Development of Hybrid Titania/Polybenzoxazine Composite for Enhance Thermo-Mechanical, Flame Retardancy and Dielectric Properties

Development of Hybrid Titania/Polybenzoxazine Composite for Enhance Thermo-Mechanical, Flame Retardancy and Dielectric 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 Development of Hybrid Titania/Polybenzoxazine Composite for Enhance Thermo-Mechanical, Flame Retardancy and Dielectric Properties shakilaparveen asrafali This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-1434024/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 Polybenzoxazines (Pbzs) are recently developed class of thermosetting polymeric materials possessing low surface free energy with non-fluorine or non-silicon content. In the present study, a new type of Pbz-BN/TiO 2 composites were fabricated using benzoxazine monomer [bis(6-phenyl diazenyl-3-phenoxy-3,4-dihydro-2H-1,3-benzoxazinyl) benzonitrile] and inorganic TiO 2 fillers by a simple and inexpensive process. Thermal curing method was found to be effective for preparing superhydrophobic surfaces combining low surface energy and surface roughness. The presence of benzonitrile group in the benzoxazine monomer paves way for accelerating the curing of the benzoxazine monomer as shown by the DSC analysis. The as-prepared Pbz/TiO 2 surfaces containing 5 wt% of TiO 2 generated a superhydrophobic surface exhibiting static water contact angle (SWCA) of 146°. In addition to it, the effect of inorganic fillers on the thermal, mechanical and dielectric properties of the Pbz/TiO 2 composites was investigated in detail. polybenzoxazines benzonitrile TiO2 fillers composites superhydrophobic Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Introduction Polybenzoxazine (Pbz), as a new class of thermosetting phenolic resins has been developed to overcome the shortcomings of traditional phenolic resin, while keeping the advantages of cost effectiveness, heat resistance and flame retardancy. Benzoxazine based thermosets exhibit high glass transition temperature and high modulus even though they have relatively low crosslink densities owing to strong hydrogen bonding restricting segmental mobility and impeding network formation 1 – 5 . In spite of these, Pbz is considered as a new class of low surface energy materials and exhibits a large number of interesting properties, such as near zero shrinkage during curing, high carbon content, low water absorption, high thermal stability, excellent electrical properties etc. Low surface energy is important for many practical applications in coatings, self-cleaning materials and biomaterials 6 – 9 . Several studies have been conducted to improve the mechanical properties of polymers, such as strength, toughness and elastic modulus, among which the combination of nanoparticles (NPs) is one of the most current research topics. Since NPs are usually aggregated due to the strong van der Waals force, it is very difficult to achieve mono-dispersity in a resin matrix at the nanoscale. Agglomerated fillers not only suffers the mechanical properties of the cured matrix, but also act as initiation points of cracks and fractures, which even deteriorate the mechanical properties. In other words, one of the critical issues is to achieve a non-aggregated dispersion of the integrated NPs to impart the polymer matrix its remarkable mechanical, electrical and thermal properties. Their dispersion characteristics and interfacial adhesion can be improved by modifying the NP surface with suitable dispersants or polymer coating 9 – 16 . Modification of nano fillers with functional benzoxazine monomer (Bzo-BN) has proven to be a promising approach to prepare nanocomposites by exploiting high flexibility of benzoxazine molecular design by synthesizing titania/polybenzoxazine nanocomposites via thermal curing process. Transparent hybrid films were obtained, suggesting dispersion of nano sized titania particles in a polybenzoxazine matrix. Novel polymer composite with nano-TiO 2 content reinforced with polybenzoxazine were prepared. The adhesion between nano-TiO 2 and Pbz-BN was found to be strong, and the distribution of nano fillers was relatively uniform; a novel benzoxazine with benzonitrile functionalization (Bzo-BN) was prepared and blended with TiO 2 (with different ratios) leading to the formation of highly dispersible organic/inorganic polybenzoxazine/TiO 2 hybrid composites 17 – 24 . The effect of dispersion of different wt% of TiO 2 particles in benzoxazine was investigated by analyzing their polymer properties, viz., mechanical, thermal, water resistance and dielectric properties. TiO 2 was used in this work as it has a linear coefficient of thermal expansion closer to that of the polymer matrix and other excellent properties, such as high strength and surface toughness and excellent wear resistance. Although several studies on the effect of various dispersants on the mechanical behavior of polybenzoxazine nanocomposites have been reported previously, no studies based on benzoxazine/TiO 2 matrices have been reported. Therefore, our preparation and evaluation procedure provides a good way to facilitate the dispersion of inorganic NPs with benzoxazine dispersants and to further improve the mechanical properties of benzoxazine/TiO 2 composites. Experimental Materials and methods The materials, instrumentation methods, synthesis of precursors, i.e., 4-(phenyl diazenyl) phenol [PAP] and 4,4’ bis(4-aminophenoxy) benzonitrile [APBN] and structure analysis of these precursors are given in the ESI. Synthesis of bis(6-phenyl diazenyl-3-phenoxy-3,4-dihydro-2H-1,3-benzoxazinyl) benzonitrile [Bzo-BN] To start with, paraformaldehyde (1.8 g, 0.06 mol) was dissolved in DMSO (50 mL) at 100 ℃. To the dissolved solution, the synthesized diamine (APBN, 3.2 g, 0.01 mol) and the phenol (PAP, 3.9 g, 0.02 mol) were added in parts and the reaction mixture was further increased to 130 ℃. After completion of reaction, the reaction mixture was allowed to reach room temperature and the product precipitated in 1N NaOH solution. The collected precipitate was water washed to remove any un-reactants, filtered and dried at 60 ℃ to afford brown powder of Bzo-BN monomer [Scheme 1]. Yield: 82% FT-IR (KBr, cm -1 ): 936 (stretching vibrations of the oxazine ring), 1256 & 1045 (asymmetric and symmetric stretching vibrations of C-O-C), 1177 (stretching of C-N-C), 1340 (CH 2 wagging), 2246 ( -CN stretching vibrations), 1445 (trans N=N stretching vibrations); 1 H-NMR (CDCl 3 , ppm): 5.4 (s, H a , 4H), 4.6 (s, H b , 4H) and 6.5–8.0 (m, aromatic protons); 13 C-NMR CDCl 3 , ppm): 79 (O-CH 2 -N), 50 (Ar-CH 2 -N), 115 (-CN), 94 (Ar (C)-CN) and 110–155 (aromatic carbons). Preparation of Pbz-BN/TiO 2 composites Pbz-BN/TiO 2 composites with varying ratios of TiO 2 were prepared. Briefly, the synthesized Bzo monomer and TiO 2 (1 wt% of Bzo-BN) was mixed with THF and stirred well to form a homogeneous solution. This solution was then poured onto petridish, pretreated with dichlorodimethyl silane (for easy release of the cured film) and then cured maintaining the temperature at 250 ℃ for 3h. The cured films were then taken out with care. Pbz/TiO 2 composite thus prepared was denoted as Pbz-BN/T1. Similarly, other ratios of Pbz/TiO 2 composites were denoted as Pbz-BN/T0; Pbz-BN/T3 and Pbz-BN/T5, respectively with varying the weight ratio of TiO 2 . Results And Discussions Structural analysis of benzoxazine monomer [Bzo-BN] The FT-IR spectra of the synthesized benzoxazine monomer [Bzo-BN] was shown in Figure 1. It can be seen from the figures that the benzoxazine ring is characterized by the absorption bands between 936 cm -1 , due to the stretching vibrations of the oxazine ring. Moreover, the benzoxazine ring also gave its characteristic absorption band at 1219 cm -1 , 1021 cm -1 due to the asymmetric and symmetric stretching vibrations of the C-O-C bond, stretching vibrations of the C-N-C bond respectively 25 . The nitrile (-CN) group show their characteristic absorption bands at 2246 cm -1 . Figure 2, illustrates the 1 H-NMR and 13 C-NMR spectra of the benzoxazine monomer Bzo-BN. The oxazine ring protons (H a , O-CH 2 -N and H b , Ar-CH 2 -N) show two singlets at 5.4 and 4.6 ppm, respectively 26-28 . The aromatic ring protons are located between 6.5 - 8.0 ppm. The 13 C-NMR spectrum shows the characteristic carbon resonances of Bzo-BN. The methylene carbons [O-CH 2 -N (C 1 ) and Ar-CH 2 -N (C 2 )] of the oxazine ring resonate at 79 and 50 ppm, respectively. The carbon of the benzonitrile group (C 3 ) resonates at 115 ppm. And the aromatic carbon attached to the benzonitrile group (C4) resonates at 94 ppm 29 . All other aromatic carbons resonate between 110 - 155 ppm, respectively. Polymerization behavior of hybrids DSC of the hybrids was performed to study the polymerization behavior of benzoxazine monomer in presence of TiO 2 by monitoring the typical exothermic peak attributed to the ring opening polymerization of benzoxazine (Bzo-BN) and their hybrids (Bzo-BN/T0-T5). DSC showed that the neat benzoxazine monomer exhibits an exothermic curve with T onset at 224 ℃, T max at 243 ℃ and T final at 256 ℃. In comparison, for the hybrids, the exothermic curve shows that T onset slightly shifted to lower temperature (218 ℃) and T max and T final shifted to 251 and 262 ℃, respectively. This result indicates that the ring opening polymerization of benzoxazine monomer has been accelerated by the presence of nitrile group (act as a catalyst) and thus lowers its onset of curing temperature. The addition of TiO 2 particles into the Bzo monomer shifts the maximum and final curing temperature to higher value, which could be due to the trapped TiO 2 particles inside the monomer. Moreover, the ΔH value of Bzo-BN/TiO 2 hybrids decreases with increasing TiO 2 content. This is due to the fact that with increased TiO 2 content, the Bzo content in the Bzo-BN/TiO 2 hybrid decreased obviously, thus reducing their enthalpy values. Similar exothermic curing behavior was observed for BA-a/inorganic nano fibers (30 wt%), where, the maximum curing temperature of neat BA-a (240 ℃) was shifted to 250 ℃ with incorporation of the inorganic materials 30,31 . Table 1 Data from DSC thermograms of Bzo-BN/TiO 2 hybrids S.No. Sample TiO 2 ratio T onset ( o C) T max ( o C) T final ( o C) 1 Bzo-BN/TiO 2 0 224 243 256 2 1 223 245 258 3 3 220 248 261 4 5 218 251 262 Morphology of PBz-BP/TiO 2 composites Figure 4 shows the SEM micrographs of PBz-BN/TiO 2 composites. The smooth surface of pure polybenzoxazine is clearly visible from the figure. As the titanium content increases (from 1 to 5% by weight), the surface of the composites loses its smoothness and becomes rough. It also shows the formation of homogeneous hybrid material and fine dispersion of titanium particles. The small size of the titanium particles may be responsible for the transparency of the hybrid materials 32 . As the TiO 2 content increases to 5% loading, few voids or gaps appear on the surface of the composites. AFM images (Fig. 5) of polybenzoxazine and their composites show that the size of the nodules formed by the Pbz-TiO 2 particles is uniform and has a uniform distribution, as seen in the SEM images. The surface roughness of polybenzoxazine-silica hybrids was calculated from AFM measurements using the following equation 33 , R t = R p + R v Where R t is the total roughness of the measured sample, R p is the maximum peak height of the profile, and R v is the maximum valley depth of the profile. The total roughness was found to be 8, 83, 109, and 128 nm for Pbz-BP:T0, Pbz-BP:T1, Pbz-BP:T3, and Pbz-BP:T5, respectively. The roughness value increases with increasing titanium content from 1 to 5 wt%, which is consistent with the AFM images. Surface Properties of the polybenzoxazine-titania hybrids As is known, superhydrophobic surfaces can be prepared by combining low surface area and free energy materials with rough structures. In this case, Pbzo-BN with a network of hydrogen bonds and nitrile structures were used as a low surface area and free energy material 34 . The addition of TiO 2 NPs was able to form rough structures. Figure 6 shows the WCAs of neat polybenzoxazine and polybenzoxazine-titania hybrid [Pbz-BP:T1, Pbz-BP:T3 and Pbz-BP:T5] coatings with different mass ratios of TiO 2 NPs. The pure Pbz coating showed hydrophobicity with a WCA of 87°. With the increase of the additional amount of TiO 2 NPs, the hydrophobicity of the Pbz/TiO 2 also increased significantly with a linear increase in WCA from 87 to 146 °C. The hydrophobicity of polybenzoxazine was improved by incorporating TiO 2 nanoparticles even at low concentrations (e.g. 5 wt% TiO 2 ). The increased hydrophobicity of the [Pbz-BP:T5] hybrid is attributed to the air trapped in the voids of the rough surface and preventing water from entering the nanoparticles, leading to an increase in the contact angle with water 35 . Dynamic mechanical Properties of titanium-modified polybenzoxazine hybrids The dynamic mechanical properties of the hybrid materials in comparison to neat polybenzoxazine were examined. Fig. 7 shows the storage modulus (E′) and loss modulus (E″) as a function of temperature. The storage modulus of the neat Pbz drops slowly up to 125 °C, after which there is a sharp drop with a glass transition temperature (T g ) of 147 °C obtained from the maximum of loss modulus. The storage moduli of the composites in the glassy state increase with the inclusion of titanium particles, and rise more on further increasing the content of titanium in the hybrids 36-38 . This behavior indicates that the dispersed titanium nanoparticles are effective to reinforce polybenzoxazine matrix. The drastic improvement of the storage modulus of polybenzoxazine by hybridization with small amount of titanium nanoparticles (5%) can be attributed to the reinforcing role of the titanium nanoparticles and the increase of the polymerization degree of polybenzoxazine via their nitrile group on the ring opening polymerization similar to the role of silica, clay and other inorganic nanomaterials on polybenzoxazines nanocomposites as previously reported 37,39 . Also, the hybrids show higher T g than the neat resin. The T g of pure polybenzoxazine was found to be 147 °C; but for the composites, the T g increased with increasing nano filler content (T g of Pbz-BP/T5 is 164 °C). The hard and rigid inorganic regions create an obstacle to the movements of random chain segments in the matrix. This restricted mobility of the segmental molecular chains results with an increased T g values. A similar increase in T g values is observed in PBA-a composites with other inorganic nanofibers, ranging between 185 and 193 °C 40-43 . Table 2 DMA data of Pbz-BN/TiO 2 composites S.No. Sample TiO 2 ratio DMA Storage modulus T g ( o C) CLD *10 5 mol/m 3 1 PBz-BN/TiO 2 0 2.81 147 3.7 2 1 3.15 151 4.1 3 3 3.21 157 4.2 4 5 3.26 164 4.3 Cross-link density of Pbz/TiO 2 composites The cross-link density (CLD), γ c is the number of network chain molecules per unit volume of the cured polymer. The cross-linking density of highly cross-linked thermoset materials can be determined by modulus measurements using the modulus constitutive equation given below 44 , γ c = ɛ'/3RT Where, ɛ' = storage tensile modulus (from DMA) T = temperature in K corresponding to the value of the storage modulus R = gas constant Table 2 shows the interconnect density of the Pbz/TiO 2 composites. The crosslinking density of the pure polymer, i.e. Pbz-BN/T0, was found to be 3.7*10 -5 mol m -3 , while the crosslinking density of the composite, i.e. Pbz-BN/T5, was found to be 4.3*10 -5 mol m -3 . It can be seen that the crosslinking density obviously increases with the increase in the nanoparticle content in the composites. The main reason is that the nanoparticles behave as natural cross-linkers by forming intermolecular hydrogen bonds between the hydroxyl groups of the nanoparticles and the -OH, -CN, of the polybenzoxazine(s), thus limiting their molecular motion 45,46 . Thermal stability of Pbz/TiO 2 composites The thermal stability of the hybrids was studied by thermogravimetric analysis to investigate the effect of dispersed titanium particles on the thermal stability of the polybenzoxazine matrix. Figure 8 shows the TGA profiles under nitrogen atmosphere of pure Pbz and the composites containing various percentages of titanium. For pure Pbz, T 5 and T 10 are 326 & 354 °C with a carbon yield of 42.6%. The incorporation of titanium particles in the Pbz matrix led to an increase in thermal stability. For example, the carbon yield increased from 42.6 to46.4, 51.2 and 53.7% with the addition of 0, 1, 3 and 5 wt% titania, suggesting that the dispersed titanium particles in the matrix act as a thermal insulator to protect the Pbz matrix. Also, the composites