation. Here's a breakdown of some key points about PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e. The PPVA-AlPO4 is made through methods like solution casting or continuous stirring at moderate temperatures (around 80\u0026deg;C). The process starts with modification of PVA with phosphoric acid and in situ reaction of aluminum phosphate in the mixture. The mixture was later treated by the hydrothermal method after controlling the pH at 10. The mixture was put in an autoclave and heated at a controlled temperature of 120 ˚C at various reaction times (2, 12 and 24 hours). The samples were then characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), Fourier transform Infra-red (FTIR) and field emission scanning electron microscope (FESEM) and compared with as-prepared sample.\u003c/p\u003e\u003cp\u003e\u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e\u003ccaption language=\"En\"\u003e\u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\u003cdiv class=\"CaptionContent\"\u003e\u003cp\u003eFormulation for synthesis of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite at various pH 10 and crystallization time.\u003c/p\u003e\u003c/div\u003e\u003c/caption\u003e\u003ccolgroup cols=\"5\"\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e\u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e\u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c5\" colnum=\"5\"\u003e\u003c/div\u003e\u003cthead\u003e\u003ctr\u003e\u003cth align=\"left\" colname=\"c1\"\u003e\u003cp\u003eSamples\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c2\"\u003e\u003cp\u003eCrystallization time (hour)\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c3\"\u003e\u003cp\u003eRatio of Al:P\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c4\"\u003e\u003cp\u003eHeat treatment\u003c/p\u003e\u003c/th\u003e\u003cth align=\"left\" colname=\"c5\"\u003e\u003cp\u003eReaction pH\u003c/p\u003e\u003c/th\u003e\u003c/tr\u003e\u003c/thead\u003e\u003ctbody\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 10-A\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003eAs prepared\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.3:3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003eNo heat treatment\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 10-B\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e120˚ C, 2hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.3:3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e120 ˚C, 2 hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 10-C\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e120˚ C, 12hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.3:3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e120 ˚C, 12 hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003ctr\u003e\u003ctd align=\"left\" colname=\"c1\"\u003e\u003cp\u003epH 10-D\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c2\"\u003e\u003cp\u003e120˚ C, 24hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e\u003cp\u003e1.3:3\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"left\" colname=\"c4\"\u003e\u003cp\u003e120 ˚C, 24 hours\u003c/p\u003e\u003c/td\u003e\u003ctd align=\"char\" char=\".\" colname=\"c5\"\u003e\u003cp\u003e10\u003c/p\u003e\u003c/td\u003e\u003c/tr\u003e\u003c/tbody\u003e\u003c/colgroup\u003e\u003c/table\u003e\u003c/div\u003e\u003c/p\u003e"},{"header":"Results and Discussion","content":"\u003cdiv id=\"Sec4\" class=\"Section2\"\u003e\n \u003ch2\u003eThermogravimetric (TGA) analysis\u003c/h2\u003e\n \u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e shows the TGA traces of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e samples at pH 10 for as-prepared samples and heat-treated samples at 120 ˚C for various crystallization times. Samples prepared at crystallization times of 2 and 24 hours produce maximum weight residues of 62 and 63 wt%, respectively. Meanwhile, the weight residues for as-prepared sample and the sample prepared at a crystallization time of 12 hours are 59 and 58 wt%, respectively. A longer crystallization time produces higher weight residue due to more interaction between Al-O-P after the elimination of H and OH anions that affected the Al-O-P bond. The degradation stage was similar for all crystallization time and as prepared samples. Pramanik, (2009) reported that the heat-treated PPVA at 120 ˚C for 2 hours provides the maximum bonding between PVA and the phosphate group [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e]. This result is in good agreement with Pramanik, (2009) as the PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite synthesized using a combination of refluxing, stirring, chemical precipitation and hydrothermal at 120 ˚C for 2 hours also produced maximum weight residue due to the maximum bonding between PPVA and AlPO\u003csub\u003e4\u003c/sub\u003e [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e].