Effect of 3‐aminopropyltriethoxysilane on properties of poly(butyl acrylate‐co‐maleic anhydride)/silica hybrid materials

The transparent poly(butyl acrylate‐co‐maleic anhydride)/silica [P(BA‐co‐MAn)/SiO₂] has been successfully prepared from butyl acrylate‐maleic anhydride copolymer P(BA‐co‐MAn) and tetraethoxysilane (TEOS) in the presence of 3‐aminopropyltriethoxysilane (APTES) by an in situ sol–gel process. Triethoxysilyl group can be readily incorporated into P(BA‐co‐MAn) as pendant side chains by the aminolysis of maleic anhydride unit of copolymer with APTES, and then organic polymer/silica hybrid materials with covalent bonds between two phases can be formed via the hydrolytic polycondensation of triethoxysilyl group‐functionalized polymer with TEOS. It was found that the amount of APTES could dramatically affect the gel time of sol–gel system, the sol fraction of resultant hybrid materials, and the thermal properties of hybrid materials obtained. The decomposition temperature of hybrid materials and the final residual weight of thermogravimetry of hybrid both increase with the increasing of APTES. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that the morphology of hybrid materials prepared in the presence of APTES was a co‐continual phase structure. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 419–424, 1999     

Study of poly(methyl methacrylate–maleic anhydride)/silica hybrid materials

Poly(methyl methacrylate–maleic anhydride) [P(MMA–MAn)] with active groups, anhydrides, was synthesized by radical copolymerization. Using P(MMA–MAn) as a basic polymer, the P(MMA–MAn)/SiO₂ hybrid materials were obtained by a sol–gel process in different ways. The structures of the materials were characterized by IR spectra, and their properties were studied by thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and dynamic analysis (DA). The results show that the hybrids prepared in different ways have different properties, and the contents of SiO₂ also have influence on the properties of the hybrids. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 379–383, 2000     

New epoxy/silica‐titania hybrid materials prepared by the sol–gel process

A new type of inorganic‐polymer hybrid materials of epoxy/silica‐titania had been prepared by incorporating grafted epoxy, which had been synthesized by epoxy and tetraethoxysilane (TEOS), with highly reactive TEOS and tetrabutyltitanate (TBT) by using the in situ sol–gel process. The grafted epoxy was confirmed by Fourier transform infrared spectroscopy (FT‐IR) and ¹H‐NMR spectroscopic technique. Results of FT‐IR spectroscopy and atomic force microscopy (AFM) demonstrated that epoxy chains have been covalently bonded to the surface of the SiO₂‐TiO₂ particles. The particles size of SiO₂‐TiO₂ are about 20–50 nm, as characterized by AFM. The experimental results showed that the glass‐transition temperatures and the modulus of the modified systems were higher than that of the unmodified system, and the impact strength was enhanced by two to three times compared with that of the neat epoxy. The morphological structure of impact fracture surface and the surface of the hybrid materials were observed by scanning electron microscopy and AFM, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1075–1081, 2006     

Stabilized dispersions of titania nanoparticles via a sol–gel process and applications in UV‐curable hybrid systems

Organic–inorganic hybrid UV‐curable coatings were synthesized through blending UV‐curable components and stabilized titania sol prepared via a sol–gel process of tetrabutyl titanate (TBT) with three different stabilizers, acetylacetone (Acac), isopropyl tri(dioctyl)pyrophosphato titanate coupling agent (TTPO) and a polymerizable organic phosphoric acid (MAP). The size and the dispersion of titania particle in the UV‐cured organic matrix were dominated by the properties of these stabilizers. A cured hybrid film with titania particle size around 20 nm was obtained when TTPO was utilized as protection agent for the sol. It is interesting that the hardness and flexibility of the photocured hybrid films were improved simultaneously, in contrast to results with neat organic UV‐curable formulations. Copyright © 2006 Society of Chemical Industry     

