聚醋酸乙烯酯／二氧化硅杂化材料的制备与性能研究

以硅酸钠在HCL溶液中的水解，经四氢呋喃（THF）萃取，制备聚硅酸溶胶，再与聚醋酸乙烯酯（PVAC）的THF溶液混合，经溶胶-凝胶过程制备了PCAC/SiO2有机/无机杂化材料。用扫描是镜（SEM），红外光谱（IR），X射线衍射，热失重及透光率等的分析测试，对制备的PVAC/SiO2杂化材料进行了结构与性能的研究。结果表明：本法制备的杂化材料中SiO2在PVAC的基体中分布均匀，SiO2在非晶态的PVAC中亦呈无定形态，杂化材料的硬度、软化温度和热分解温度都比纯PVAC有较大的提高；SiO2含量少于40%的杂化材料其断裂伸长率、屈服强度和断裂强度也比纯PVAC提高；另外，还发现在制备过程中加入少许偶联剂KH-570后，杂化材料中的有机-无机相间的相容性增加，不易发生相分离，材料的透光性能也大为改善。     

PBMA-SiO2杂化纤维的制备及表征

以正硅酸乙酯(TEOS)和聚甲基丙烯酸丁酯(PBMA)为前躯体,乙烯基三乙氧基硅烷(VTEOS)为偶联剂,通过溶胶-凝胶法制备了SiO2纤维和PBMA/SiO2杂化纤维,并使用IR、SEM、TGA等进行了结构与性能表征,研究了溶胶的杂化反应机理、成纤性能.结果表明:硅烷偶联剂的引入使得PBMA-SiO2杂化纤维均匀性较好,纤维中有机相与无机相之间通过化学键连接,实现了有机-无机组分的充分贯穿;其耐热性能优于纯PBMA.     

环氧树脂/二氧化硅杂化材料的制备与性能表征

溶胶-凝胶法制备环氧树脂/SiO2杂化材料,利用FTIR、SEM和综合热分析仪对杂化材料的结构、显微形态及热性能进行了表征.结果表明,杂化材料中SiO2与环氧树脂两相间存在氢键作用;SiO2质量分数＜7%时SiO2与环氧树脂之间无明显相界面,可获得有机聚合物链段与无机网络互穿的有机/无机杂化材料;SiO2质量分数为11%时材料具有最佳耐热性能.     

聚甲基丙烯酸丁酯-二氧化硅杂化材料的制备及性能

用硅酸钠制备了聚硅酸溶胶，作为制备有机／无机杂化材料的无机组分前驱物，以甲基丙烯酰氧丙基三甲氧基硅烷为偶联剂，通过溶胶-凝胶技术与甲基丙烯酸丁酯制得两相间有共价键结合的透明聚甲基丙烯酸丁酯／二氧化硅杂化材料。用红外光谱、透射电镜、TG和DSC等对杂化材料进行了表征，热失重分析表明，杂化材料的热稳定性随SiO2含量的增加而提高，且杂化材料的玻璃化温度Tg也有一定的提高，同时杂化材料的透光率可达80％，硬度比纯PBMA有很大的提高。     

溶胶-凝胶法制备无机纳米/聚酰亚胺杂化膜及其表征

采用溶胶-凝胶法制备了SiO2及A12O3溶胶,并将其掺入到聚酰胺酸基体中,得到无机纳米SiO2-Al2O3/聚酰亚胺杂化膜,并对其结构性能进行了研究.实验表明,薄膜材料中无机纳米SiO2和Al2O3粒子分散均匀,与有机相存在键合;材料热分解温度有所提高.     

PMMA／SiO2杂化纤维的制备及表征

以正硅酸乙酯(TEOS)和PMMA低聚体为原料,乙烯基三乙氧基硅烷(VTEOS)为偶联剂,采用溶胶-凝胶法制备了PMMA/SiO2杂化溶胶,陈化后用提拉法制得PMMA/SiO2杂化纤维。研究了溶胶的杂化反应机理、成纤性能;使用IR、SEM、TGA及DSC分析了杂化纤维的结构与性能。结果表明,该杂化溶胶具有很好的拉丝性能,黏度为180 Pa.s~300 Pa.s时的成纤性能好,所制得的杂化纤维,其中PMMA与SiO2之间通过化学键连接,在纤维内部有机无机相间形成均一的连续相;其耐热性能优于纯PMMA。     