also contain nitrile group, by which the thermal stability showed a greater improvement. This could be attributed to the maximized adhesion between the organic (Pbz) and inorganic (titanium) sites, which further protect the organic matrix with thermal insulation 47-49 . Table 3 TGA data of Pbz-BN/TiO 2 composites S.No. Sample TiO 2 ratio T i ( ℃ ) T 5 ( ℃ ) T 10 ( ℃ ) CY LOI 1 PBz-BN/TiO 2 0 286 326 354 42.6 34.5 2 1 296 351 374 46.4 36.1 3 3 308 364 386 51.2 38.0 4 5 313 378 403 53.7 39.0 Flame retardancy of Pbz/TiO 2 composites The flammability resistance of pure Pbz and Pbz-TiO 2 composites is explained as a function of the limiting oxygen index (LOI) value. One way to calculate the LOI is by TGA analysis, knowing their corresponding carbon yield values. van Krevelen and Hofytzer used the equation 50 given below to calculate the LOI, LOI=17.5+0.4*CY Where, LOI is the oxygen limit index, CY is the carbon yield (from TGA data). The value of LOI for the pure Pbz-BN polymer was 34.5. And their composites showed LOI values of 36.1, 38.0 and 39.0 for Pbz-BN/T1, Pbz-BN/T3 and Pbz-BN/T5, respectively (Table 3). It could be observed that the LOI value of polybenzoxazine and their composites were higher than the threshold value (26). This clearly indicates that the incorporation of TiO 2 nanoparticles in the Pbz system results in thermosets with good self-extinguishing and flame retardant properties. Dielectric properties of Pbz/TiO 2 composites Dielectric materials can be used to store electrical energy in the form of charge separation when the electron distributions around their constituent atoms or molecules are polarized by an external electric field. The dielectric constant is directly related to the polarizability of the material and is therefore highly dependent on its chemical structure. Figure 9 shows the values of the dielectric constant and the dielectric loss of Pbz/TiO 2 composites. The values of dielectric constant and dielectric loss were found to be in the range of 3.2 - 2.9 and 0.94 - 0.78, respectively for Pbz-BN/TiO 2 composites, respectively (Table 4). Composites differ from micro composites in three aspects: they contain small amounts of fillers, the filler particles have sizes in the order of nanometers, and the interface between the filler and the polymer is large. Nanoparticles reduce the movement of the polymer chain by physical bonding 51 . The mobility of the charge carriers, also decreased with particle loading, suggesting that the nanoparticles disperse the carriers by reducing their mobility, leading to a decrease in permeability with increasing frequency 52 . Table 4 Dielectric data of Pbz-BN/TiO 2 composites S.No. Sample TiO 2 ratio Dieletric Constant Loss 1 PBz-BN/TiO 2 0 3.2 0.94 2 1 3.1 0.93 3 3 3.0 0.87 4 5 2.9 0.78 Conclusion In this study, a novel benzoxazine monomer (Bzo-BN) containing benzonitrile moiety was synthesized using a simple Mannich condensation reaction. Titania particles (with varying contents) were directly mixed with the Bzo monomer and thermally cured undergoing self-polymerization to produce Pbz/TiO 2 composites. The curing behavior of the Bzo monomer and their hybrids with TiO2 has been much accelerated by the presence of benzonitrile group. A sharp increase in the contact angle for the composite Pbz-BN/T5 (146°) was observed even with a very less amount of titania loading (~ 5 wt%). In spite of this, a drastic improvement in thermal i.e., T5 = 378 ℃; T10 = 403 ℃, mechanical i.e., E' = 3.26 GPa and dielectric i.e., ɛ' = 2.9 was obtained for Pbz-BN/T5. These improvements are due to the difference in surface energies between Pbz and inorganic fillers that generated surfaces with various roughness an caused important ameliorations in the thermo-mechanic and dielectric properties of the neat Pbz resin. 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Angewandte. Chemie. 45 , 2248–2251 (2006) Y.C. Chen, H.C. Lin, Y.D. Lee, The effects of phenyltrimethoxysilane coupling agents on properties of PTFE/Silica composites. J. Polym. Res. 11 , 1–7 (2004) N.N. Ghosh, B. Kiskan, Y. Yagci, Polybenzoxazines-new high performance thermosetting resins: Synthesis and properties. Prog. Polym. Sci. 32 , 1344–1391 (2007) Y. Yagci, B. Kiskan, N.N. Ghosh, Recent advancement on polybenzoxazine a newly developed high performance thermoset. J. Polym. Science: Part A: Polym. Chem. 47 , 5565–5576 (2009) B. Kiskan, B. Gacal, M. Atilla Tasdelen, D. Colak, Y. Yagci, Design and synthesis of thermally curable polymers with benzoxazine functionalities, Macromolecular Symposia, 2006, 245–246, 27–33 D.W. van Krevelen, Some basic aspects of flame resistance of polymeric materials. Polymer 16 , 615–620 (1975) Y. Liu, J. Zhang, Z. Li, X. Luo, S. Jing, Run, M., A pair of benzoxazine isomers from o-allylphenol and 4,4’-diaminodiphenyl ether: Synthesis, polymerization behavior, and thermal properties. Polymer 55 , 1688–1697 (2014) J. Liu, X. Lu, Z. Xin, C. Zhou, Synthesis and surface properties of low surface free energy silane-functional polybenzoxazine films. Langmuir 29 , 411–416 (2013) Supplementary Files Supplementarydata.docx 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-1434024","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":90881640,"identity":"01999815-c304-4d57-9322-df06e8c59cd6","order_by":0,"name":"shakilaparveen asrafali","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAA9klEQVRIiWNgGAWjYDACCQZmhoQCCPvDByDBxk6UFgMwk3HmDJAWZmK0MEC1zOYBUYS0yM9ufmzwwMBOXn724YfNNr+2yfMxMzB++JiDW4vBnWPGCQkGyYYbzqUZNuf23TZsY2Zglpy5DY8WiQTjAwkGzIwbeBjMH+f23GYEamFj5sWjRX5G+meglnr7+T3sH5ste27bE9TCcCMH5LDDiQ1neAybGX7cTiSoxeBGTrFBgsHx5A1neAobextuJ7cxMzbj9QvQYZslf1RU2wIdtrHhx5/btvPbmw9++IjPYSiAsQ1MNhCrHgT+kKJ4FIyCUTAKRgoAAIycULIvWky8AAAAAElFTkSuQmCC","orcid":"","institution":"Yeungnam University","correspondingAuthor":true,"submittingAuthor":false,"prefix":"","firstName":"shakilaparveen","middleName":"","lastName":"asrafali","suffix":""}],"badges":[],"createdAt":"2022-03-09 09:19:49","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-1434024/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-1434024/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":19379171,"identity":"94a78f97-b768-411c-a9b1-e5657fbd0854","added_by":"auto","created_at":"2022-03-18 18:24:16","extension":"jpg","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":62736,"visible":true,"origin":"","legend":"\u003cp\u003eFT-IR spectrum of Bzo-BN\u003c/p\u003e","description":"","filename":"Fig1.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/21eb23e00f4a0149d4a3b2ea.jpg"},{"id":19379168,"identity":"4ae09556-f039-45b1-a315-293ff003aed4","added_by":"auto","created_at":"2022-03-18 18:24:16","extension":"jpg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":65777,"visible":true,"origin":"","legend":"\u003cp\u003e\t\u003csup\u003e1\u003c/sup\u003eH- and \u003csup\u003e13\u003c/sup\u003eC-NMR spectra of Bzo-BN\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Fig2.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/e8bc7bdd1c9affe67a819aa4.jpg"},{"id":19379144,"identity":"e6ad8c28-9de4-49e0-a7a1-8c5c6ca7801d","added_by":"auto","created_at":"2022-03-18 18:21:16","extension":"jpg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":55456,"visible":true,"origin":"","legend":"\u003cp\u003eDSC thermograms of (a) Bzo-BN/T0; (b) Bzo-BN/T1; (c) Bzo-BN/T3; (d) Bzo-BN/T5\u003c/p\u003e","description":"","filename":"Fig3.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/b2195b4b91fd482493665a94.jpg"},{"id":19379169,"identity":"717575b6-d09d-43ee-a7ac-04aeacda4b82","added_by":"auto","created_at":"2022-03-18 18:24:16","extension":"jpg","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":95462,"visible":true,"origin":"","legend":"\u003cp\u003eSEM images of (a) Pbz-BN/T0; (b) Pbz-BN/T1; (c) Pbz-BN/T3; (d) Pbz-BN/T5\u003c/p\u003e","description":"","filename":"Fig4.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/3e9d7d141aa1b38e55620a1e.jpg"},{"id":19379146,"identity":"5958e027-f76d-43ab-8eef-6bb0a92b6116","added_by":"auto","created_at":"2022-03-18 18:21:16","extension":"jpg","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":103117,"visible":true,"origin":"","legend":"\u003cp\u003eAFM images of (a) Pbz-BN/T0; (b) Pbz-BN/T1; (c) Pbz-BN/T3; (d) Pbz-BN/T5\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Fig5.