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     

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     

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     

PU/SiO2杂化材料的制备与表征

用溶胶-凝胶法制备了一系列聚氨酯(PU)／SiO2杂化材料,通过扫描电子显微镜和傅里叶变换红外光谱考察了杂化材料的相容性、微观相互作用以及介电性能。实验发现．水和催化剂的用量控制得当可得到分散均匀的杂化材料;在10μm厚的聚对苯二甲酸乙二酯(PET)薄膜上涂有2μm厚的PU／SiO2杂化材料,体系的介电常数较纯PET薄膜提高1倍多。     

Preparation and adsorption performances of novel negatively charged hybrid materials

A series of novel negatively charged hybrid materials were prepared via sol–gel process and a subsequent epoxide ring‐opening reaction. The coupling reaction was conducted between 3‐glycidoxypropyltrimethoxysilane (GPTMS) and tetraethoxysilane (TEOS), which was confirmed by FTIR spectra. TGA, and DrTGA analyses showed that their thermal stabilities were higher and the optimal molar ratio of GPTMS and TEOS was equal to 1 : 1. The ion‐exchange capacities (IECs) exhibited that they were related to the amount of anionic groups in the hybrid materials, indicating that the negatively charged properties of the hybrid materials could be artificially controlled via the adjustment of silica in these charged hybrid materials. The adsorption properties for Pb²⁺ and Cu²⁺ ions revealed that these hybrid materials were able to absorb heavy metal ions, suggesting that they have potential applications in the separation and recovery of environmentally hazardous substances. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

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 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     

Preparation and phenol captivating properties of polyvinylpyrrolidone‐montmorillonite hybrid materials

Montmorillonite minerals were modified in two distinct steps in order to remove hydroxlated toxicants from the aqueous environment. At first, the montmorillonite minerals were acrylated with the silylating agent γ‐methcaryloxypropyl trimethoxysilane to give a product denoted as TAY‐10. In the second step these materials readily reacted with vinylpyrrolidone to form copolymers covalently bonded to the clay. All hybrid materials were characterized by FTIR spectroscopy, thermogravimetry, X‐ray diffractometry, SEM, and differential thermal analysis. The original montmorillonite structure was maintained for the copolymer modified surfaces. Different loadings of polyvinylpyrrolidone (PVP) were examined to arrive at the optimal conditions for the removal of toxicants from the aqueous environment. The presence of the PVP enhanced the adsorption capacity of the clay toward phenolic compounds from solution as evidenced by the retention percent that was as high as 98.9%. These results demonstrated the feasibility of utilizing a PVP modified clay as a thermally recyclable adsorbent for environmental pollutants. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 512–519, 2001     

Effect of chemical interaction on morphology and mechanical properties of CPI‐OH/SiO2 hybrid films with coupling agent

A novel hybrid film composed of copolyimide with hydroxyl group, silica and γ‐glycidyloxypropyltrimethoxysilane (CPI‐OH/SiO₂/GOTMS) was prepared by the sol–gel process based on hydrolyzed tetraethoxysilane (TEOS) under acidic condition. GOTMS, as the coupling agent, and hydroxyl group in PI chain were used to improve the compatibility between the PI and SiO₂. The components, morphologies, and mechanical properties of the hybrids were investigated by FTIR, UV–vis, SEM, stress–strain tests, and DMA. The results showed that SiO₂ particle size significantly decreased, fractured cross sections of hybrid were rougher, and the surfaces of spherical SiO₂ particles were more widely covered by PI component. The tensile mechanical properties of hybrids increased when adding GOTMS. The critical points of maximum tensile strength and elongation at break move from 11 to 16 wt % SiO₂ content. DMA results showed that the storage moduli of hybrids with GOTMS, when above 260°C, were obviously higher than those without GOTMS; the tan δ transition temperature of hybrid films went up from 317 to 337°C. It suggests that chemical interaction between CPI‐OH and SiO₂ is formed and the PI molecular mobility is restricted by the chemical interaction. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3530–3538, 2007     

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     

Highly crosslinked nanocomposites of aromatic dicyanates/SiO2 via the sol–gel method