PEG/SiO2-TiO2杂化纤维的制备与表征

以正硅酸乙酯(TEOS)和钛酸四丁酯(TBT)为无机前驱体,采用溶胶-凝胶法制备了PEG/SiO2-TiO2杂化溶胶,通过提拉法制得杂化纤维,并对其进行了简单表征.结果表明,随钛硅物质的量比的增加或有机相质量的增加,溶胶的可纺性变好;有机相与无机相之间通过化学键连接;纤维直径为40μm左右;TiO2的引入增强了其抗紫外性,杂化纤维的耐热性优于纯PEG.     

聚己内酯/ 环氧树脂/ SiO2杂化材料的制备及性能

采用端硅氧烷基聚己内酯( PCL-TESi) 作为无机前躯物, 通过环氧树脂/ KB-2 的固化反应和PCL-TESi的溶胶2凝胶过程, 制备了聚己内酯/ 环氧树脂/ SiO₂ ( PCL/ EP/ SiO₂ ) 有机-无机杂化材料。利用红外光谱、透射电镜( TEM) 、热失重分析( TGA) 及在甲苯溶液中的溶胀试验对不同SiO₂ 含量的杂化材料进行分析。研究发现, 随着PCL-TESi 含量增大杂化体系交联密度降低; 此杂化体系中存在环氧和Si —O —Si 两种交联网络, 微观上形成纳米两相结构; Si —O —Si 交联网络的形成显著提高了材料的耐热性能, 使失重5 %时的热分解温度从120.5 ℃(纯环氧树脂/ KB-2 体系) 提高到277.6 ℃(SiO₂质量分数为3. 84 %的杂化体系) 。      

PMMA/SiO_2-TiO_2杂化纤维的制备与表征

以正硅酸乙酯和钛酸四丁酯为前驱体,乙烯基三乙氧基硅烷为偶联剂,采用溶胶凝胶原位聚合法制备了聚甲基丙烯酸甲酯/二氧化硅-二氧化钛(PMMA/SiO2-TiO2)杂化溶胶,陈化后用提拉法制得杂化纤维。研究了溶胶的杂化反应机理;使用红外光谱(IR)、扫描电子显微镜(SEM)、紫外-可见光谱(UV-Vis)、荧光光谱(FL)和热重分析(TGA)分析了杂化纤维的结构与性能。结果表明,PMMA与SiO2-TiO2之间通过化学键连接;纤维直径为150μm,在纤维内部有机无机相间形成均一的连续相;TiO2的引入增加了其抗紫外性;杂化纤维具有荧光性能;其耐热性能优于纯PMMA。     

PDMS/SiO2杂化材料的合成与性能研究

采用草酸作为催化剂,通过溶胶-凝胶(Sol-Gel)反应制得了透明的块状聚二甲基硅氧烷/SiO2有机-无机杂化材料,并采用FTIR、TG等方法对所制备的杂化材料进行了分析表征,考核了杂化材料的硬度.结果表明:所制备的杂化材料中的硬度随PDMS用量、分子量以及H2O/TEOS的摩尔比的增加而降低,其热重损失率随PDMS用量的增加而下降.     

聚乙烯醇/二氧化硅共混膜的制备及耐温、耐溶剂性能研究

以聚乙烯醇（PVA）和正硅酸乙酯（TEOS）为原料,通过溶胶－凝胶（Sol-Gel)方法,制备出不同二氧化硅含量的聚乙烯醇／二氧化硅（PVA／SiO2)共混均质膜。通过热重分析（TGA）、示差扫描量热法（DSC）和动态力学分析（DMA）研究了共混膜的热性能。结果表明,与PVA膜相比,PVA／SiO2共混膜具有更高的热稳定性,随SiO2含量的增大,共混膜的分解温度升高,玻璃化温度也略有提高。以水为溶剂,测定了共混膜的耐溶剂性能。与PVA膜相比,PVA／SiO2共混膜的耐溶剂性能有显著的提高。     

Biomimetic approach to the formation of gold nanoparticle/silica core/shell structures and subsequent bioconjugation