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/256f07f4849358d071338cfe.jpg"},{"id":19379147,"identity":"f17c5de1-27ea-410a-892b-f54c8cb31634","added_by":"auto","created_at":"2022-03-18 18:21:16","extension":"jpg","order_by":6,"title":"Figure 6","display":"","copyAsset":false,"role":"figure","size":33319,"visible":true,"origin":"","legend":"\u003cp\u003e\tStatic WCA of (a) Pbz-BN/T0; (b) Pbz-BN/T1; (c) Pbz-BN/T3; (d) Pbz-BN/T5\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Fig6.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/a70f1a16e432923be30ebb8a.jpg"},{"id":19379148,"identity":"2333032a-7c62-405e-8c03-ba5e1db89551","added_by":"auto","created_at":"2022-03-18 18:21:16","extension":"jpg","order_by":7,"title":"Figure 7","display":"","copyAsset":false,"role":"figure","size":80157,"visible":true,"origin":"","legend":"\u003cp\u003eDMA analysis showing storage modulus [7A] and loss modulus [7B] (a) Pbz-BN/T0; (b) Pbz-BN/T1; (c) Pbz-BN/T3; (d) Pbz-BN/T5\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Fig7.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/b09f3d24407afbdb033b579d.jpg"},{"id":19379170,"identity":"e57693b7-2962-408c-bc1a-4daece6ae20b","added_by":"auto","created_at":"2022-03-18 18:24:16","extension":"jpg","order_by":8,"title":"Figure 8","display":"","copyAsset":false,"role":"figure","size":57501,"visible":true,"origin":"","legend":"\u003cp\u003e\tTGA thermograms of (a) Pbz-BN/T0; (b) Pbz-BN/T1; (c) Pbz-BN/T3; \u003c/p\u003e\u003cp\u003e\t(d) Pbz-BN/T5\u003c/p\u003e\u003cp\u003e\u003cbr\u003e\u003c/p\u003e","description":"","filename":"Fig8.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/405abf11a0f700dd9636afa2.jpg"},{"id":19379153,"identity":"bf43aeb5-e25c-46a3-b662-983c180692b4","added_by":"auto","created_at":"2022-03-18 18:21:17","extension":"jpg","order_by":9,"title":"Figure 9","display":"","copyAsset":false,"role":"figure","size":68376,"visible":true,"origin":"","legend":"\u003cp\u003eDielectric constant [9A] and dielectric loss [9B] of (a) Pbz-BN/T0; (b) Pbz-BP/T1; (c) Pbz-BN/T3; (d) Pbz-BN/T5\u003c/p\u003e","description":"","filename":"Fig9.jpg","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/c18fac2344e229fbd1192185.jpg"},{"id":19379172,"identity":"d0a56a29-fe85-45ec-b1dd-4f24fe92a356","added_by":"auto","created_at":"2022-03-18 18:24:20","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":904819,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/255787e2-0474-45a0-9d7d-d6c441b10702.pdf"},{"id":19379152,"identity":"7a189e75-7f94-4212-9950-49fa504971e6","added_by":"auto","created_at":"2022-03-18 18:21:16","extension":"docx","order_by":4,"title":"","display":"","copyAsset":false,"role":"supplement","size":914281,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementarydata.docx","url":"https://assets-eu.researchsquare.com/files/rs-1434024/v1/212d9e1de7fa2cd2c1e33c71.docx"}],"financialInterests":"","formattedTitle":"\u003cp\u003eDevelopment of Hybrid Titania/Polybenzoxazine Composite for Enhance Thermo-Mechanical, Flame Retardancy and Dielectric Properties\u003c/p\u003e","fulltext":[{"header":"Introduction","content":"\u003cp\u003ePolybenzoxazine (Pbz), as a new class of thermosetting phenolic resins has been developed to overcome the shortcomings of traditional phenolic resin, while keeping the advantages of cost effectiveness, heat resistance and flame retardancy. Benzoxazine based thermosets exhibit high glass transition temperature and high modulus even though they have relatively low crosslink densities owing to strong hydrogen bonding restricting segmental mobility and impeding network formation\u003csup\u003e\u003cspan additionalcitationids=\"CR2 CR3 CR4\" citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. In spite of these, Pbz is considered as a new class of low surface energy materials and exhibits a large number of interesting properties, such as near zero shrinkage during curing, high carbon content, low water absorption, high thermal stability, excellent electrical properties etc. Low surface energy is important for many practical applications in coatings, self-cleaning materials and biomaterials\u003csup\u003e\u003cspan additionalcitationids=\"CR7 CR8\" citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eSeveral studies have been conducted to improve the mechanical properties of polymers, such as strength, toughness and elastic modulus, among which the combination of nanoparticles (NPs) is one of the most current research topics. Since NPs are usually aggregated due to the strong van der Waals force, it is very difficult to achieve mono-dispersity in a resin matrix at the nanoscale. Agglomerated fillers not only suffers the mechanical properties of the cured matrix, but also act as initiation points of cracks and fractures, which even deteriorate the mechanical properties. In other words, one of the critical issues is to achieve a non-aggregated dispersion of the integrated NPs to impart the polymer matrix its remarkable mechanical, electrical and thermal properties. Their dispersion characteristics and interfacial adhesion can be improved by modifying the NP surface with suitable dispersants or polymer coating\u003csup\u003e\u003cspan additionalcitationids=\"CR10 CR11 CR12 CR13 CR14 CR15\" citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eModification of nano fillers with functional benzoxazine monomer (Bzo-BN) has proven to be a promising approach to prepare nanocomposites by exploiting high flexibility of benzoxazine molecular design by synthesizing titania/polybenzoxazine nanocomposites via thermal curing process. Transparent hybrid films were obtained, suggesting dispersion of nano sized titania particles in a polybenzoxazine matrix. Novel polymer composite with nano-TiO\u003csub\u003e2\u003c/sub\u003e content reinforced with polybenzoxazine were prepared. The adhesion between nano-TiO\u003csub\u003e2\u003c/sub\u003e and Pbz-BN was found to be strong, and the distribution of nano fillers was relatively uniform; a novel benzoxazine with benzonitrile functionalization (Bzo-BN) was prepared and blended with TiO\u003csub\u003e2\u003c/sub\u003e (with different ratios) leading to the formation of highly dispersible organic/inorganic polybenzoxazine/TiO\u003csub\u003e2\u003c/sub\u003e hybrid composites\u003csup\u003e\u003cspan additionalcitationids=\"CR18 CR19 CR20 CR21 CR22 CR23\" citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e\u003c/sup\u003e.\u003c/p\u003e \u003cp\u003eThe effect of dispersion of different wt% of TiO\u003csub\u003e2\u003c/sub\u003e particles in benzoxazine was investigated by analyzing their polymer properties, viz., mechanical, thermal, water resistance and dielectric properties. TiO\u003csub\u003e2\u003c/sub\u003e was used in this work as it has a linear coefficient of thermal expansion closer to that of the polymer matrix and other excellent properties, such as high strength and surface toughness and excellent wear resistance. Although several studies on the effect of various dispersants on the mechanical behavior of polybenzoxazine nanocomposites have been reported previously, no studies based on benzoxazine/TiO\u003csub\u003e2\u003c/sub\u003e matrices have been reported. Therefore, our preparation and evaluation procedure provides a good way to facilitate the dispersion of inorganic NPs with benzoxazine dispersants and to further improve the mechanical properties of benzoxazine/TiO\u003csub\u003e2\u003c/sub\u003e composites.\u003c/p\u003e "},{"header":"Experimental","content":"\u003cp\u003e\u003cstrong\u003eMaterials and methods\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe materials, instrumentation methods, synthesis of precursors, i.e., 4-(phenyl diazenyl) phenol [PAP] and 4,4\u0026rsquo; bis(4-aminophenoxy) benzonitrile [APBN] \u0026nbsp;and structure analysis of these precursors are given in the ESI.