Organic base‐catalyzed sol–gel route to prepare PMMA–silica hybrid materials

A series of sol–gel‐derived organic–inorganic hybrid materials that comprise organic poly(methyl methacrylate) (PMMA) and inorganic silica (SiO₂) was successfully prepared using aniline as an organic base catalyst to catalyze the sol–gel reactions of tetraethylorthosilicate (TEOS). Aniline was adopted not only as a catalyst but also as a dispersing agent during the preparation of the hybrid materials. The as‐prepared hybrid materials were then characterized using transmission electron microscopy, SEM/energy dispersive X‐ray spectroscopy and Fourier transform infrared spectroscopy. The characteristic temperatures (including T_d and T_g) of the hybrid materials slightly exceeded those of neat PMMA, as revealed from thermogravimetric analysis and differential scanning calorimetry evaluations. Studies of the protection against corrosion demonstrated that the hybrid coatings all improved the protection performance on cold‐rolled steel coupons relative to that of neat PMMA coatings, according to measurements of electrochemical corrosion parameters. Additionally, incorporating silica particles into the polymer may effectively reduce the gas permeability of the polymer membrane. Reducing the size of silica particles (at the same silica feeding) further improved the gas barrier property. Optical clarity studies indicated that introducing silica particles into the PMMA matrix may slightly reduce the optical clarity of the films/membranes, as determined by UV‐visible transmission spectroscopy. The contact angle of H₂O of the hybrid films increased with the amount of aniline. Copyright © 2006 Society of Chemical Industry Society of Chemical Industry     

Synthesis and characterization of nanocomposite of polyimide–silica hybrid from nonaqueous sol–gel process

Polyimide–silica (PI–SiO₂) hybrids with a nanostructure was obtained using the nonaqueous sol–gel process by polycondensation of phenyltriethoxysilane in a polyamic acid solution. Self‐catalyzed hydrolysis of phenyl‐substituted akoxysilane and modification on the polyimide structure are applied and result in highly compatible PI–SiO₂ hybrids. Transparent PI–SiO₂ with a high silica content of about 45% was thus obtained. The prepared PI–SiO₂ films were characterized by infrared spectrometry, ²⁹Si‐NMR, thermogravimetric analysis, differential scanning calorimetry, and scanning electron microscopy. These characterizations showed the silica influence on the properties of the hybrid. The thermal expansion coefficient of the PI–SiO₂ and the temperature correlation were also established for probing the potential for application. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1609–1618, 2000     

Role of silane coupling agents for performance improvement of poly(vinyl acetate)/tetraethyl orthosilicate hybrid composites prepared by a sol–gel process

Silica based poly(vinyl acetate)/inorganic hybrid composites were prepared via a sol–gel process under acidic conditions. Because the phase behaviour of the hybrids is greatly affected by weak interactions such as hydrogen bonding between organic polymer and inorganic network, two types of silane coupling agent (vinyl trimethoxysilane and 3‐(trimethoxysilyl)propyl methacrylate) were used to introduce specific interactions and to control phase behaviour in the interface between polymer and silica. The interfacial interactions between polymer and inorganic segment in the presence of silane have been investigated by Fourier transform infrared spectroscopy. Thermogravimetric analysis shows that the thermal stability of organic components in the hybrids is enhanced by addition of silane coupling agents. Scanning electron micrographs reveal that silica particles are homogeneously dispersed in the organic matrix as a result of the specific interactions. © 2001 Society of Chemical Industry     

Preparation and properties of organosoluble polyimide/silica hybrid materials by sol–gel process

Organosoluble polyimide/silica hybrid materials were prepared using the sol–gel process. The organosoluble polyimide was based on pyromellitic anhydride (PMDA) and 4,4′‐diamino‐3,3′‐dimethyldiphenylmethane (MMDA). The silica particle size in the hybrid is increased from 100–200 nm for the hybrid containing 5 wt % silica to 1–2 µm for the hybrid containing 20 wt % silica. The strength and the toughness of the hybrids are improved simultaneously when the silica content is below 10 wt %. As the silica content is increased, the glass transition temperature (T_g) of the hybrids is increased slightly. The thermal stability of the hybrids is improved obviously and their coefficients of thermal expansion are reduced. The hybrids are soluble in strong polar aprotic organic solvents when the silica content is below 5 wt %. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2977–2984, 1999     

Syntheses and optical properties of hybrid materials containing azobenzene groups via sol–gel process for reversible optical storage

We focused on the synthesis and optical properties of new organic–inorganic hybrid materials containing azobenzene groups for rewritable optical recording media. Hybrid material (SGUR19‐n's) design has the structure of azobenzene group with urethane bonds in the silica network. The structures of the synthesized monomers and precursors were confirmed by FTIR and ¹H NMR spectrophotometer. Also, we reported on the effects of the direction of the polarized beam, the intensity of the induced beam, and the structures of SGUR19‐n's materials on the diffraction efficiency of SGUR19‐n's films. It was revealed that SGUR19‐n's films prepared by the sol–gel process have adequate writing–erasing–rewriting properties when used as a reversible optical storage material. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4811–4818, 2006     