The encapsulation of individual nanoparticles has gained great attention as a method for both stabilizing nanoparticles and tailoring their surface properties. In particular, the encapsulation of nanoparticles with silica shells is advantageous for bioconjugation and applications to (nano)biotechnology. Herein we report a method for constructing gold nanoparticle (AuNP)/silica core/shell hybrid structures by biomimetic silicification of silicic acids. The procedure consists of surface-initiated, atom transfer radical polymerization of 2-(dimethylamino)ethyl methacrylate (DMAEMA) from AuNPs and biomimetic polycondensation of silicic acids by using poly(DMAEMA) as a synthetic counterpart for silaffins that are found in diatoms. The resulting AuNP/silica hybrids were characterized by Fourier transform infrared spectroscopy, energy dispersive x-ray spectroscopy, UV-vis spectroscopy and transmission electron microscopy. In addition, the immobilization of biological ligands onto the hybrids was investigated for potential applications to biotechnology. As a model ligand, biotin was attached onto the AuNP/silica hybrids through substitution reaction and Michael addition reaction, and the attachment was confirmed by fluorescence microscopy after complexation with fluorescein-conjugated streptavidin.     

含共轭结构的ZnO/聚乙烯醇复合光催化材料的制备与性能

以ZnO和NaOH为原料,采用低温水热法合成纳米ZnO 半导体材料,并与聚乙烯醇（PVA）水溶液在超声作用下混合,通过直接煅烧制备出PVA中含共轭双键碳链结构（C）的ZnO/PVA_C复合光催化材料。采用 SEM、XRD、FTIR、Raman和UV-Vis DRS对样品进行表征。结果表明:ZnO/PVA_C复合光催化材料由结晶性能良好的纳米ZnO和具有共轭结构的聚合物组成,且界面间通过化学键Zn-O-C相连接;在模拟太阳光照射下,ZnO/PVA_C复合光催化材料对光的吸收响应可扩展到整个可见光区,并产生较高光电流。光催化性能测试结果表明,ZnO/PVA_C复合光催化材料对罗丹明B的降解催化性能（30 min降解率接近于100%）明显高于纯纳米ZnO。      

Toroidal microporous silica gel

Microporous amorphous silica gel with a characteristic toroidal form of the elementary particles, has been prepared by thermal dissociation of a solution of silicic acid in a spray dryer. The substance obtained was investigated by electron microscopy, infra-red spectroscopy and thermal analysis. The adsorption properties were studied by lowtemperature adsorption of nitrogen.     

Transparent anti-stain coatings with good thermal and mechanical properties based on polyimide-silica nanohybrids

In this work, we synthesized polyimide/silica hybrid materials via sol-gel method using a fluorinated poly(amic acid) silane precursor and a variety of perfluorosilane contents. We studied the influence of a hybrid coating film with the following characteristics; hydrophobicity, oleophobicity, optical transparency, and surface hardness of the coating films. The hybrid coatings with the fluorosilane contents up to 10 wt% are optically transparent and present good thermal stability with a degradation temperature of > 500 degrees C as well as a glass transition of > 300 degrees C. Both water contact angle and oil contact angle increase rapidly with introducing small amount of the fluorosilane in the hybrids and reaches the maximum of 115 degrees and 61 degrees, respectively. The hardness of the hybrid coatings increases up to 5H with an increase of the FTES content in the hybrids. These colorless, transparent, and thermally stable hybrid materials could be suitable for applications as anti-stain coatings.     

Improvements in transmittance,mechanical properties and thermal stability of silica–polyimide composite films by a novel sol–gel route

Sol–gel process has been frequently employed for preparation of silica/polyimide composite films. In this article, a novel sol–gel route is introduced to prepare silica (SiO₂)/polyimide (PI) (PS2 system) composite films and to enhance the compatibility between the polyimide and silica. The transmittance, mechanical properties, thermal stability, and morphology of the PS2 composites are studied and compared with the PS1 films prepared by the traditional sol–gel route. The results show that the transmittance, mechanical properties and thermal stability of the PS2 composites are significantly improved especially at high silica contents when compared with those of their counterparts prepared by the traditional sol–gel route. This is explained in terms of the silica particle size and dispersion in the two composites. In addition, the effect of silica particle size on the thermal expansion of silica/PI films is also examined.     