\u003c/p\u003e\n\u003c/div\u003e\n\u003ch3\u003eX-Ray Diffraction (XRD) Analysis\u003c/h3\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e shows the XRD patterns for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for as-prepared and heat-treated samples at 120 ˚C for various crystallization times. The XRD spectra at a range of 5 to 12˚ (110), 23.84˚ (121) and 33.92˚ (52\u0026thinsp;\u0026minus;\u0026thinsp;1) match the XRD PDF database 000-037-0189 of potassium aluminum phosphate (K\u003csub\u003e2\u003c/sub\u003e Al\u003csub\u003e2\u003c/sub\u003e P\u003csub\u003e8\u003c/sub\u003e O\u003csub\u003e28\u003c/sub\u003e) with a monoclinic crystal system. The XRD peak at an angle of 29.69˚ (220) matches the XRD PDF database 000-036-1459 of potassium aluminum phosphate (K Al P\u003csub\u003e2\u003c/sub\u003e O\u003csub\u003e7\u003c/sub\u003e) with a monoclinic crystal system. Meanwhile, 32.60˚ (060) and 33.34˚ (142) match the XRD PDF database of 98-007-4175 aluminum phosphate hydrate (1/1/2.5) with a hexagonal crystal system. The XRD peaks at 24.0996 (0 2 4), 41.4163 (2 1 28) and 42.0886 (1 2 29) also have the taranakite system that matches the PDF reference code 01-089-0895 known as potassium aluminum deuterium phosphate deuterate (K\u003csub\u003e3\u003c/sub\u003eAl\u003csub\u003e5\u003c/sub\u003e(DPO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e6\u003c/sub\u003e(PO\u003csub\u003e4\u003c/sub\u003e)\u003csub\u003e2\u003c/sub\u003e(D\u003csub\u003e2\u003c/sub\u003eO)\u003csub\u003e18\u003c/sub\u003e) and have a rhombohedral crystal system. The (110) peak shows an increase in intensity as crystallization time increases with maximum intensity observed the in sample heat-treated at 24 hours crystallization time. The peak also becomes broadened as crystallization time increases due to the interaction of PPVA and aluminum. The XRD peak at an angle of 19.27 originating from PVA and PPVA samples shows an increase in intensity from as-prepared to 12 hours crystallization time samples due to the interaction of PPVA with heat. The XRD peaks of (121), (220), (060), (5 2\u0026thinsp;\u0026minus;\u0026thinsp;1), (2 1 28) and (1 2 29) show an increase in intensity as crystallization time increases to 12 hours. Then the intensity decreases as the crystallization time reaches 24 hours. However, at peaks of 33.34˚ and 37.5˚, a decrease in peak intensity as the crystallization time increases due to the Al(OH) peak that still occurred at lower temperatures and slowly vanishes at higher temperatures or longer crystallization times. Figure \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows the XRD crystallite size distribution for various 2\u0026theta; and crystallization times. The smallest crystal size observed in samples with a crystallization time of 24 hours at a peak of 32.60˚ (060) was 26.53 nm. In general, the crystallite size decreased as the crystallization time increased. Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e summarizes the XRD data analysis of types of aluminium phosphate, the crystal system, the 2\u0026theta; position and crystal size at various crystallization times.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption language=\"En\"\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eSummary of XRD data analysis of types of aluminum phosphate, crystal system, 2\u0026theta; value, crystal size, D for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite at pH 10 with different crystallization time.\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eXRD Pdf database\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eName\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eCrystal system\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003ePosition 2\u0026theta; (˚)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\" colspan=\"4\"\u003e\n \u003cp\u003eXRD crystal size, D (nm)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epH10-A\u003c/p\u003e\n \u003cp\u003eAs prepared\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epH10-B\u003c/p\u003e\n \u003cp\u003e120˚ C,\u003c/p\u003e\n \u003cp\u003e2 hours\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epH10-C\u003c/p\u003e\n \u003cp\u003e120˚ C, 12 hours\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003epH10-D\u003c/p\u003e\n \u003cp\u003e120˚ C, 24 hours\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003e000-037-0189\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003ePotassium Aluminum Phosphate (K2 Al2 