Preparation and characterization of epoxy resin modified with alkoxysilane‐ functionalized poly(urethane‐imide) by the sol–gel process

The sol–gel process has been frequently employed for preparation of high performance silica/polymer composites. In this paper, novel sol–gel precursor triethoxysilane‐terminated poly(urethane‐imide) (PUI‐Si), combining the advantages of polyurethane (PU) and polyimide, was synthesized and characterized. Then PUI‐Si was incorporated into the epoxy resin matrix to prepare a series of EP/PUI‐Si organic‐inorganic hybrids through an in situ sol–gel process and crosslinking reactions. The thermal stability of EP/PUI‐Si hybrids was evaluated by thermogravimetric analysis and the results show that the PUI‐Si could significantly improve the thermal properties of epoxy resin. The initial decomposition temperature of composites with 50 wt% PUI‐Si reached 347.1 °C, 157.3 °C higher than that of neat epoxy resin. Furthermore, the tensile strength and breaking elongation can also be clearly improved by adding a suitable amount of PUI‐Si. Similarly, the water contact angle increased to 97.4° with 70 wt% PUI‐Si, showing a hydrophobic surface. The morphology was investigated by transmission electron microscopy and the results reveal that the silica particles are smaller than 20 nm and have a strong interaction with the epoxy resin matrix, resulting in the above‐mentioned high performance properties. Copyright © 2011 Society of Chemical Industry     

Preparation and characterization of polyimide/Al2O3 hybrid films by sol–gel process

A sol–gel process has been developed to prepare polyimide (PI)/Al₂O₃ hybrid films with different contents of Al₂O₃ based on pyromellitic dianhydride (PMDA) and 4,4′‐oxydianiline (ODA) as monomers. FESEM and TEM images indicated that Al₂O₃ particles are relatively well dispersed in the polyimide matrix after ultrasonic treatment of the sol from aluminum isopropoxide and thermal imidization of the gel film. The dimensional stability, thermal stability, mechanical properties of hybrid PI films were improved obviously by an addition of adequate Al₂O₃ content, whereas, dielectric property and the elongation at break decreased with the increase of Al₂O₃ content. Surprisingly, the corona‐resistance property of hybrid film was improved greatly with increasing Al₂O₃ content within certain range as compared with pure PI film. Especially, the hybrid film with 15 wt % of Al₂O₃ content exhibited obviously enhanced corona‐resistance property, which was explained by the formation of compact Al₂O₃ network in hybrid film. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of novel saponified guar‐graft‐poly(acrylonitrile)/silica nanocomposite materials

The combination of carbohydrates with silicon‐based ceramic materials offers attractive means of production for high performance materials. Present article describes the synthesis of novel nanocomposites out of SiO₂ and saponified guar‐graft‐poly(acrylonitrile) (SG). Tetraethoxysilane was used as the precursor for silica and growth of SiO₂ phase was allowed concurrently in the presence of SG. The material so obtained was thermally treated at 80°C, 160°C, 500°C, and 900°C to study the effect of thermal curing on its properties. During the curing process, silanol surface groups of silica globules reacted to create the reinforced SiO₂‐SG substance. It was observed that at 900°C, the SiO₂ phase crystallized out in tetragonal shape (similar to Cristobalite form of silica) in presence of SG. The chemical, structural and textural characteristics of the composites were determined by FTIR, XRD, TGA‐DTA, SEM and BET studies. The materials were also evaluated as efficient Zn²⁺ metal binder. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 536–544, 2007     

Synthesis and characterization of novel ultraviolet‐curing polyurethane acrylate/epoxy acrylate/SiO2 hybrid materials via sol–gel reaction

A series of ultraviolet‐curable hybrid materials was first synthesized here by sol–gel process based on tetraethoxysilane (TEOS) and polyurethane acrylate/epoxy acrylate resin. The functional groups in the hybrid materials were investigated by infrared spectroscopy (IR) analysis. The crystallinity of the hybrid materials and polymer resin was examined by X‐ray diffraction. Then, nearly uniform dispersion of SiO₂ particles with the diameters ?100 nm were revealed by field emission scanning electron micrographs. The surface morphology was scanned by atomic force microscope. And, thermal stability was measured by thermogravimetric analysis for hybrid materials produced from different mass ratio of TEOS to polymer. The results show that the hybrid material from the mass ratio of TEOS to polymer of 0.4 : 1 performed desirable optimal thermal stability and uniform microstructure which is suitable for optical fiber coating in high temperature application. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and water absorbency of a novel poly(acrylate‐co‐acrylamide)/vermiculite superabsorbent composite

