Structure-property behavior of new hybrid materials incorporating oligomeric poly(tetramethylene oxide) with inorganic silicates by a sol-gel process

Novel transparent hybrid materials incorporating triethoxysilane endcapped poly(tetramethylene oxide) with tetramethoxysilane have been successfully prepared by a sol-gel process. The molecular weight of PTMO has been varied to study its effect on the structure-property behavior of these hybrid materials. Mechanical properties and dynamic mechanical behavior have been measured; small angle X-ray scattering (SAXS) has been utilized to obtain structural information. Based on the experimental results, a simplified morphological model has been suggested to describe these new hybrid systems.     

溶胶-凝胶法制备γ-缩水甘油醚丙基三甲氧基硅烷/正硅酸乙酯杂化材料研究

采用溶胶-凝胶工艺制备γ-缩水甘油醚丙基三甲氧基硅烷/正硅酸乙酯(GPTMS/TEOS)杂化材料,采用正交实验法对H2O与S i的摩尔比、GPTMS与TEOS摩尔比、水解时间等影响材料性能的因素进行了优化,用热失重(TGA)和动电位扫描法研究分析了该材料的结构、耐热及防腐保护性能。结果表明:当GPTMS∶TEOS=1∶3(摩尔比),H2O∶S i=11.25∶1(摩尔比)时,该材料的耐热性及防腐保护性能最优,X射线衍射分析表明,该材料结构为非晶态结构。     

New hybrid materials incorporating tetrabutyl titanate and tetraethoxysilane with functional SEBS elastomer via the sol-gel process: Synthesis and characterization

New flexible hybrid materials were prepared by incorporating amino-functionalized styrene-ethylene-butylene-styrene block copolymer (SEBS elastomer) with tetrabutyl titanate and tetraethoxysilane. SEBS was modified via nitration and subsequent reduction, giving the product SEBS II bearing amino groups in the hard segments. The trimethoxylsilane functionalization was then achieved by the addition of coupling agent, 3-glycidyloxypropyl trimethoxysilane (GOTMS) in the sol-gel processing. The hydrolytic condensation of these trimethoxylsilane groups on SEBS II with metal alkoxide led to the formation of covalent bonds between the organic polymer chains and the inorganic networks produced in situ to prevent macrophase separation, resulting in better optical properties. Electron micrographs clearly show that the size of dispersed inorganic phase can be reduced by the use of trimethoxyl silane functionalization. The results of dynamic mechanical analysis are also discussed. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 66: 853–860, 1997     

溶胶-凝胶法制备纳米SiO2/环氧树脂杂化材料

采用溶胶凝胶（Sol-Gel）法,以正硅酸乙酯（TEOS）为无机先驱体,γ-甲基丙烯酰氧丙基三甲氧基硅烷（KH-570）为偶联剂,氨水为催化剂,制备了纳米SiO2／环氧树脂杂化材料以有效控制纳米粒子在基体树脂中的分散。考察了共溶剂乙醇对溶胶-凝胶过程的影响,通过力学性能测试研究了TEOS和KH-570用量对杂化材料性能的影响并通过扫描电镜（SEM）对杂化材料的微观结构进行了表征。结果表明：TEOS质量分数为3％,KH-570质量分数为2％时杂化材料拉伸强度和弯曲强度分别提高9％和10％。杂化材料断口形貌有明显的波纹状,表现为韧性断裂。该方法能够实现无机成分和有机环氧树脂在分子级别上的复合,制备出高性能杂化材料。     

Study on acrylic resin/titania organic-inorganic hybrid materials prepared by the sol-gel process

Acrylic resin/titania organic-inorganic hybrid materials were prepared by the two approaches. One approach (BL method) was blending titania produced by the sol-gel process with synthesized acrylic resins containing various content of acrylic acid (AA). Another approach (IS method) was the in situ polymerization of acrylic monomers in synthesized titania sols. The structure and mechanical, thermal and optical properties of the hybrid films were investigated by small angle X-ray scattering (SAXS), atomic force microscopy (AFM), dynamic mechanical analysis (DMA), Instron testing machine, thermogravimetric analysis (TGA) and ultraviolet-visible spectroscopy (UV-VIS), respectively. Titania phase in the hybrids showed an open structure and nano-scale size. However, aggregation of titania occurred in the systems prepared by IS method or without AA contained. The mechanical properties, thermal stability and UV shielding properties of organic polymer were obviously improved with titania networks embedded. It was found that BL method could prepare homogeneous hybrids with better integrative mechanical properties in comparison with IS method.     