Thermosensitive phase behavior and drug release of in situ N-isopropylacrylamide copolymer

In this work, a novel in situ gel based on N-isopropylacrylamide as monomer and acrylate terminated poly(l-lactic acid)-b-poly(ethylene glycol)-poly(l-lactic acid) (PLEL) as biodegradable crosslinker was studied. The prepared poly(N-isopropylacrylamide) (PNIPAM) copolymer undergoes a temperature-dependent sol–gel transition, for it is a flowing sol at ambient temperature and turns into a non-flowing gel at around physiological body temperature. The sol–gel phase transition was recorded by using the methods of test tube‐inverting and differential scanning calorimetry (DSC), which depended not only on chemical composition of copolymer, but also on molecular weight of poly(ethylene glycol) (PEG) of PLEL. The in vitro release behaviors showed that ofloxacin as model drug could be released sustainedly from the PNIPAM copolymer hydrogel system. Therefore, PNIPAM copolymer hydrogel might be very useful for its application in biomedical fields such as injectable drug delivery system.     

Preparation of bioactive glass-polyvinyl alcohol hybrid foams by the sol-gel method

A new class of materials based on inorganic and organic species combined at a nanoscale level has received large attention recently. In this work the idea of producing hybrid materials with controllable properties is applied to obtain foams to be used as scaffolds for tissue engineering. Hybrids were synthesized by reacting poly(vinyl alcohol) in acidic solution with tetraethylorthosilicate. The inorganic phase was also modified by incorporating a calcium compound. Hydrated calcium chloride was used as precursor. A surfactant was added and a foam was produced by vigorous agitation, which was cast just before the gel point. Hydrofluoric acid solution was added in order to catalyze the gelation. The foamed hybrids were aged at 40 ^∘C and vacuum dried at 40 ^∘C. The hybrid foams were analyzed by Scanning Electron Microscopy, Mercury Porosimetry, Nitrogen Adsorption, X-ray Diffraction and Infra-red Spectroscopy. The mechanical behavior was evaluated by compression tests. The foams obtained had a high porosity varying from 60 to 90% and the macropore diameter ranged from 30 to 500 μ m. The modal macropore diameter varied with the inorganic phase composition and with the polymer content in the hybrid. The surface area and mesopore volume decreased as polymer concentration increased in the hybrids. The strain at fracture of the hybrid foams was substantially greater than pure gel-glass foams.     

Synthesis and characterisation of cellulose/silica hybrids obtained by heteropoly acid catalysed sol–gel process

Cellulose/silica hybrids (CSHs) were synthesized by a sol–gel method using eucalyptus bleached kraft pulp as cellulose source and tetraethyl orthosilicate (TEOS) as the silica precursor in the presence of heteropoly acids (HPAs) as catalysts. HPAs, and especially tungstophosphoric acid H₃PW₁₂O₄₀, showed better catalytic efficiency than conventional mineral acids. Silica was deposited on fibres in the form of a thin film or mesoparticles as revealed by SEM/EDS and AFM analyses. Roughly 40–60% of silica was incorporated into cellulosic material considerably diminishing its hydrophilicity and improving thermal stability. CSHs were structurally characterised by FTIR, ¹³C and ²⁹Si solid state NMR. It was suggested that proportions of Q², Q³ and Q⁴ structures in silica counterpart depended on the synthesis conditions (H₂O/TEOS molar ratio and catalyst concentration among others). A clear relationship between the thermal stability of CSH and the degree of silica crosslinking in hybrids has been observed.     

硅灰石制备多孔高比表面积二氧化硅机理探讨

通过对用硅灰石与盐酸反应制备多孔高比表面积SiO2最佳实验工艺条件的研究,确定了最佳试验工艺条件,即反应速度、反应时间、中和速度、反应最终pH值与SiO2比表面积的关系,探讨了其合成的机理。研究结果表明,当pH≤1.0时,硅灰石与盐酸反应生成大量稳定的硅酸溶胶;反应最终(pH＝4.0)使硅酸水解和缩聚以及Si—O与OH基团氢键的形成以适宜的速度进行,形成弱交联、网状、低密度的硅酸凝胶,最终产物SiO2的比表面积增大。