A novel poly(acrylate‐co‐acrylamide)/expanded vermiculite (EVMT) superabsorbent composite was synthesized by aqueous solution polymerization method. The water absorbency of the superabsorbent composite still reaches 850 g/g when 50 wt % EVMT is added, which is significant in decreasing the production cost of the superabsorbent composites. By controlling the molar ratio of acrylic acid monomer and acrylamide monomer, and neutralization degree of acrylic acid, the hydrophilic groups on the composite can be adjusted, and it is found that the collaborative absorbent effect of ? CONH₂, ? COOK, and ? COOH groups is superior to that of single ? CONH₂, ? COOK, or ? COOH group. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 735–739, 2007     

Preparation and properties of rigid‐rod polyimide/silica hybrid materials by sol–gel process

Polyimide (PI) materials with a low coefficient of thermal expansion (CTE) while still retaining high strength and toughness are desirable in various applications. In this study a sol–gel process was used to incorporate silica into homopolyimides and copolyimides with highly rigid structures in an attempt to pursue this aim. A number of highly rigid monomers were used, including pyromellitic dianhydride (PMDA), p‐phenylene diamine (PPA), m‐phenylene diamine (MPA), benzidine, 2,4‐diaminotoluene, and o‐toluidine. No homopolyimide flexible films were obtained. However, it was possible to obtain flexible films from the copolyimides. Therefore, a copolyimide based on PPA, MPA, and PMDA (PPA/MPA = 2/1 mol) was then chosen as the matrix to prepare the PI/silica hybrids. Flexible films were obtained when the silica content was below 40 wt %. The hybrid films possessed low in‐plane CTEs ranging from 14.9 to 31.1 ppm with the decrease of the silica content. The copolyimide film was strengthened and toughened with the introduction of an appropriate amount of silica. The thermal stability and the Young's modulus of the hybrid films increased with the increase of the silica content. The silica particle size was assessed by scanning electron microscopy and was about 100 nm for the hybrids containing 10 and 20 wt % silica and 200–500 nm for the hybrids containing 30 and 40 wt % silica. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 794–800, 2001     

Preparation and degradability of poly(lactic acid)–poly(ethylene glycol)–poly(lactic acid)/SiO2 hybrid material

Poly(lactic acid)–poly(ethylene glycol)–poly(lactic acid) (PLA‐PEG‐PLA)/SiO₂ hybrid material is prepared by sol–gel method using tetraethoxysilane (TEOS) and PLA‐PEG‐PLA as raw material. From Fourier transform infrared spectroscopy (FTIR) and X‐ray photoelectron spectroscopy (XPS) spectra, the hydroxyl groups of the silica sol derived from partially hydrolysis of TEOS and the unhydrolyzed ethoxy groups of TEOS can react with PLA‐PEG‐PLA. Differential scanning calorimetry (DSC) curves imply that the glass transition temperature (T_g) of PLA‐PEG‐PLA/SiO₂ hybrid material is higher than that of PLA‐PEG‐PLA and increases with the increase of silica content. X‐ray diffraction (XRD) analysis results show that PLA‐PEG‐PLA and PLA‐PEG‐PLA/SiO₂ hybrid material are both amorphous. Field scanning electron microscope (FSEM) photographs show that when PLA‐PEG‐PLA/SiO₂ hybrid material has been degraded for 12 weeks in normal saline at 37°C, a three‐dimensional porous scaffold is obtained, which is available for cell growth and metabolism. Moreover, the hydroxyl (? OH) groups on SiO₂ of PLA‐PEG‐PLA/SiO₂ hybrid material could buffer the acidity resulted from the degradation of PLA, which is beneficial to proliferation of cell in tissue repairing. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis,characterization, and thermal stability of PMMA/SiO2/TiO2 tertiary nanocomposites via non‐hydrolytic sol–gel method

