Preparation,characterization, and properties of novolac‐type phenolic/SiO2 hybrid organic–inorganic nanocomposite materials by sol–gel method

This article describes the preparation of novolac‐type phenolic resin/silica hybrid organic–inorganic nanocomposite, with a sol–gel process. The coupling agent was used to improve the interface between the organic and inorganic phases. The effect of the structure of the nanocomposite on its physical and chemical properties is discussed. The coupling agent reacts with the resin to form covalent bonds. The structure of the modified hybrid nanocomposites was identified with a Fourier transform infrared spectroscope. The silica network was characterized by nuclear magnetic resonance imaging (²⁹Si NMR). Results revealed that Q₄ (tetrasubstituted) and T₃ (trisubstituted) are the dominant microstructures. The size of the silica in the phenolic resin was characterized with a scanning electron microscope. The size of the particles of inorganic silica in the modified system was less than 100 nm. The nanocomposite exhibited good transparency. Moreover, the thermal and mechanical properties exhibited significant improvement. The modified hybrid composite exhibited favorable thermal properties. The temperature at which a weight loss of 5% occurred increased from 281 to 350 °C. The flexural strength increased by 6–30%. The limiting oxygen index of the nanocomposite reached 37, and the Underwriters Laboratory test was 94V‐0. Consequently, these materials possess excellent flame‐retardant properties. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 905–913, 2003     

Preparation and characterization of poly(phthalazinone ether ketone)/SiO<Subscript>2</Subscript> hybrid composite thin films with low friction coefficient

Organic–inorganic poly(phthalazinone ether ketone) (PPEK)/SiO₂ hybrid composite thin films were prepared by the dip-coating method on pre-cleaned glass substrates. The covalent bonds between organic and inorganic phases were introduced by an in-situ O-acylation reaction of isocyanatopropyltriethoxysilane (ICPTES) with the borohydride-reduced PPEK forming a polymer bearing triethoxysilyl groups. Theses groups were subsequently hydrolyzed with tetraethoxysilane (TEOS) and allowed to form a network via a sol–gel process. The polymer hybrid composite exhibited good thermal stability and a higher glass transition temperature as compared with the pure resin. Atomic force microscope, water contact angle measurement and scanning electron microscope were used to characterize the polymer hybrid thin films. The tribological experiment showed that the films have very low friction coefficient (about 0.1) and good anti-wear properties, without failure even after sliding for 18,000 s under modest loads. The improved tribological properties of the modified substrate were attributed to good adherence of PPEK/SiO₂ hybrid films on the substrate and synergy of both PPEK matrix and silica particles.     

Synthesis and characterization of UV‐curable phosphorus containing hybrid materials prepared by sol–gel technique

In this study, a series of ultraviolet (UV)‐curable organic–inorganic hybrid coating materials containing phosphorus were prepared by sol–gel approach from acrylate end‐capped urethane resin, acrylated phenyl phosphine oxide oligomer (APPO), and inorganic precursors. TEOS and MAPTMS were used to obtain the silica network and Ti:acac complex was employed for the formation of the titania network in the hybrid coating systems. Coating performance of the hybrid coating materials applied on aluminum substrates was determined by the analysis techniques, such as hardness, gloss, impact strength, cross‐cut adhesion, taber abrasion resistance, which were accepted by international organization. Also, stress–strain test of the hybrids was carried out on the free films. These measurements showed that all the properties of the hybrids were enhanced effectively by gradual increase in sol–gel precursors and APPO oligomer content. The thermal behavior of the hybrid coatings was investigated by thermogravimetric analysis (TGA) analysis. The flame retardancy of the hybrid materials was examined by the limiting oxygen index (LOI); the LOI values of pure organic coating (BF) increased from 31 to 44 for the hybrid materials containing phosphorus (BF‐P:40/Si:10). The data from thermal analysis and LOI showed that the hybrid coating materials containing phosphorus have higher thermal stability and flame resistance properties than the organic polymer. Besides that, it was found that the double bond conversion values for the hybrid mixtures were adequate in order to form an organic matrix. The polycondensation reactions of TEOS and MAPTMS compounds were also investigated by ²⁹Si‐NMR spectroscopy. SEM studies of the hybrid coatings showed that silica/titania particles were homogenously dispersed through the organic matrix. In addition, it was determined that the hybrid material containing phosphorus and silica showed fibrillar structure. Copyright © 2009 John Wiley & Sons, Ltd.     