Properties of PVC-titania hybrid materials prepared by the sol-gel process

Hybrid materials from Polyvinyl chloride (PVC) and titania were prepared using sol-gel technique. In-situ generation of titania network in the PVC matrix was carried out by introducing required amounts of tetrapropylorthotitanate (TPOT) followed by hydrolysis/condensation of TPOT in the matrix. Homogeneous and semi-transparent films were obtained by casting and solvent evaporation. Mechanical properties of these films up to 15 wt. % titania contents were studied. The results showed an increase in the Young's modulus, length at rupture and toughness of the unplasticised PVC. However, the tensile strength and stress at break point decreased with the addition of titania contents. Thermal stability of the material was studied using dehydrochlorination (DHCl) technique and thermogravimetric analysis. The PVC samples with small amount of titania were found to be more stable as compared with the pure PVC. Received: 13 October 1997/Revised version: 22 January 1998/Accepted: 2 February 1998     

有机硅对无机层状材料的插层处理

主要介绍了无机层状材料的结构、插层的方法、插层产物的表征等。     

Hybrid materials derived from modified styrene-butadiene-styrene copolymer (SBS) and silica through the sol-gel process

Non-bonded and covalently bonded organic-inorganic hybrids materials, SBS-NO₂/SiO₂, SBS-NH₂/SiO₂ and SBS-Si(OCH₃)₃/SiO₂, were prepared by the sol-gel process using tetraethoxysilane (TEOS) in presence of modified SBS, SBS-NO₂, SBS-NH₂ and SBS-Si(OCH₃)₃, respectively, with HCl as a catalyst. The modified SBS was prepared without damage its molecular weight and chemical structure, which was identified by the means of FTIR spectroscopy, elementary analysis, and Wijs titration. The interfacial force and the properties such as hemical resistance, elongation, thermal stability, and dynamic mechanical properties of the hybrids were investigated in detail.     

Simultaneous milling and coating of inorganic particulates with polymeric coating materials using a fluid energy mill

A fluid energy–based method and apparatus was used to simultaneously mill and coat coarse particles with the presence of various coating materials, including: three micron‐sized particles—carnauba wax, polyethylene (PE), and polytetrafluoroethylene (PTFE) particles, and one type of nanoparticle, PTFE. The coating performance of polymeric materials and their effect on the breakage of the coarse particles were studied. The Young's modulus of the coating materials and the materials' size ratio were found to be critical in controlling the coating quality. The polymeric coating, working as a lubricant and cushion layer, absorbs part of the high kinetic energy and results in the larger particle size of fluid energy mill–ground product. Experimental and simulation results suggest that side‐sweep attrition plays a role in breakage of core particles. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Preparation and characterization of multicomponent porous materials prepared by the sol-gel process

An experimental strategy was developed to obtain transparent Si-Al-Ti-Ni-Mo and Si-Zr-Ti-Ni-Mo sols via the sol-gel process. The sol was prepared from Si(OEt)₄ (TEOS), Al(OBu^s)₃ (OBu^s: C₂H₅CH(CH₃)O), Ti(OEt)₄ (OEt: OCH₂CH₃), Zr(OPrⁿ)₄ (OPrⁿ: OCH₂CH₂CH₃). In both cases nickel nitrate hexahydrate (Ni(NO₃)₂ · 6H₂O) and ammonium heptamolybdate tetrahydrate ((NH₄)₆Mo₇O₂₄ · 4H₂O) were the Ni and Mo sources, respectively. The sols were characterized by Fourier Transform Infrared Spectroscopy (FTIR). Assignments of the simultaneous formation of the Si-O-Al, Si-O-Ti, Si-O-Ni, and Si-O-Zr bonds were done. The sols were polymerized at room temperature (293 K) to obtain gels, and these were dried at 423 K and calcined at 573, 853 and 893 K in air. The characterization techniques used were small-angle X-ray scattering (SAXS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and ²⁹Si and ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR). The density of the solids was measured following ASTM method D-4892 and the porosity and surface area were determined by N₂ adsorption/desorption isotherms. The corresponding average pore diameters were evaluated using the BJH, HK, and DA methods.     

Synthesis and optical properties of novel side chain NLO organic/inorganic polymers via sol-gel process

Summary Novel side chain NLO organic/inorganic polymers were developed by sol-gel process of dye-contained triethoxysilane with tetraethoxysilane. A NLO moiety based on 4-[N, N-bis(2-hydroxyethyl)amino]-4-nitrostilbene (diol-DANS) was covalently bounded to the triethoxysilane derivative. The sol-gel derived NLO polymers were analyzed by analytic techniques, including FT-IR, TGA, solid state ²⁹Si-NMR, SEM, etc. The incorporation of the DANS dye into silicon oxide networks induces high dimensional stability of dipole alignment and the easy film fabrication. They exhibited a significant improvement in the thermal stability at high temperatures exceeding 270°C. The electro-optic coefficient at 1.3 m is 4.3 pm/V for the copolymer containing 50 wt % of the dye-contained triethoxysilane system poled with corona discharge and is shown excellent long-term stability with 80% of initial value even after 3 hrs at 150°C.     