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSynthesis of bis(6-phenyl diazenyl-3-phenoxy-3,4-dihydro-2H-1,3-benzoxazinyl) benzonitrile [Bzo-BN]\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eTo start with, paraformaldehyde (1.8 g, 0.06 mol) was dissolved in DMSO (50 mL) at 100 ℃. To the dissolved solution, the synthesized diamine (APBN, 3.2 g, 0.01 mol) and the phenol (PAP, 3.9 g, 0.02 mol) were added in parts and the reaction mixture was further increased to 130 ℃. After completion of reaction, the reaction mixture was allowed to reach room temperature and the product precipitated in 1N NaOH solution. The collected precipitate was water washed to remove any un-reactants, filtered and dried at 60 ℃ to afford brown powder of Bzo-BN monomer [Scheme 1]. Yield: 82%\u003c/p\u003e\n\u003cp\u003eFT-IR (KBr, cm\u003csup\u003e-1\u003c/sup\u003e): 936 (stretching vibrations of the oxazine ring), \u0026nbsp; 1256 \u0026amp; 1045 (asymmetric and symmetric stretching vibrations of C-O-C), 1177 (stretching of C-N-C), 1340 (CH\u003csub\u003e2\u003c/sub\u003e wagging), 2246 ( -CN stretching vibrations), 1445 (trans N=N stretching vibrations); \u003csup\u003e1\u003c/sup\u003eH-NMR (CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): \u0026nbsp;5.4 (s, H\u003csub\u003ea\u003c/sub\u003e, 4H), 4.6 (s, H\u003csub\u003eb\u003c/sub\u003e, 4H) and 6.5\u0026ndash;8.0 (m, aromatic protons);\u003csup\u003e\u0026nbsp;13\u003c/sup\u003eC-NMR CDCl\u003csub\u003e3\u003c/sub\u003e, ppm): 79 (O-CH\u003csub\u003e2\u003c/sub\u003e-N), 50 (Ar-CH\u003csub\u003e2\u003c/sub\u003e-N), 115 (-CN), 94 (Ar (C)-CN) and 110\u0026ndash;155 (aromatic carbons).\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePreparation of Pbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003ePbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites with varying ratios of TiO\u003csub\u003e2\u003c/sub\u003e were prepared. Briefly, the synthesized Bzo monomer and TiO\u003csub\u003e2\u003c/sub\u003e (1 wt% of Bzo-BN) was mixed with THF and stirred well to form a homogeneous solution. This solution was then poured onto petridish, pretreated with dichlorodimethyl silane (for easy release of the cured film) and then cured maintaining the temperature at 250 ℃ for 3h. The cured films were then taken out with care. Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composite thus prepared was denoted as Pbz-BN/T1. Similarly, other ratios of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites were denoted as Pbz-BN/T0; Pbz-BN/T3 and Pbz-BN/T5, respectively with varying the weight ratio of TiO\u003csub\u003e2\u003c/sub\u003e.\u003c/p\u003e"},{"header":"Results And Discussions","content":"\u003cp\u003e\u003cstrong\u003eStructural analysis of benzoxazine monomer [Bzo-BN]\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe FT-IR spectra of the synthesized benzoxazine monomer [Bzo-BN] was shown in Figure 1. It can be seen from the figures that the benzoxazine ring is characterized by the absorption bands between 936 cm\u003csup\u003e-1\u003c/sup\u003e, due to the stretching vibrations of the oxazine ring. Moreover, the benzoxazine ring also gave its characteristic absorption band at 1219 cm\u003csup\u003e-1\u003c/sup\u003e, 1021 cm\u003csup\u003e-1\u003c/sup\u003e due to the asymmetric and symmetric stretching vibrations of the C-O-C bond, stretching vibrations of the C-N-C bond respectively\u003csup\u003e25\u003c/sup\u003e. The nitrile (-CN) group show their characteristic absorption bands at 2246 cm\u003csup\u003e-1\u003c/sup\u003e. Figure 2, illustrates the \u003csup\u003e1\u003c/sup\u003eH-NMR and \u003csup\u003e13\u003c/sup\u003eC-NMR spectra of the benzoxazine monomer Bzo-BN. The oxazine ring protons (H\u003csub\u003ea\u003c/sub\u003e, O-CH\u003csub\u003e2\u003c/sub\u003e-N and H\u003csub\u003eb\u003c/sub\u003e, Ar-CH\u003csub\u003e2\u003c/sub\u003e-N) show two singlets at 5.4 and 4.6 ppm, respectively\u003csup\u003e26-28\u003c/sup\u003e. The aromatic ring protons are located between 6.5 - 8.0 ppm. The \u003csup\u003e13\u003c/sup\u003eC-NMR spectrum shows the characteristic carbon resonances of Bzo-BN. The methylene carbons [O-CH\u003csub\u003e2\u003c/sub\u003e-N (C\u003csub\u003e1\u003c/sub\u003e) and Ar-CH\u003csub\u003e2\u003c/sub\u003e-N (C\u003csub\u003e2\u003c/sub\u003e)] of the oxazine ring resonate at 79 and 50 ppm, respectively. The carbon of the benzonitrile group (C\u003csub\u003e3\u003c/sub\u003e) resonates at 115 ppm. And the aromatic carbon attached to the benzonitrile group (C4) resonates at 94 ppm\u003csup\u003e29\u003c/sup\u003e. All other aromatic carbons resonate between 110 - 155 ppm, respectively.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003ePolymerization behavior of hybrids\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDSC of the hybrids was performed to study the polymerization behavior of benzoxazine monomer in presence of TiO\u003csub\u003e2\u003c/sub\u003e by monitoring the typical exothermic peak attributed to the ring opening polymerization of benzoxazine (Bzo-BN) and their hybrids (Bzo-BN/T0-T5). DSC showed that the neat benzoxazine monomer exhibits an exothermic curve with T\u003csub\u003eonset\u003c/sub\u003e at 224 ℃, T\u003csub\u003emax\u003c/sub\u003e at 243 ℃ and T\u003csub\u003efinal\u003c/sub\u003e at 256 ℃. In comparison, for the hybrids, the exothermic curve shows that T\u003csub\u003eonset\u003c/sub\u003e slightly shifted to lower temperature (218 ℃) and T\u003csub\u003emax\u003c/sub\u003e and T\u003csub\u003efinal\u003c/sub\u003e shifted to 251 and 262 ℃, respectively. This result indicates that the ring opening polymerization of benzoxazine monomer has been accelerated by the presence of nitrile group (act as a catalyst) and thus lowers its onset of curing temperature. The addition of TiO\u003csub\u003e2\u003c/sub\u003e particles into the Bzo monomer shifts the maximum and final curing temperature to higher value, which could be due to the trapped TiO\u003csub\u003e2\u003c/sub\u003e particles inside the monomer. Moreover, the \u0026Delta;H value of Bzo-BN/TiO\u003csub\u003e2\u003c/sub\u003e hybrids decreases with increasing TiO\u003csub\u003e2\u003c/sub\u003e content. This is due to the fact that with increased TiO\u003csub\u003e2\u003c/sub\u003e content, the Bzo content in the Bzo-BN/TiO\u003csub\u003e2\u003c/sub\u003e hybrid decreased obviously, thus reducing their enthalpy values. Similar exothermic curing behavior was observed for BA-a/inorganic nano fibers (30 wt%), where, the maximum curing temperature of neat BA-a (240 ℃) was shifted to 250 ℃ with incorporation of the inorganic materials\u003csup\u003e30,31\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 1\u0026nbsp;\u003c/strong\u003eData from DSC thermograms of Bzo-BN/TiO\u003csub\u003e2\u003c/sub\u003e hybrids\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"10.444874274661508%\"\u003e\n \u003cp\u003e\u003cstrong\u003eS.No.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.3752417794971%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"17.988394584139265%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTiO\u003csub\u003e2\u003c/sub\u003e ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.3752417794971%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT \u003csub\u003eonset\u0026nbsp;\u003c/sub\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.44100580270793%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT \u003csub\u003emax\u003c/sub\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.3752417794971%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT \u003csub\u003efinal\u0026nbsp;\u003c/sub\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"10.444874274661508%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" width=\"18.3752417794971%\"\u003e\n \u003cp\u003eBzo-BN/TiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"17.988394584139265%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.3752417794971%\"\u003e\n \u003cp\u003e224\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.44100580270793%\"\u003e\n \u003cp\u003e243\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.3752417794971%\"\u003e\n \u003cp\u003e256\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"12.796208530805687%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.03791469194313%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e223\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.14218009478673%\"\u003e\n \u003cp\u003e245\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e258\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"12.796208530805687%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.03791469194313%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e220\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.14218009478673%\"\u003e\n \u003cp\u003e248\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e261\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"12.796208530805687%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.03791469194313%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e218\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.14218009478673%\"\u003e\n \u003cp\u003e251\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.511848341232227%\"\u003e\n \u003cp\u003e262\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMorphology of PBz-BP/TiO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003ecomposites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eFigure 4 shows the SEM micrographs of PBz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites. The smooth surface of pure polybenzoxazine is clearly visible from the figure. As the titanium content increases (from 1 to 5% by weight), the surface of the composites loses its smoothness and becomes rough. It also shows the formation of homogeneous hybrid material and fine dispersion of titanium particles. The small size of the titanium particles may be responsible for the transparency of the hybrid materials\u003csup\u003e32\u003c/sup\u003e. \u0026nbsp;As the TiO\u003csub\u003e2\u003c/sub\u003e content increases to 5% loading, few voids or gaps appear on the surface of the composites. AFM images (Fig. 5) of polybenzoxazine and their composites show that the size of the nodules formed by the Pbz-TiO\u003csub\u003e2\u003c/sub\u003e particles is uniform and has a uniform distribution, as seen in the SEM images. The surface roughness of polybenzoxazine-silica hybrids was calculated from AFM measurements using the following equation\u003csup\u003e33\u003c/sup\u003e,\u003c/p\u003e\n\u003cp\u003eR\u003csub\u003et\u003c/sub\u003e = R\u003csub\u003ep\u003c/sub\u003e + R\u003csub\u003ev\u003c/sub\u003e\u003c/p\u003e\n\u003cp\u003eWhere R\u003csub\u003et\u003c/sub\u003e is the total roughness of the measured sample, R\u003csub\u003ep\u003c/sub\u003e is the maximum peak height of the profile, and R\u003csub\u003ev\u003c/sub\u003e is the maximum valley depth of the profile. The total roughness was found to be 8, 83, 109, and 128 nm for Pbz-BP:T0, Pbz-BP:T1, Pbz-BP:T3, and Pbz-BP:T5, respectively. The roughness value increases with increasing titanium content from 1 to 5 wt%, which is consistent with the AFM images.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eSurface Properties of the polybenzoxazine-titania hybrids\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAs is known, superhydrophobic surfaces can be prepared by combining low surface area and free energy materials with rough structures. In this case, Pbzo-BN with a network of hydrogen bonds and nitrile structures were used as a low surface area and free energy material\u003csup\u003e34\u003c/sup\u003e. The addition of TiO\u003csub\u003e2\u003c/sub\u003e NPs was able to form rough structures. Figure 6 shows the WCAs of neat polybenzoxazine and polybenzoxazine-titania hybrid [Pbz-BP:T1, Pbz-BP:T3 and Pbz-BP:T5] coatings with different mass ratios of TiO\u003csub\u003e2\u003c/sub\u003e NPs. The pure Pbz coating showed hydrophobicity with a WCA of 87\u0026deg;. With the increase of the additional amount of TiO\u003csub\u003e2\u003c/sub\u003e NPs, the hydrophobicity of the Pbz/TiO\u003csub\u003e2\u003c/sub\u003e also increased significantly with a linear increase in WCA from 87 to 146 \u0026deg;C. The hydrophobicity of polybenzoxazine was improved by incorporating TiO\u003csub\u003e2\u003c/sub\u003e nanoparticles even at low concentrations (e.g. 5 wt% TiO\u003csub\u003e2\u003c/sub\u003e). The increased hydrophobicity of the [Pbz-BP:T5] hybrid is attributed to the air trapped in the voids of the rough surface and preventing water from entering the nanoparticles, leading to an increase in the contact angle with water\u003csup\u003e35\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDynamic mechanical Properties of titanium-modified polybenzoxazine hybrids\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe dynamic mechanical properties of the hybrid materials in comparison to neat polybenzoxazine were examined. Fig. 7 shows the storage modulus (E\u0026prime;) and loss modulus (E\u0026Prime;) as a function of temperature. The storage modulus of the neat Pbz drops slowly up to 125 \u0026deg;C, after which there is a sharp drop with a glass transition temperature (T\u003csub\u003eg\u003c/sub\u003e) of 147 \u0026deg;C obtained from the maximum of loss modulus. The storage moduli of the composites in the glassy state increase with the inclusion of titanium particles, and rise more on further increasing the content of titanium in the hybrids\u003csup\u003e36-38\u003c/sup\u003e. This behavior indicates that the dispersed titanium nanoparticles are effective to reinforce polybenzoxazine matrix. The drastic improvement of the storage modulus of polybenzoxazine by hybridization with small amount of titanium nanoparticles (5%) can be attributed to the reinforcing role of the titanium nanoparticles and the increase of the polymerization degree of polybenzoxazine via their nitrile group on the ring opening polymerization similar to the role of silica, clay and other inorganic nanomaterials on polybenzoxazines nanocomposites as previously reported\u003csup\u003e37,39\u003c/sup\u003e. Also, the hybrids show higher T\u003csub\u003eg\u003c/sub\u003e than the neat resin. The T\u003csub\u003eg\u003c/sub\u003e of pure polybenzoxazine was found to be 147 \u0026deg;C; but for the composites, the T\u003csub\u003eg\u003c/sub\u003e increased with increasing nano filler content (T\u003csub\u003eg\u003c/sub\u003e of Pbz-BP/T5 is 164 \u0026deg;C). The hard and rigid inorganic regions create an obstacle to the movements of random chain segments in the matrix. This restricted mobility of the segmental molecular chains results with an increased T\u003csub\u003eg\u003c/sub\u003e values. A similar increase in T\u003csub\u003eg\u003c/sub\u003e values is observed in PBA-a composites with other inorganic nanofibers, ranging between 185 and 193 \u0026deg;C\u003csup\u003e40-43\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 2\u0026nbsp;\u003c/strong\u003eDMA\u0026nbsp;data of Pbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"15.650741350906095%\"\u003e\n \u003cp\u003e\u003cstrong\u003eS.No.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"15.650741350906095%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"15.321252059308073%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTiO\u003csub\u003e2\u003c/sub\u003e ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"3\" width=\"53.37726523887974%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp;DMA\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"35.38461538461539%\"\u003e\n \u003cp\u003e\u003cstrong\u003eStorage modulus\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"35.38461538461539%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003eg\u0026nbsp;\u003c/sub\u003e(\u003csup\u003eo\u003c/sup\u003eC)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"29.23076923076923%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCLD\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003e*10\u003csup\u003e5\u003c/sup\u003e mol/m\u003csup\u003e3\u003c/sup\u003e\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"15.625%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" width=\"15.625%\"\u003e\n \u003cp\u003ePBz-BN/TiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.296052631578947%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.914473684210527%\"\u003e\n \u003cp\u003e2.81\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.914473684210527%\"\u003e\n \u003cp\u003e147\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"15.625%\"\u003e\n \u003cp\u003e3.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.51851851851852%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.128654970760234%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e3.15\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e151\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.51851851851852%\"\u003e\n \u003cp\u003e4.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.51851851851852%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.128654970760234%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e3.