Coordination bonding assembly and photophysical properties of Europium organic/inorganic/polymeric hybrid materials

Ternary organic/inorganic/polymeric hybrid material PVP-Eu-(DBM-Si)₃ (DBM = dibenzoylmethane; PVP = poly(4-vinylpyridine)) have been synthesized through the coordination bonds. The precursor DBM-Si is obtained by the modification of DBM molecule with a cross-linking reagent TEPIC (3-(triethoxysilyl)-propyl isocyanate), which is used to form the inorganic Si–O–Si networks with TEOS (tetraethoxysilane) after a hydrolysis and polycondensation process. PVP, which is obtained through the polymerization reaction using 4-vinylpyridine as the monomer in the presence of BPO (benzoyl peroxide), is used to form the organic polymeric C–C chains. For comparison, the binary organic/inorganic hybrid material Eu-(DBM-Si)₃ was also synthesized simultaneously. FT-IR (Fourier-transform infrared spectra), UV (ultraviolet absorption spectra), UV-DR (ultraviolet–visible diffuse reflection absorption spectra), SEM (scanning electron micrograph), PL (photoluminescence spectroscopy) and LDT (luminescence decay time) measurements are used to investigate the physical properties of the obtained hybrid materials. The results reveal that the ternary hybrids presents more regular morphology, higher red/orange ratio, stronger luminescent intensity, higher ⁵D₀ luminescence quantum efficiency and longer lifetime than the binary one, suggesting the property of the overall hybrid system is improved with the introduction of the organic polymer PVP.     

A facile and controllable synthesis of dual‐crosslinked elastomers based on linear bifunctional polydimethylsiloxane oligomers

Dual‐crosslinked supramolecular elastomers with the hybrid network consisting of hydrogen bonds and covalent bonds combine the reversibility of hydrogen bond and mechanical properties of covalent crosslinking network. In this article, isocyanate mixture is used as curing agent to prepare dual‐crosslinked elastomer based on bifunctional polydimethylsiloxane under mild condition. This method can effectively build up a hybrid network with the designed structure. A series of elastomers with same hydrogen bond density and variable covalent crosslinking degree are obtained. Swelling measurements and ¹H‐NMR spectra confirm the feasibility and controllability of curing method, the increasing of bifunctional isocyanate give rise to higher covalent crosslinking degree, improving the solvent resistance. The studies on viscoelastic property show that the introduction of an irreversible covalent crosslinking network stabilize the hybrid network, restrain the chain movement. The mechanical and self‐healing property studies reveal that the covalent crosslink significantly reinforce the whole network, while the reparable strength seems to mainly depend on the hydrogen bond density. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3760–3768     

Reaction kinetics and network characterization of UV-curing polyester acrylate inorganic/organic hybrids

Polyester acrylate inorganic/organic hybrids were prepared using a sol-gel precursor, coupling agent, and reactive diluent. The hybrids were cured via a UV-free radical initiator. Design of experiments (DOE) was utilized to investigate reaction kinetics and complex variable interactions. The effects of the silicate groups on the free radical photo-curing reaction kinetics were investigated utilizing a time-resolved Fourier transform infrared (FT-IR) spectroscopy and a differential scanning calorimeter equipped with a photocalorimetric accessory (photo-DSC). Microgel and inorganic network formation during the UV-initiated free radical crosslinking reactions was suggested to describe the complex gel-point behavior. It was proposed that the formation of the inorganic silicate groups retarded the organic crosslinking reactions. The UV-cured inorganic/organic hybrid films exhibited more homogeneous film morphology compared to the organic counterparts. In the hybrid films, a core-shell like inorganic/organic particle morphology was observed. The UV-crosslinked organic phase forms the core, whereas, the inorganic silicate forms the surrounding shell.     

Hybrid inorganic/organic interpenetrating polymer networks based on zeolite 13x and polystyrene

A hybrid inorganic/organic interpenetrating polymer network (IPN) of a three-dimensional network structure zeolite crystal (13X, powder) and crosslinked or linear polystyrene (PS) was prepared and characterized by differential scanning calorimetry (DSC), solid-state¹³C-NMR, and scanning electron microscopy (SEM). The size and shape of the crystalline zeolite particles were revealed on SEM micrographs in both the pure zeolite and the IPNs. Solubility tests and the results of DSC with solid-state ¹³C-NMR confirm that some organic PS chains are incorporated within the internal three-dimensional channels of the zeolite particles. We speculate that the internal PS chains may adopt an extended “one-dimensional” conformation and exhibit no bulk polymer glass transition. These novel hybrid inorganic/organic IPNs are a new kind of IPN structure. © 1995 John Wiley & Sons, Inc.     