P8 O28)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"3\"\u003e\n \u003cp\u003eMonoclinic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5\u0026ndash;12 ˚ (110)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e23.84 ˚ (121)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e63.46\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52.03\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.92 ˚ (52\u0026thinsp;\u0026minus;\u0026thinsp;1)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e81.17\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e108.13\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e000-036-1459\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePotassium Aluminum Phosphate (K Al P2 O7)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMonoclinic\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e29.69 ˚ (220)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.14\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e45.88\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e64.24\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e-\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e98-007-4175\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eAluminum Phosphate Hydrate (1/1/2.5)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eHexagonal\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e32.60 ˚ (060)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e53.91\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e40.43\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35.94\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e26.53\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e33.34 ˚ (142)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e64.83\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e107.98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e64.82\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e44.29\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003e01-089-0895\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003ePotassium Aluminum Deuterium Phosphate Deuterate (K3Al5(DPO4)6(PO4)2(D2O)18)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\" rowspan=\"2\"\u003e\n \u003cp\u003eRhombohedral\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e24.0996 ˚ (0 2 4)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e63.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e79.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e79.39\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e52.07\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e41.4163 ˚ (2 1 28)\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e55.32\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47.41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e47.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e27.22\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003ch3\u003eFourier Transform Infra-Red (FTIR) spectroscopy analysis\u003c/h3\u003e\n\u003cp\u003eFigure \u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e shows the FTIR spectra for PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposites at pH 10 for as-prepared and heat-treated samples at 120 ˚C for various crystallization times. The Al-OH band was observed in as-prepared and 12 hours samples due to the OH group. Samples prepared at lower crystallization time (2 hours) and at 12 hours show no Al-OH band. All samples produce an OH peak (3371\u0026ndash;3402 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), C-OH water bending (1615\u0026ndash;1650), PO-AlPO\u003csub\u003e4\u003c/sub\u003e (1369\u0026ndash;1376 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e), C-O-P-AlPO\u003csub\u003e4\u003c/sub\u003e (1030\u0026ndash;1058 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) and O-P-O-AlPO\u003csub\u003e4\u003c/sub\u003e (541\u0026ndash;593 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e) regardless of crystallization time. Meanwhile, a few samples (2 hours crystallization time) show the Al-O-P band in the region of 2349\u0026thinsp;\u0026minus;\u0026thinsp;2090 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e. These samples show no water bending at the range of 1730\u0026ndash;1740 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003eFigures \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e (a) and (b) show the effect of crystallization time for four FTIR bands, PO-AlPO\u003csub\u003e4\u003c/sub\u003e, C-O-P-AlPO\u003csub\u003e4\u003c/sub\u003e, OH and O-P-O. Both PO-AlPO\u003csub\u003e4\u003c/sub\u003e and C-O-P-AlPO\u003csub\u003e4\u003c/sub\u003e bands are shifted to higher wavenumbers as the crystallization time