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e157\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.51851851851852%\"\u003e\n \u003cp\u003e4.2\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"18.51851851851852%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.128654970760234%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e3.26\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"22.417153996101366%\"\u003e\n \u003cp\u003e164\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"18.51851851851852%\"\u003e\n \u003cp\u003e4.3\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCross-link density of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe cross-link density (CLD), \u0026gamma;\u003csub\u003ec\u003c/sub\u003e is the number of network chain molecules per unit volume of the cured polymer. The cross-linking density of highly cross-linked thermoset materials can be determined by modulus measurements using the modulus constitutive equation given below\u003csup\u003e44\u003c/sup\u003e,\u003c/p\u003e\n\u003cp\u003e\u0026gamma;\u003csub\u003ec\u003c/sub\u003e = ɛ\u0026apos;/3RT\u003c/p\u003e\n\u003cp\u003eWhere,\u003c/p\u003e\n\u003cp\u003eɛ\u0026apos; = storage tensile modulus (from DMA)\u003c/p\u003e\n\u003cp\u003eT = temperature in K corresponding to the value of the storage modulus\u003c/p\u003e\n\u003cp\u003eR = gas constant\u003c/p\u003e\n\u003cp\u003eTable 2 shows the interconnect density of the Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites. The crosslinking density of the pure polymer, i.e. Pbz-BN/T0, was found to be 3.7*10\u003csup\u003e-5\u003c/sup\u003e mol m\u003csup\u003e-3\u003c/sup\u003e, while the crosslinking density of the composite, i.e. Pbz-BN/T5, was found to be 4.3*10\u003csup\u003e-5\u003c/sup\u003e mol m\u003csup\u003e-3\u003c/sup\u003e. It can be seen that the crosslinking density obviously increases with the increase in the nanoparticle content in the composites. The main reason is that the nanoparticles behave as natural cross-linkers by forming intermolecular hydrogen bonds between the hydroxyl groups of the nanoparticles and the -OH, \u0026nbsp;-CN, of the polybenzoxazine(s), thus limiting their molecular motion\u003csup\u003e45,46\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eThermal stability of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe thermal stability of the hybrids was studied by thermogravimetric analysis to investigate the effect of dispersed titanium particles on the thermal stability of the polybenzoxazine matrix. Figure 8 shows the TGA profiles under nitrogen atmosphere of pure Pbz and the composites containing various percentages of titanium. For pure Pbz, T\u003csub\u003e5\u003c/sub\u003e and T\u003csub\u003e10\u003c/sub\u003e are 326 \u0026amp; 354 \u0026deg;C with a carbon yield of 42.6%. The incorporation of titanium particles in the Pbz matrix led to an increase in thermal stability. For example, the carbon yield increased from 42.6 to46.4, 51.2 and 53.7% with the addition of 0, 1, 3 and 5 wt% titania, suggesting that the dispersed titanium particles in the matrix act as a thermal insulator to protect the Pbz matrix. Also, the composites also contain nitrile group, by which the thermal stability showed a greater improvement. This could be attributed to the maximized adhesion between the organic (Pbz) and inorganic (titanium) sites, which further protect the organic matrix with thermal insulation\u003csup\u003e47-49\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 3\u0026nbsp;\u003c/strong\u003eTGA\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003edata of Pbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd valign=\"top\" width=\"9.591474245115453%\"\u003e\n \u003cp\u003e\u003cstrong\u003eS.No.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.518650088809945%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"16.163410301953817%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTiO\u003csub\u003e2\u003c/sub\u003e ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.900532859680284%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003ei\u0026nbsp;\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cstrong\u003e℃\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.966252220248668%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e5\u0026nbsp;\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cstrong\u003e℃\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"12.966252220248668%\"\u003e\n \u003cp\u003e\u003cstrong\u003eT\u003csub\u003e10\u0026nbsp;\u003c/sub\u003e\u003c/strong\u003e\u003cstrong\u003e(\u003c/strong\u003e\u003cstrong\u003e℃\u003c/strong\u003e\u003cstrong\u003e)\u003c/strong\u003e\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.946714031971581%\"\u003e\n \u003cp\u003e\u003cstrong\u003eCY\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.946714031971581%\"\u003e\n \u003cp\u003e\u003cstrong\u003eLOI\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"9.591474245115453%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" width=\"16.518650088809945%\"\u003e\n \u003cp\u003ePBz-BN/TiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"16.163410301953817%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"11.900532859680284%\"\u003e\n \u003cp\u003e286\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.966252220248668%\"\u003e\n \u003cp\u003e326\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"12.966252220248668%\"\u003e\n \u003cp\u003e354\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.946714031971581%\"\u003e\n \u003cp\u003e42.6\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"9.946714031971581%\"\u003e\n \u003cp\u003e34.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"11.48936170212766%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.361702127659573%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.25531914893617%\"\u003e\n \u003cp\u003e296\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e351\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e374\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e46.4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e36.1\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"11.48936170212766%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.361702127659573%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.25531914893617%\"\u003e\n \u003cp\u003e308\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e364\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e386\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e51.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e38.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"11.48936170212766%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"19.361702127659573%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"14.25531914893617%\"\u003e\n \u003cp\u003e313\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e378\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"15.53191489361702%\"\u003e\n \u003cp\u003e403\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e53.7\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd valign=\"top\" width=\"11.914893617021276%\"\u003e\n \u003cp\u003e39.0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFlame retardancy of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThe flammability resistance of pure Pbz and Pbz-TiO\u003csub\u003e2\u003c/sub\u003e composites is explained as a function of the limiting oxygen index (LOI) value. One way to calculate the LOI is by TGA analysis, knowing their corresponding carbon yield values. van Krevelen and Hofytzer used the equation\u003csup\u003e50\u003c/sup\u003e given below to calculate the LOI,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLOI=17.5+0.4*CY\u003c/p\u003e\n\u003cp\u003eWhere,\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eLOI is the oxygen limit index,\u003c/p\u003e\n\u003cp\u003eCY is the carbon yield (from TGA data).\u003c/p\u003e\n\u003cp\u003eThe value of LOI for the pure Pbz-BN polymer was 34.5. And their composites showed LOI values of 36.1, 38.0 and 39.0 for Pbz-BN/T1, Pbz-BN/T3 and Pbz-BN/T5, respectively (Table 3). It could be observed that the LOI value of polybenzoxazine and their composites were higher than the threshold value (26). This clearly indicates that the incorporation of TiO\u003csub\u003e2\u003c/sub\u003e nanoparticles in the Pbz system results in thermosets with good self-extinguishing and flame retardant properties.