Hybrid organic/inorganic coatings produced using a dual-cure mechanism

A coating precursor containing both acrylate functionality and trimethoxysilane functionality was produced by reacting bisphenol-A glycerolate diacrylate with 3-isocyanatopropyltimethoxysilane. With this precursor, two different crosslinked networks can be produced. A polyacrylate network can be produced using a radiation-cure mechanism while a polysiloxane network can be produced by hydrolysis and condensation reactions involving the trimethoxysilane groups. The objective of the study was to determine the utility of this dual-cure system for generating rapid-cure coatings for corrosion protection. Coating properties were determined as a function of cure conditions. The results of the study showed that the formation of siloxane crosslinks was significantly hindered by the crosslinked network induced by the UV-curing process. Even though the overall conversion of trimethoxysilane groups to siloxane crosslinks was relatively low, coating barrier properties were significantly enhanced and coating free volume reduced. At ambient conditions, additional crosslinking occurring through siloxane bond formation increased within the first 4 days after UV-curing. Beyond this period, siloxane bond formation remained unchanged as did coating properties.     

Preparation of urania and urania-zirconia microspheres by a sol-gel process

The sol-gel process was originally developed and applied at the Oak Ridge National Laboratory for preparation of high-density thoria-urania fragments and microspheres for nuclear reactor fuels. The application of the process for preparation of microspheres to sols of urania, urania-zirconia, and urania-carbon is reported in this paper. Relatively high-strength, spherical particles of UO₂, UO₂-ZrO₂, and UC₂ were prepared with diameters of 50-500 microns and densities of 80-100% of the theoretical densities.     

Preparation and characterizations of a new PS/TiO2 hybrid membranes by sol-gel process

New organic-inorganic hybrids based on PS/TiO₂ hybrid membranes were prepared by sol-gel and phase inversion process. The membranes were characterized in terms of morphology, structure, hydrophlicity, UF performance and thermal stability. The results showed that macrovoids were nearly suppressed with formation of a sponge like membrane structure. The TiO₂ particles were uniformly dispersed in membrane. The nanodispersed inorganic network formed after sol-gel process and the strong interaction between inorganic network and polymeric chains led to the improvement of porosity and thermal stability. In particular hydrophilicity and permeability increased drastically with the increasing of TiO₂ content in the range of 0-9.3 wt%, without changing retention properties of membrane. However, high-TiO₂ concentration induces nanoparticles aggregate, resulting in the decline of hydrophilicity and permeability. Thus, PS/TiO₂ hybrid membranes with proper TiO₂ content are desirable to meet some specific requirements in industrial separation.     

A covalent organic/inorganic hybrid proton exchange polymeric membrane: synthesis and characterization

Commercial polyetheretherketone (Victrex PEEK) was sulfonated up to 90% degree of sulfonation (DS), then reacted with SiCl₄ to obtain a hybrid polymer. The product was characterized by ²⁹Si NMR and ATR/FTIR spectroscopies demonstrating the formation of covalent bonds between the organic and inorganic components. No dispersed inorganic silicon was present in the product as evidenced by the lack of any resonance at δ<−100 ppm. Despite the high DS the physicochemical properties of the hybrid were suitable for the preparation of membranes exhibiting high and stable conductivity values (10⁻² S/cm), hence suitable for application as ion exchange membrane.     

C60-containing nanostructured polymeric materials with potential biomedical applications

Star-shaped polymers with a fullerene (C₆₀) core and an unexpanded structure were successfully prepared by reaction of C₆₀ with amino end-capped polyesters H_xC₆₀(NHPCL_n)_x and polyethers H_xC₆₀(NHPEG_n)_x, respectively. Upon irradiation of these C₆₀-derivatives, a large amount of singlet oxygen was released. Compared to previously synthesized star-shaped azafulleroids with an expanded structure, the photosensitivity of H_xC₆₀(NHPCL_n)_x is higher as assessed by a higher production of singlet oxygen. The cytotoxicity of the photoactive water-soluble H_xC₆₀(NHPEG_n)_x derivatives was tested against THP-1 cells and expressed in terms of cell viability. Moreover, they were processed as micro-/nanosized fibers by electrospinning, which however required the addition of poly(?-caprolactone) (PCL). The diameter distribution of the fibers was trimodal, where the fraction with the 270 nm average diameter was the major population. Because of their photoactivity, the herein reported star-shaped C₆₀-derivatives are promising candidates for photodynamic cancer therapy and treatment of multidrug resistant pathogens.     

溶胶-凝胶法制备SiO_2/水性聚氨酯杂化材料研究进展

主要介绍了有机-无机杂化材料的特点、溶胶-凝胶法的原理,并对溶胶-凝胶法制备二氧化硅(SiO_2)/水性聚氨酯(WPU)杂化材料的不同作用类型进行了综述。最后对SiO_2/WPU杂化材料存在的问题提出了解决措施及相关的建议,并对该杂化材料的发展方向进行了展望。