increases. The OH band in Fig. \u003cspan class=\"InternalRef\"\u003e5\u003c/span\u003e (b) also had a similar trend. However, the O-P-O band is shifted to a higher wavenumber until 12 hours of crystallization time. Beyond that, the wavenumber is shifted back to a lower wavenumber. The shifted peak towards higher wavenumber shows that the OH band is influencing the PO-AlPO\u003csub\u003e4\u003c/sub\u003e and C-O-P-AlPO\u003csub\u003e4\u003c/sub\u003e bands. The amount of water is increased for samples with 2 to 12 hours of crystallization time. However, at a higher crystallization time of 24 hours, dehydration of samples has occurred that produces a peak that shifted back to the lower wavenumber. From the observation, sample prepared with 2 hours crystallization time produce more Al-O-P bonds, less Al-OH and no water bending H-O-H at a range of 1730\u0026ndash;1740 cm\u003csup\u003e\u0026minus;\u0026thinsp;1\u003c/sup\u003e.\u003c/p\u003e\n\u003ch3\u003eField Emission Scanning Electron Microscopy (FESEM) Analysis\u003c/h3\u003e\n\u003cp\u003eFigure 6 shows the FESEM images for PPVA-AlPO4 nanocomposite samples at pH 10 for as-prepared and heat-treated at 120 ˚C for various crystallization times. All samples contain spherical and layer structures. Spherical particles are observed in the prepared samples as shown in Fig.\u0026nbsp;6 (a). It is observed layer structure formation on the sample surface. The layer structure ratio increases and exists between the spherical particles as the crystallization time increases to 12 hours as shown in Fig.\u0026nbsp;6 (c). As the crystallization time increases, the ratio of component particulate and layer varies. The spherical particles are dominant at shorter crystallization times. However, at the longer crystallization time, the particles are agglomerated to form a more layered structure. A higher region of layer structure is observed at 24 hours crystallization time compared to other samples. The spherical particle reduces as the crystal nucleation and growth accelerate at longer crystallization times. Yang et al., 2014 observed similar results that the crystallization time is only influence the aspect ratio and uniformity of particles [\u003cspan class=\"CitationRef\"\u003e12\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eFigure 7 shows the FESEM micrographs (200x magnification) of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples at pH 10 for (a) as-prepared and heat-treated samples at 120 ˚C for various crystallization time: (b) 2, (c) 12 and (d) 24 hours with measured sizes. Figure 7(a) shows the nanoparticles are homogeneously distributed with a spherical shape and a size less than 50 nm. The presence of immiscible of taranakite layer is also observed. At higher magnification (200x), the image shows agglomeration of AlPO\u003csub\u003e4\u003c/sub\u003e particles into various sizes (16\u0026ndash;20 nm). This size is in different value from the calculated crystallite size through XRD. However, they are still in a nano region. There is no polymer phase observed in the system. The size of AlPO\u003csub\u003e4\u003c/sub\u003e nanoparticles is smaller and more homogeneously distributed as compared to AlPO\u003csub\u003e4\u003c/sub\u003e nanoparticles obtained by Palacios et al., (2013), which were synthesis at pH 6 for 480 min [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. The homogeneous particle distribution with smaller size is due to the effectiveness of PPVA as the encapsulating material for better interfacial bonding through its pendant groups with aluminum phosphate. This is in good agreement with Pramanik et al. (2009) that PPVA provides an effective method for better dispersion of nanoparticles in the polymer matrix with a strong particle polymer interfacial bonding through its phosphate groups [\u003cspan class=\"CitationRef\"\u003e11\u003c/span\u003e]. The nuclei grow uniformly by diffusion of solutes from the solution to its surface until they reach the final shape. However, the uniform particles are also obtained after the occurrence of multiple nucleation. The observed nanoparticles are a result of microstructure development, where agglomeration of small particles accumulated and formed bigger particles. FESEM images show that AlPO\u003csub\u003e4\u003c/sub\u003e nanoparticles are developed from the agglomeration of very small particles. PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite is also observed to contain the immiscible layer and nanoparticle which is in good agreement with the XRD pattern (Fig. \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). From Ostwald ripening and Wuff construction theory, the particle size in the nanometer range and exhibiting irregular geometry will experience more stress and strain on the surface [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e]. However, for larger sizes of spherical particles, the stress and strain are less [\u003cspan class=\"CitationRef\"\u003e14\u003c/span\u003e].