Highly crosslinked nanocomposites of bisphenol A dicyanate (BADCy) containing silica clusters were successfully prepared via the sol–gel process. The silica clusters were generated from various metal alkoxide precursors, including methyltrimethoxysilane (TMOS), 3‐glycidoxypropyltrimethoxysilane (GPOS), and 2‐(3,4‐epoxycyclohexyl) ethyltrimethoxysilane (ECOS). The metal alkoxide precursors GPOS and ECOS were, in turn, used as coupling agents. Three kinds of systems involving BADCy/TMOS, BADCy/coupling agent, and BADCy/TMOS/coupling agent were individually prepared and thoroughly investigated using various methods. Each kind of system was of a particular characterization and morphology and had distinct physical and dielectric properties. Isolated silica clusters on a nanoscale were homogenously distributed in the highly crosslinked BADCy/TMOS hybrid system. The characterization of BADCy/TMOS nanocomposites showed improved physical properties, when compared with the neat BADCy network. The particle sizes can be controlled by adding different amounts of TMOS and are slightly increased (in the range of 50–105 nm) with increasing TMOS content. On the other hand, in the highly crosslinked BADCy/coupling agent hybrid system, the silica clusters were tethered to the BADCy matrix by the coupling agent. An oxazoline linkage was detected during the reaction of cyanate groups in BADCy with the epoxide groups in the coupling agent. These nanocomposites exhibited weakened mechanical properties but are of a smaller and more homogenous particle size in the range of 30–50 nm, irrespective of the silica content. Finally, the BADCy/TMOS/coupling agent system was successfully designed to combine the advantages of the two systems mentioned above. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1356–1366, 2007     

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     

Synthesis and characterization of poly(methyl acrylate‐co‐itaconic anhydride)/TiO2 hybrid materials via sol–gel process

In the presence of 3‐aminopropyltriethoxysilane (APTES), the transparent and yellowish poly(methyl acrylate‐co‐itaconic anhydride)/TiO₂ [P(MA‐co‐Itn)/TiO₂] hybrid materials were prepared from the copolymer of methyl acrylate and itaconic anhydride [P(MA‐co‐Itn)] and tetrabutyl titanate (TBT) via a sol–gel process. At first, the triethoxysilane groups were incorporated into the copolymer P(MA‐co‐Itn) as pendant side chains by the aminolytic reaction between the itaconic anhydride units of the copolymer and the amino group of 3‐aminopropyltriethoxysilane (APTES), and then the covalent bonds between the organic and inorganic phases were introduced by the hydrolysis and polycondensation of the triethoxysilane groups on the copolymer with TBT. FTIR analysis proved the existence of the covalent bonds. The influences of APTES on glass transition and morphology of the hybrid materials was studied by differential scanning calorimetry, scanning electron microscope, and atomic force microscope. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1763–1768, 2000     

Novel organic–inorganic chemical hybrid fillers for dental composite materials

A series of new polymethacrylate–silica chemical hybrid dental fillers has been prepared by the sol–gel reactions of poly[methyl methacrylate-co-3-(trimethoxysilyl) propyl methacrylate] or poly[3-(trimethoxysilyl)propyl methacrylate] with tetraethyl orthosilicate at various compositions. In these hybrid fillers, the polymethacrylate chains are uniformly distributed in and covalently bonded to the silica networks at molecular level without macroscopic organic–inorganic phase separation. The contact angle and surface tension parameters indicate that the hybrid fillers have better wetting properties with the 2,2-bis(p-2-hydroxy-3-methacryloxypropoxyphenyl)propane/triethyleneglycol dimethacrylate resin and stronger interfacial bonding with the polymer matrix than pure silica fillers. The compressive testing results demonstrate that the dental composites prepared with the hybrid fillers tend to have enhanced mechanical properties in comparison to those with the silane-treated fused silica and the pure sol-gel silica fillers at the same silica content. Scanning electron micrographic study reveals that upon compressive tests the dental composites with the hybrid fillers have fewer failures at the filler–matrix interface than those with pure silica fillers. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 1689–1699, 1998     