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eDielectric properties of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eDielectric materials can be used to store electrical energy in the form of charge separation when the electron distributions around their constituent atoms or molecules are polarized by an external electric field. The dielectric constant is directly related to the polarizability of the material and is therefore highly dependent on its chemical structure. Figure 9 shows the values of the dielectric constant and the dielectric loss of Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites. The values of dielectric constant and dielectric loss were found to be in the range of 3.2 - 2.9 and 0.94 - 0.78, respectively for Pbz-BN/TiO\u003csub\u003e2\u0026nbsp;\u003c/sub\u003ecomposites, respectively (Table 4). Composites differ from micro composites in three aspects: they contain small amounts of fillers, the filler particles have sizes in the order of nanometers, and the interface between the filler and the polymer is large. Nanoparticles reduce the movement of the polymer chain by physical bonding\u003csup\u003e51\u003c/sup\u003e. The mobility of the charge carriers, also decreased with particle loading, suggesting that the nanoparticles disperse the carriers by reducing their mobility, leading to a decrease in permeability with increasing frequency\u003csup\u003e52\u003c/sup\u003e.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eTable 4\u0026nbsp;\u003c/strong\u003eDielectric\u003cstrong\u003e\u0026nbsp;\u003c/strong\u003edata of Pbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites\u003c/p\u003e\n\u003ctable border=\"0\" cellpadding=\"0\" cellspacing=\"0\" width=\"0\"\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"20.518358531317496%\"\u003e\n \u003cp\u003e\u003cstrong\u003eS.No.\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"20.518358531317496%\"\u003e\n \u003cp\u003e\u003cstrong\u003eSample\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"2\" valign=\"top\" width=\"20.086393088552917%\"\u003e\n \u003cp\u003e\u003cstrong\u003eTiO\u003csub\u003e2\u003c/sub\u003e ratio\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd colspan=\"2\" width=\"38.8768898488121%\"\u003e\n \u003cp\u003e\u003cstrong\u003e\u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; \u0026nbsp; Dieletric\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"52.77777777777778%\"\u003e\n \u003cp\u003e\u003cstrong\u003eConstant\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"47.22222222222222%\"\u003e\n \u003cp\u003e\u003cstrong\u003eLoss\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"20.518358531317496%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd rowspan=\"4\" width=\"20.518358531317496%\"\u003e\n \u003cp\u003ePBz-BN/TiO\u003csub\u003e2\u003c/sub\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.086393088552917%\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"20.518358531317496%\"\u003e\n \u003cp\u003e3.2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"18.3585313174946%\"\u003e\n \u003cp\u003e0.94\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e2\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.27173913043478%\"\u003e\n \u003cp\u003e1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e3.1\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.097826086956523%\"\u003e\n \u003cp\u003e0.93\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.27173913043478%\"\u003e\n \u003cp\u003e3\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e3.0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.097826086956523%\"\u003e\n \u003cp\u003e0.87\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e4\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.27173913043478%\"\u003e\n \u003cp\u003e5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"25.815217391304348%\"\u003e\n \u003cp\u003e2.9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd width=\"23.097826086956523%\"\u003e\n \u003cp\u003e0.78\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n\u003c/table\u003e"},{"header":"Conclusion","content":"\u003cp\u003eIn this study, a novel benzoxazine monomer (Bzo-BN) containing benzonitrile moiety was synthesized using a simple Mannich condensation reaction. Titania particles (with varying contents) were directly mixed with the Bzo monomer and thermally cured undergoing self-polymerization to produce Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites. The curing behavior of the Bzo monomer and their hybrids with TiO2 has been much accelerated by the presence of benzonitrile group. A sharp increase in the contact angle for the composite Pbz-BN/T5 (146\u0026deg;) was observed even with a very less amount of titania loading (~\u0026thinsp;5 wt%). In spite of this, a drastic improvement in thermal i.e., T5\u0026thinsp;=\u0026thinsp;378 ℃; T10\u0026thinsp;=\u0026thinsp;403 ℃, mechanical i.e., E' = 3.26 GPa and dielectric i.e., ɛ' = 2.9 was obtained for Pbz-BN/T5. These improvements are due to the difference in surface energies between Pbz and inorganic fillers that generated surfaces with various roughness an caused important ameliorations in the thermo-mechanic and dielectric properties of the neat Pbz resin. This type of conventional processing enables the use of low-cost fabrication processes and provides flexibility for designing superhydrophobic surfaces that have enough potential to be utilized in a wide range of practical applications.\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003eC.H. Lu, Y.C. Su, C.F. Wang, C.F. Huang, Y.C. Sheen, F.C. Chang, Thermal properties and surface energy characteristics of interpenetrating polyacrylate and polybenzoxazine networks. Polymer \u003cb\u003e49\u003c/b\u003e, 4852\u0026ndash;4860 (2008)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eC.F. Wang, Y.C. Su, S.W. Kuo, C.F. Huang, Y.C. Sheen, F.C. Chang, Low-surface-free-energy materials based on polybenzoxazines. Angew Chem. Int. Ed. \u003cb\u003e45\u003c/b\u003e, 2248\u0026ndash;2251 (2006)\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eL. Qu, Z. 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Zhou, Synthesis and surface properties of low surface free energy silane-functional polybenzoxazine films. Langmuir \u003cb\u003e29\u003c/b\u003e, 411\u0026ndash;416 (2013)\u003c/span\u003e\u003c/li\u003e\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":"polybenzoxazines, benzonitrile, TiO2 fillers, composites, superhydrophobic","lastPublishedDoi":"10.21203/rs.3.rs-1434024/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-1434024/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003ePolybenzoxazines (Pbzs) are recently developed class of thermosetting polymeric materials possessing low surface free energy with non-fluorine or non-silicon content. In the present study, a new type of Pbz-BN/TiO\u003csub\u003e2\u003c/sub\u003e composites were fabricated using benzoxazine monomer [bis(6-phenyl diazenyl-3-phenoxy-3,4-dihydro-2H-1,3-benzoxazinyl) benzonitrile] and inorganic TiO\u003csub\u003e2\u003c/sub\u003e fillers by a simple and inexpensive process. Thermal curing method was found to be effective for preparing superhydrophobic surfaces combining low surface energy and surface roughness. The presence of benzonitrile group in the benzoxazine monomer paves way for accelerating the curing of the benzoxazine monomer as shown by the DSC analysis. The as-prepared Pbz/TiO\u003csub\u003e2\u003c/sub\u003e surfaces containing 5 wt% of TiO\u003csub\u003e2\u003c/sub\u003e generated a superhydrophobic surface exhibiting static water contact angle (SWCA) of 146\u0026deg;. In addition to it, the effect of inorganic fillers on the thermal, mechanical and dielectric properties of the Pbz/TiO\u003csub\u003e2\u003c/sub\u003e composites was investigated in detail.\u003c/p\u003e","manuscriptTitle":"Development of Hybrid Titania/Polybenzoxazine Composite for Enhance Thermo-Mechanical, Flame Retardancy and Dielectric Properties","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2022-03-18 18:21:14","doi":"10.21203/rs.3.rs-1434024/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":"3322be7e-0373-4012-8d83-f8f65f96dadb","owner":[],"postedDate":"March 18th, 2022","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2022-03-18T18:21:16+00:00","versionOfRecord":[],"versionCreatedAt":"2022-03-18 18:21:14","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-1434024","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-1434024","identity":"rs-1434024","version":["v1"]},"buildId":"WrCJVZZCHTDjtuVLN7oU0","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}