\u003c/p\u003e\n\u003cp\u003eSamples prepared at 2 hours crystallization (Fig.\u0026nbsp;7(b)) time show layers mixed with spherical and nanotube structures are observed at pH 10. The average particle size is less than 15 nm. Figures\u0026nbsp;7(c) show the FESEM micrographs of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposites prepared at 12 hours crystallization time. A sample prepared at pH 10 shows a bulky structure of heterogeneous shape of AlPO\u003csub\u003e4\u003c/sub\u003e with a distribution of spherical nanoparticles on the surface. The average particle size for samples prepared at pH 10 is less than 10 nm. Figures 7(d) the FESEM micrographs of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite samples prepared at 24 hours crystallization time. Spherical nanoparticles are distributed on the surface of layer structures as observed at pH 10. Also being observed is a small ratio of nanotubes co-existing with spherical and layer structures. A sample prepared at a shorter crystallization time of 2 hours shows homogeneous nano spherical particles at a lower pH. However, it produces a mixture of spherical and entangled aligned nanoparticles forming a shape similar to a nanotube at higher pH. Yet, there is no study to confirm the occurrence of holes in similar nanotube structures. The average particle size for samples prepared at pH 10 is under 13 nm.Kawamura et al., (2007), reported that by controlling the pH and temperature, the number of H\u003csup\u003e+\u003c/sup\u003e and OH\u003csup\u003e\u0026minus;\u003c/sup\u003e ions thus affected the morphologies of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposites that can be controlled [\u003cspan class=\"CitationRef\"\u003e15\u003c/span\u003e]. Our observation suggests that at shorter crystallization times, morphologies are affected by pH but not the size of particles. However, at longer crystallization times, pH variation will vary the geometrical structure and the size of spherical particles.Palacios et al., (2013) also reported a similar observation, nevertheless they observed an increase in particle size with an increase in crystallization time [\u003cspan class=\"CitationRef\"\u003e13\u003c/span\u003e]. Additionally, they also observed an agglomeration and heterogeneous morphology phase distribution as crystallization time increases.Yang \u0026amp; Kau, (2005) reported that the dehydration and condensation of the EO fraction used to synthesize AlPO\u003csub\u003e4\u003c/sub\u003e nanoparticles produced a chain shape [\u003cspan class=\"CitationRef\"\u003e16\u003c/span\u003e]. Thus, heat treatment does affect the morphologies of AlPO\u003csub\u003e4\u003c/sub\u003e. Other than that, they elaborated on the phosphate ion condensation/polymerization leading to the formation of condensed phosphates, which can be linear, cyclic and/or cross-linked/branched phosphates formed upon drying at higher temperatures. This observation explained the occurrence of nanotube structure that appeared at pH 10 after the autoclaving process.Burrell et al., (1999) reported that various morphologies occurred after autoclaving due to the occurrence of double hydroxide bridges during the autoclaving process [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e]. This double hydroxide bridge varies by the number of H\u003csup\u003e+\u003c/sup\u003e and OH\u003csup\u003e\u0026minus;\u003c/sup\u003e ions present that may also contribute to the formation of nanotube structure [\u003cspan class=\"CitationRef\"\u003e17\u003c/span\u003e].\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003eThe effect of crystallization time on PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite analyzed from thermal analysis shows maximum weight residue at crystallization times of 2 and 24 hours. The XRD spherical particle size calculation shows that the average particle size decreases as the crystallization time decreases. The broad peak becoming more intense shows an increase in crystallinity of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite. The FTIR analysis shows intense C-O-P-Al and O-P-O-Al peaks at both 2 and 12 hours of crystallization time due to the occurrence of more Al-PO\u003csub\u003e4\u003c/sub\u003e compared to Al-OH. At crystallization time, 2 hours shows no Al-OH peak at the water region, which suggests the best condition to produce PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite. However, the FESEM micrograph analysis observed varying interesting morphology of PPVA-AlPO\u003csub\u003e4\u003c/sub\u003e nanocomposite as crystallization time increase. Sample preparation at the crystallization times of 2 and 24 hours shows growth of nanotubes at high alkaline regions. As a conclusion, to produce a better interaction of PPVA and aluminum phosphate with unique morphology, the best crystallization time would be 2 hours.