Multifunctional hybrid nanopapers based on bacterial cellulose and sol–gel synthesized titanium/vanadium oxide nanoparticles

The hybrid inorganic/organic nanopapers based on bacterial cellulose and different type of sol–gel synthesized nanoparticles are fabricated. A simple, rapid, low-cost pathway based on a diffusion step of sol–gel nanoparticles into swollen bacterial cellulose membrane via orbital incubator is developed. This alternative pathway allows to keeping intact the 3D network of the bacterial cellulose membrane while sol–gel nanoparticles are formed in situ and anchored on the nanofibers surface. Titanium, vanadium oxide nanoparticles and a mixture of both are used to functionalize bacterial cellulose membrane. Fabricated hybrid inorganic/organic nanopapers are characterized by thermogravimetric analysis, X-ray diffraction spectroscopy, scanning electron microscopy, energy dispersive X-ray spectroscopy, MTS mechanical testing, UV–vis spectroscopy, colorimeter and semiconductor analyzer. Synthesized photochromic hybrid nanopapers modified with vanadium and titanium oxide nanoparticles can find potential application as sensitive displays, biosensors and other optical devices.     

Preparation of poly(methyl acrylate‐co‐itaconic anhydride)/SiO2 hybrid materials via the sol–gel process—The effect of the coupling agent,inorganic content,and nature of the catalyst

Transparent poly(methyl acrylate‐co‐itaconic anhydride)/SiO₂ hybrid materials were prepared from methyl acrylate‐itaconic anhydride copolymer and tetraethoxysilane (TEOS) with the coupling agent (3‐aminopropyl)triethoxysilane (APTES) via a sol–gel process. The covalent bonds between the organic and inorganic phases were introduced by the in situ aminolysis of the itaconic anhydride units with APTES forming a copolymer bearing a triethoxysilyl group. These groups subsequently were hydrolyzed with TEOS and allowed to form a network. These reactions were monitored by Fourier transform infrared analysis. The amount of APTES had a dramatic influence on the gel time and sol fraction. The effect of APTES, the inorganic content, and the nature of the catalyst on the thermal properties and morphology of the hybrid materials were studied by differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy, and atomic force microscopy. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 321–328, 2000     

无机/有机杂化IPN的合成与表征

随着互穿聚合物网络(IPN)的发展,出现了无机/有机杂化IPN,调整两组分或多组分互穿程度控制材料的结构、形态与性能,可使材料具有较宽的适用范围.此类材料具有高模量、高韧性,易成型加工.     

Synthesis, characterization and thermal properties of novel PMDA-PAPD/silica hybrid network polymers

Novel PMDA-PAPD/silica hybrid polymers were synthesized by the sol-gel process. Fourier transform infrared spectroscopy and ²⁹Si nuclear magnetic resonance spectroscopy were used to characterize the structure of the hybrids, (condensed siloxane bonds designated as Q¹, Q², Q³, Q⁴, wth 3-aminopropyltriethoxysilane having mono-, di-, tri-, tetra-substituted siloxane bonds is designated as T¹, T² and T³). The results revealed that Q³, Q⁴ and T³ are the major microstructure elements in forming a network structure. The surface morphology, particle size, crystallinity and the thermal stability of the hybrids were investigated using Scanning electron microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). SEM and TEM revealed that the hybrids were nanocomposites. The XRD indicated that covalent bonding (Si-O-Si) between the organic and inorganic components enhanced miscibility. DSC and TGA results showed that these hybrid materials had excellent thermal stability. The heat capacities of some materials were reported for the temperature range 273 K and 363 K as no thermal anomaly was found in this temperature range.     

Rare-earth (Eu, Tb) hybrids through amide bridge: Chemically bonded self-assembly and photophysical properties

This work focuses on the construction of a series of chemically bonded rare-earth/inorganic/organic hybrid materials (TCH-Si-Ln, TCH-Si-Ln-Phen and TCH-Si-Ln-Bipy: Phen = 1,10-phenanthroline, Bipy = 2,2′-bipyridyl) using TCH-Si as an organic bridge molecule that can both coordinate to rare-earth ions (Eu³⁺ and Tb³⁺) and form an inorganic Si-O-Si network with tetraethoxysilane (TEOS) after cohydrolysis and copolycondensation through a sol-gel process. All of these hybrid materials exhibit homogeneous microstructures and morphologies, suggesting the occurrence of self-assembly of the inorganic network and organic chain. Measurements of the photoluminescent properties of these materials show that the ternary europium systems present stronger luminescent intensities than the binary hybrids, indicating that the introduction of the second ligands can sensitize the luminescence emission of the europium hybrid systems. However, in the terbium systems, this phenomenon was not observed.     