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     

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     

Effect of pigmentation on polyurethane/polysiloxane hybrid coatings

Rutile TiO₂ was formulated into polyurethane/polysiloxane hybrid coatings in order to investigate the influence of pigmentation on the inorganic phase of the hybrid coatings. Two urethanes were prepared from the isocyanurate of hexane diisocyanate (HDI), alkoxysilane modified HDI, and tetraethyl orthosilicate (TEOS) oligomers, with oligoesters derived from either cyclohexane diacids (CHDA) and 2‐butyl‐2‐ethyl‐1,3‐propanediol (BEPD) or adipic acid (AA), isophthalic acid (IPA), 1,6‐hexanediol (HD), and trimethylol propane (TMP). The oligoesters were spectroscopically characterized using GPC, FT‐IR, and NMR. Chemical interaction between the TiO₂ and the sol–gel precursor was investigated using solid‐state ²⁹Si NMR and XPS. The morphology, mechanical, viscoelastic, thermal properties of the pigmented coatings are evaluated as a function of pigmentation volume concentration (PVC). Using AFM and SEM, the pigment was observed to be well dispersed in the polymer binder. The thermal stability, the tensile modulus, and strength of the coatings were enhanced with increasing PVC, whereas the pull‐off adhesion and flexibility (elongation‐at‐break) were reduced with increasing PVC. Finally, the pigmented coatings were evaluated by electrochemical impedance spectroscopy (EIS) and the results showed that 10 wt % of the pigment improved the corrosion resistance of the entire coating system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42947.     

Synthesis and characterization of flame retarding UV‐curable organic–inorganic hybrid coatings

UV‐curable, organic–inorganic hybrid materials were synthesized via sol–gel reactions for tetraethylorthosilicate, and methacryloxypropyl trimethoxysilane in the presence of the acrylated phenylphosphine oxide resin (APPO) and a bisphenol‐A‐based epoxy acrylate resin. The sol–gel precursor content in the hybrid coatings was varied from 0 to 30 wt %. The adhesion, flexibility, and hardness of the coatings were characterized. The influences of the amounts of inorganic component incorporated into the coatings were studied. Results from the mechanical measurements show that the properties of hybrid coatings improve with the increase in sol–gel precursor content. In addition, thermal properties of the hybrids were studied by thermogravimetric analysis in air atmosphere. The char yield of pure organic coating was 32% and that of 30 wt % silicate containing hybrid coating was 30% at 500°C in air atmosphere. This result demonstrates the pronounced effect of APPO on the flame retardance of coatings. Gas chromatography/mass spectrometry analyses showed that the initial weight loss obtained in thermogravimetric analysis is due to the degradation products of the photoinitator and the reactive diluent. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1906–1914, 2006     

Synthetic preparations and physical and electrical properties of main chain type thermotropic liquid crystalline polyimide/SiO2 nanocomposites

Two kinds of monomers, 1,3‐bis[4‐(4′‐amino‐Phenoxy)cumyl]benzene (BACB) and pyromellitic dianhydride were used to synthesize the Liquid Crystalline Polyamic acid—a precursor (LCPAA) of Liquid Crystalline Polyimide (LCPi). The nanohybrid films were successfully prepared by the sol–gel reaction. Tetraethoxysilane (TEOS) (99%)–ethanol (99.8%) solution was added to LCPAA solution. The hybrid films were made by the hydrolysis–polycondensation of TEOS–ethanol in the LCPAA solution. When water and the solvent were removed completely, the hybrid films were obtained. The functional group and chemical structure were characterized by FTIR. We employed a number of instruments to understand whether the nano‐SiO₂ particle was introduced into the polymer matrix and enhanced the thermal properties and mechanical strength. The liquid crystalline phase of the LCPi and LCPi/SiO₂ hybrid films was observed by POM. TGA and DSC were used to test the thermal properties. The crystallization and liquid crystal phase analyses were carried out by XRD. The elemental analysis was employed to measure the 1,3‐bis[4‐(4′‐nitrophenoxy)cumyl)]benzene and BACB monomers. Besides, the cross section at morphology of the materials was observed with an FESEM. The electrical properties of hybrid films were measured by the high resistance analysis and dielectric constant analysis. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1688–1704, 2006     

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