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003eAcknowledgement\u003c/p\u003e\n\u003cp\u003eThe authors acknowledge the Malaysian Institute of Marine Engineering Technology and the Universiti\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eMalaya.\u003c/p\u003e\n\u003cp\u003eFunding Declaration\u003c/p\u003e\n\u003cp\u003eThe authors hereby declared that there is no funding related to the work reported in this manuscript.\u003c/p\u003e\n\u003cp\u003eCompeting Interests\u003c/p\u003e\n\u003cp\u003eAuthors are required to disclose financial or non-financial interests that are directly or indirectly related to the work submitted for publication. Please refer to \u0026ldquo;Competing Interests and Funding\u0026rdquo; below for more information on how to complete this section.\u003c/p\u003e\n\u003cp\u003eAuthor Contributions Statement\u003c/p\u003e\n\u003cp\u003eAsmalina Mohamed Saat performed the measurements, planning and supervised the work, processed the experimental data, performed the analysis, drafted the manuscript and designed the figures. Nor Aliya Hamizi and Mohd Rafie Johan aided in interpreting the results and worked on the manuscript. All authors discussed the results and commented on the manuscript.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n \u003cli\u003eA. M. Saat \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Influence of reaction ph towards the physicochemical characteristics of phosphorylated polyvinyl alcohol-aluminum hosphate nanocomposite,\u0026rdquo; \u003cem\u003eCoatings\u003c/em\u003e, vol. 11, no. 9, Sep. 2021, doi: 10.3390/coatings11091105.\u003c/li\u003e\n \u003cli\u003eA. M. Saat, N. A. Latiff, S. Yaakup, and M. R. B. Johan, \u0026ldquo;Synthesis and characterisation of composite partially phosphorylated polyvinyl alcohol-aluminium phosphate as protective coating,\u0026rdquo; \u003cem\u003eMaterials Research Innovations\u003c/em\u003e, vol. 18, 2014, doi: 10.1179/1432891714Z.000000000974.\u003c/li\u003e\n \u003cli\u003eM. Mahardika \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Nanocellulose reinforced polyvinyl alcohol-based bio-nanocomposite films: improved mechanical, UV-light barrier, and thermal properties,\u0026rdquo; \u003cem\u003eRSC Adv\u003c/em\u003e, vol. 14, no. 32, pp. 23232\u0026ndash;23239, Jul. 2024, doi: 10.1039/d4ra04205k.\u003c/li\u003e\n \u003cli\u003eH. Kalita, P. Pal, S. Dhara, and A. Pathak, \u0026ldquo;Fabrication and characterization of polyvinyl alcohol/metal (Ca, Mg, Ti) doped zirconium phosphate nanocomposite films for scaffold-guided tissue engineering application,\u0026rdquo; \u003cem\u003eMaterials Science and Engineering: C\u003c/em\u003e, vol. 71, pp. 363\u0026ndash;371, Feb. 2017, doi: 10.1016/J.MSEC.2016.09.063.\u003c/li\u003e\n \u003cli\u003eR. Sigwadi and F. Nemavhola, \u0026ldquo;Polyvinyl Alcohol/Nafion\u0026reg;\u0026ndash;Zirconia Phosphate Nanocomposite Membranes for Polymer Electrolyte Membrane Fuel Cell Applications: Synthesis and Characterisation,\u0026rdquo; \u003cem\u003eMembranes (Basel)\u003c/em\u003e, vol. 13, no. 12, Dec. 2023, doi: 10.3390/membranes13120887.\u003c/li\u003e\n \u003cli\u003eS. Sani, R. Adnan, W.-D. Oh, and A. Iqbal, \u0026ldquo;Comparison of the Surface Properties of Hydrothermally Synthesised Fe3O4@C Nanocomposites at Variable Reaction Times,\u0026rdquo; Nanomaterials, vol. 11, no. 10, p. 2742, Oct. 2021, doi: 10.3390/nano11102742.\u003c/li\u003e\n \u003cli\u003eM. H. Ashery, E. M. Elsehly, M. Elnouby, and E. M. EL-Maghraby, \u0026ldquo;Controlled synthesis of MWCNTs/V2O5 nanocomposite by hydrothermal approach for adsorption and photodegradation processes,\u0026rdquo; Water Science \u0026amp; Technology, vol. 88, no. 2, pp. 392\u0026ndash;407, Jul. 2023, doi: 10.2166/wst.2023.217.\u003c/li\u003e\n \u003cli\u003eO. Gazil, D. Alonso Cerr\u0026oacute;n-Infantes, N. Virgilio, and M. M. Unterlass, \u0026ldquo;Hydrothermal synthesis of metal nanoparticles@hydrogels and statistical evaluation of reaction conditions\u0026rsquo; effects on nanoparticle morphologies,\u0026rdquo; Nanoscale, vol. 16, no. 38, pp. 17778\u0026ndash;17792, 2024, doi: 10.1039/D4NR00581C.\u003c/li\u003e\n \u003cli\u003eG. Seong and J. C. Rend\u0026oacute;n-Angeles, Eds., \u003cem\u003eHydrothermal Synthesis of Nanoparticles\u003c/em\u003e. MDPI, 2023. doi: 10.3390/books978-3-0365-8065-4.