Imide-siloxane block copolymer/silica hybrid membranes: preparation, characterization and gas separation properties

Imide-siloxane block copolymer/silica hybrid membranes with covalent bonds were prepared via sol–gel reaction. The structural informations of these hybrid membranes were obtained by using Fourier transform-infrared spectrometry (FT-IR), ²⁹Si nuclear magnetic resonance (²⁹Si NMR), XPS and thermogravimetric analysis (TGA). The gas separation properties of the hybrid membranes were also investigated in terms of organosiloxane (PDMS) or silica content at various temperatures. In the hybrids, the addition of PDMS phase increased the permeabilities of gases such as He, CO₂, O₂, and N₂, indicating that the gas transport occurred mainly through rubbery organic matrix. Meanwhile, the PDMS phase contributed the decreased gas selectivities to nitrogen but the reduction in selectivities was very small in comparison with other siloxane containing polymeric membranes. This might be due to the restriction of chain mobility by the existence of inorganic component such as silica network in the hybrids. Additionally, the increase of silica content in these hybrid membranes considerably retarded the falling-off of gas selectivity at elevated temperature. The increase of silica content in hybrid membranes resulted in well-formed silica networks and hence these inorganic components restricted the plasticization of organic matrix by the thermal segmental motion of organic components, leading to preventing the large decrease of the gas selectivity.     

甲基丙烯酸(3-三甲氧基硅)丙酯-马来酸二丁基锡共聚物/二氧化硅杂化材料的制备

甲基丙烯酸（３ 三甲氧基硅）丙酯 马来酸二丁基锡共聚物／二氧化硅杂化材料的制备周文董建华丘坤元（北京大学化学与分子工程学院高分子科学与工程系，１００８７１北京）ＷｅｉＹｅｎ（危岩）（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒｙ，Ｄｒｅｘｅｌ...     

Preparation and properties of poly(styrene-co-maleic anhydride)/silica hybrid materials by the in situ sol–gel process

Poly(styrene-co-maleic anhydride)/silica hybrid material has been successfully prepared from styrene–maleic anhydride copolymer and tetraethoxysilane (TEOS) in the presence of a coupling agent (3-aminopropyl)triethoxysilane (APTES) by an in situ sol–gel process. It was observed that the gel time of sol–gel solution was dramatically influenced by the amount of APTES. The hybrid material exhibits optical transparency almost as good as both silica gel and the copolymer. The covalent bonds between organic and inorganic phases were introduced by the aminolysis reaction of the amino group with maleic anhydride units of copolymer to form a copolymer bearing trimethoxysilyl groups, which undergo hydrolytic polycondensation with TEOS. The differential scanning calorimetry (DSC) showed that the glass transition temperature of the hybrid materials increases with increasing of SiO₂ composition. Photographs of scanning electron microscopy (SEM) and atomic force microscopy (AFM) inferred that the size of the inorganic particles in the hybrid materials was less than 20 nm. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 1607–1613, 1998     

Crosslinking effects on hybrid organic–inorganic proton conducting membranes based on sulfonated polystyrene and polysiloxane

New hybrid semi‐interpenetrating proton‐conducting membranes were obtained using sulfonated polystyrene (SPS) and inorganic–organic polysiloxane phases with the aim of improving the mechanical and thermal characteristics of the pristine polymer and to study the effects of crosslinking in the latter phase in several of their properties, mainly proton conductivity. Siloxane phases were prepared using poly(dimethylsiloxane) (PDMS) and PDMS with tetraethoxysilane (TEOS) or phenyltrimethoxysilane (PTMS) as crosslinking agents. To study the crosslinking effect, membranes were prepared with different TEOS:PDMS and PTMS:PDMS mole ratios. The films obtained were characterized by FTIR, ²⁹Si‐HPDEC MAS‐NMR, ¹³C‐CP‐MAS NMR, elemental and thermal analyses. Certain properties, such as water uptake (WU), ion exchange capacity (IEC) and the state of the water, were determined. The proton conductivity was measured at different temperatures (30°C and 80°C) and relative humidities (50–95%). The water content of the hybrid membranes declined significantly, compared with the SPS membranes, depending on the nature and amount of siloxane phase added. Nonetheless, the conductivity values remained relatively high (>100 mS cm^?1 at 80°C and 95% RH) when compared to Nafion®117 presumably because of the formation of well developed proton channels, which makes them potentially promising as proton exchange membranes for fuel cells. These membranes proved to be thermally stable up to 350°C. Scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) were used to characterize the hybrid membranes microstructures; the latter provided contrast for the conductive domains. Copyright © 2015 John Wiley & Sons, Ltd.     