In this study, we use PMMA, tetraethoxysilane and titanium ethoxide to prepare tertiary nanocomposites via non‐hydrolytic sol–gel method. Boron trifluoride monoethylamine was used as catalyst. Silica and titanium dioxide are incorporated into nanocomposites to improve the thermal stability. Thermogravimetric analysis was used for rapid evaluation of the thermal stability of different materials. The integral procedural decomposition temperature has been correlated the volatile parts of polymeric materials and used for estimating the inherent thermal stability of polymeric materials. The thermal stability of hybrids increased with the contents of inorganic components. The inorganic components can improve the thermal stability of PMMA copolymer. Two methods have been used to study the degradation of hybrid during thermal analysis. These investigated methods are Kissenger', Ozawa's methods to classify the thermal stability of nanocomposites. The activation energies of hybrids were higher than that of the copolymer. From the results, silica and titania will enhance the thermal stability of PMMA. We use the solubility test to check the network structure of nanocomposites. The results show the residues of composites after extraction increase with the increasing of inorganic contents. We can conclude that the composites possess network structure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Surlyn®/silicate hybrid materials. I. Polymer in situ sol–gel process and structure characterization

We report the creation of a new organic/inorganic hybrid material that results from sol–gel reactions for tetraethylorthosilicate (TEOS) within poly[ethylene‐co‐methacrylic acid], as well as within a Zn⁺² partially neutralized form of this copolymer (Surlyn®). FTIR and ²⁹Si solid‐state NMR spectroscopic probes yield information regarding molecular connectivity within the in situ grown silicate structures. FTIR analyses of Surlyn® matrix bands suggest that strong molecular level interactions between the organic and inorganic phases are not present, although there is other evidence that these phases are mechanically coupled on a larger dimensional scale. The ²⁹Si solid‐state NMR analyses indicate mainly Q₃ and Q₄ coordination states about the SiO₄ substructures, regardless of silicate content, which is in general agreement with the interpretation of the FTIR results that show incomplete condensation. Environmental scanning electron microscopy and energy dispersive X‐ray analysis results reinforce the conclusion that a significant silicate component is incorporated deep within TEOS‐treated films. Differential scanning calorimetry studies of Surlyn®‐Zn⁺²/silicate hybrids suggest that silicate incorporation essentially does not disrupt crystallinity. Thermogravimetric analyses show practically no change in the degradation onset temperature, which is consistent with organic/inorganic phase separation. The general conclusion is that a silicate phase can indeed be incorporated within this acid copolymer, as well as its Zn⁺² ionomeric form, via in situ sol–gel processes. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 2832–2844, 2000     

Phase‐separation prevention and performance improvement of poly(vinyl acetate)/TEOS hybrid using modified sol‐gel process

The formation of covalent bonds between silanols in copolymer and those in silica prevents organic–inorganic phase separation. Two series of hybrid composite materials, poly(vinyl acetate‐co‐vinyl trimethoxysilane)/TEOS and poly[vinyl acetate‐co‐3‐(trimethoxysilyl)propyl methacrylate]/TEOS, were fabricated using a modified sol‐gel process. The hybrids were transparent. Two kinds of silane coupling agents, vinyl trimethoxysilane (VTS) and 3‐(trimethoxysilyl)propyl methacrylate (γ‐MPS), were used to prevent macrophase separation through formation of covalent bonds. Thermal analysis showed that γ‐MPS was more effective than VTS for the formation of covalent bonds. Enhancement of thermal stability of the hybrids was investigated by thermogravimetric analysis. Photomicrographs of scanning electron microscopy and images of atomic force microscopy indicated that inorganic silica particles were homogeneously dispersed in less than 50 nm in organic matrix. The morphological properties of hybrids were strongly dependent on the organic–inorganic composition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2310–2318, 2001     

聚甘油酯化改性PMVE/MAH的合成及吸水性能研究

以甲基乙烯基醚/马来酸酐共聚物(PMVE/MAH)与十聚甘油为原料,采用溶剂接枝法,制得聚甘油酯化改性PMVE/MAH。采用红外光谱和热分析仪对酯化产物进行了结构表征。研究了反应酯化率对产物性能的影响,考察了产物的热稳定性、保水性能、耐电解质性和重复吸水性能。结果表明,酯化率12.5%的共聚物吸水性最强,pH=7时吸水倍率为353 g/g,最适宜酸碱性条件为pH=8,此时酯化改性共聚物吸水倍率可达719 g/g,耐盐性良好,50℃环境温度下16 h仍有67.2%的保水率。