\u003c/li\u003e\n \u003cli\u003eJ. C. Rend\u0026oacute;n-Angeles and G. Seong, \u0026ldquo;Hydrothermal Synthesis of Nanoparticles,\u0026rdquo; \u003cem\u003eNanomaterials\u003c/em\u003e, vol. 13, no. 9, p. 1463, Apr. 2023, doi: 10.3390/nano13091463.\u003c/li\u003e\n \u003cli\u003eP. Pramanik, \u0026ldquo;Some simple chemistry for exotic polymers,\u0026rdquo; \u003cem\u003eProceedings of the 17th International conference composite/nano engineering (ICCE \u0026rsquo;09),World Journal of Engineering, Honolulu, Hawaii, USA, 2009.\u003c/em\u003e, vol. 6, pp. 1\u0026ndash;2, 2009.\u003c/li\u003e\n \u003cli\u003eW. Yang \u003cem\u003eet al.\u003c/em\u003e, \u0026ldquo;Synthesis and crystal morphology control of AlPO4-5 molecular sieves by microwave irradiation,\u0026rdquo; \u003cem\u003eSolid State Sci\u003c/em\u003e, vol. 29, pp. 41\u0026ndash;47, Mar. 2014, doi: 10.1016/j.solidstatesciences.2014.01.004.\u003c/li\u003e\n \u003cli\u003eE. Palacios, P. Leret, M. J. de la Mata, J. F. Fern\u0026aacute;ndez, A. H. De Aza, and M. a. Rodr\u0026iacute;guez, \u0026ldquo;Influence of the pH and ageing time on the acid aluminum phosphate synthesized by precipitation,\u0026rdquo; \u003cem\u003eCrystEngComm\u003c/em\u003e, vol. 15, no. 17, p. 3359, 2013, doi: 10.1039/c3ce00011g.\u003c/li\u003e\n \u003cli\u003eP. W. Voorhees, \u0026ldquo;Ostwald ripening of two-phase mixtures,\u0026rdquo; Annual Review of Materials Science, vol. 22(1), pp. 197-215, 1992.\u003c/li\u003e\n \u003cli\u003eK. Kawamura, K. Shibuya, and A. Okuwaki, \u0026ldquo;Morphology of aluminum phosphate by the Al-EDTA mediated particle formation in aqueous solutions at high temperatures,\u0026rdquo; Mater Res Bull, vol. 42, no. 2, pp. 256\u0026ndash;264, Feb. 2007, doi: 10.1016/j.materresbull.2006.06.005.\u003c/li\u003e\n \u003cli\u003eC.-S. Yang and K.-Y. Kau, \u0026ldquo;Synthesis of Morphology Processable a-AlPO 4 Nanoparticles , Nanowires and Multi-strand Nano-ropes,\u0026rdquo; \u003cem\u003eJournal of the Chinese Chemical Society\u003c/em\u003e, vol. 52, pp. 477\u0026ndash;487, 2005.\u003c/li\u003e\n \u003cli\u003eL. S. Burrell, E. B. Lindblad, J. L. White, and S. L. Hem, \u0026ldquo;Stability of aluminium-containing adjuvants to autoclaving,\u0026rdquo; \u003cem\u003eVaccine\u003c/em\u003e, vol. 17, no. 20\u0026ndash;21, pp. 2599\u0026ndash;2603, Jun. 1999, doi: 10.1016/S0264-410X(99)00051-1.\u003c/li\u003e\n\u003c/ol\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":"","lastPublishedDoi":"10.21203/rs.3.rs-6900538/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-6900538/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe hydrothermal method is now widely used in the synthesis of nanomaterials because it is simple, easy and inexpensive to produce. The transformation of nanomaterials into a crystalline structure can be easily modified at different temperatures, pressures and heating modes (conduction, convection or microwaves). This study investigates the effects of pH and crystallization time on the evolution of the microstructure of phosphorylated poly(vinyl alcohol)-aluminum phosphate (PPVA-AlPO4) nanocomposite. The thermal stability, structure and surface morphology were recorded using TGA, FTIR, XRD and FESEM analyses. The microstructure evolves into spherical nanoparticles at low pH and nanowires at highly alkaline conditions. The particle size of the observed nanocomposite decreased with increasing crystallization time. At a crystallization time of two hours, the structure was found to have no OH peak in the water region and the intensity of the C-O-P and O-P-O-Al peaks increased. As a conclusion to produce high crystallinity and uniform distribution of PPVA-AlPO4 nanocomposite nanoparticles, a reaction at a pH of 10 and a crystallization time of 2 hours is suggested.\u003c/p\u003e","manuscriptTitle":"Effect of crystallization time on the properties of PPVA-AlPO 4 nanocomposite synthesis by hydrothermal method at various pH","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2025-07-11 07:48:28","doi":"10.21203/rs.3.rs-6900538/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":"9e968c9f-630b-490b-9081-7c9a009fcbac","owner":[],"postedDate":"July 11th, 2025","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2025-07-15T14:53:47+00:00","versionOfRecord":[],"versionCreatedAt":"2025-07-11 07:48:28","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-6900538","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-6900538","identity":"rs-6900538","version":["v1"]},"buildId":"8U1c8b4HqxoKbykW_rLl7","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}