利用聚乙烯醇结晶辅助制备多重交联的高强度聚丙烯酰胺水凝胶

在表面带有C=C双键的乙烯基杂化二氧化硅纳米颗粒(vinyl hybrid silica nanoparticle,VSNP)上接枝丙烯酰胺(AM),所得到的纳米刷状凝胶因子通过聚丙烯酰胺(PAM)间的氢键形成物理交联点,则多官能化的VSNP可作为拟共价交联点构筑双重交联的单一网络纳米复合物理水凝胶(nanocomposite physical hydrogel,NCP gel),表现出较高的强度和超拉伸性.为了进一步提高凝胶的强度和韧性,将少量PVA和PAM/VSNP纳米刷混合制成凝胶,通过冷冻-融化处理,使与PAM分子链相互缠绕并形成氢键作用的PVA结晶,形成新的交联点进一步交联PAM NCP gel,得到多交联的PAM NCP gel体系.通过拉曼光谱和示差扫描量热分析,证明凝胶中的PVA通过氢键既可以与PAM相互作用,又形成微晶为新交联点,大大增强了NCP gel的力学性能,与PAM NCP gel相比,凝胶的拉伸强度和断裂能分别从313 k Pa和1.41×104 J/m~2提高到了557k Pa和4.65×104 J/m~2.     

UV Curable Hard Transparent Hybrid Coating Materials on Polycarbonate Prepared by the Sol-Gel Method

UV curable, hard, transparent inorganic/organic composites with covalent links between the inorganic and the organic networks were prepared by the sol-gel method. These hybrid coating materials were synthesized using a commercially available, acrylate end-capped polyester or polyurethane oligomeric resin (EBC80, EBC284), hexanedioldiacrylate (HDDA) as a reactive solvent, 3-(trimethoxysilyl)propoxymethacrylate (TMSPM) as a coupling agent between the organic and inorganic phase, and a metal alkoxide, tetraethylorthosilicate (TEOS). The materials were applied on primer or oxygen plasma pretreated polycarbonate sheets and UV cured, followed by a thermal treatment to give a transparent coating with a good adhesion and abrasion resistance. The high transmission and the thermogravimetric behavior indicate the presence of a nanoscale hybrid composite, as is confirmed by SAXS and TEM measurements. In a Taber Abrasion Test, uncoated polycarbonate sheets exhibit a 48% decrease in light transmittance at 600 nm after 300 wear cycles, whereas the EBC80 hybrid coating system containing 9 wt% SiO₂ (EBC80/25Si) shows only 28% decrease in light transmittance. A maximal improvement of the abrasion resistance is achieved when 23 wt% SiO₂ is incorporated (EBC80/60Si, EBC284/60Si) with only 20% decrease in light transmittance. The abrasion resistance of glass is not yet encountered. For optimal results, it is essential that the rate of condensation of the silanol groups is sufficiently high to form a dense three-dimensional network.     

Redox‐Active Hybrid Polyoxometalate‐Stabilised Gold Nanoparticles

We report the design and preparation of multifunctional hybrid nanomaterials through the stabilization of gold nanoparticles with thiol‐functionalised hybrid organic–inorganic polyoxometalates (POMs). The covalent attachment of the hybrid POM forms new nanocomposites that are stable at temperatures and pH values which destroy analogous electrostatically functionalised nanocomposites. Photoelectrochemical analysis revealed the unique photochemical and redox properties of these systems.     

Redox-Active Hybrid Polyoxometalate-Stabilised Gold Nanoparticles

We report the design and preparation of multifunctional hybrid nanomaterials through the stabilization of gold nanoparticles with thiol-functionalised hybrid organic–inorganic polyoxometalates (POMs). The covalent attachment of the hybrid POM forms new nanocomposites that are stable at temperatures and pH values which destroy analogous electrostatically functionalised nanocomposites. Photoelectrochemical analysis revealed the unique photochemical and redox properties of these systems.