自组织多孔海绵状有机-无机杂化二氧化硅

经由溶胶.凝胶过程,利用硅试剂制备出新颖的多孔海绵状有机-无机杂化二氧化硅.使用冷场发射扫描电镜(FESEM),表征了多种反应条件下样品的形貌.这种杂化二氧化硅海绵体能快速吸收水和有机溶剂,每克能吸收12.2 mL溶剂.     

光固化环氧丙烯酸酯有机-无机杂化体系

二氧化硅杂化体系;溶胶-凝胶法;光固化环氧丙烯酸酯有机-无机杂化体系     

有机-无机杂化介孔二氧化硅在环境保护中的应用

将有机基团通过后嫁接或共缩聚法引入到介孔二氧化硅的孔道表面或骨架中,根据有机基团在材料中的位置可得到表面结合型和桥键型两类功能化介孔材料.本文总结了有机-无机杂化介孔二氧化硅的分类及合成方法,重点介绍了该类材料作为吸附剂在环境保护中的应用,包括金属阳离子、含氧阴离子、有机污染物和气体的去除与回收.并展望了有机-无机杂化...     

用ATRP方法制备聚苯乙烯/纳米二氧化硅杂化粒子

采用过量的甲苯-2,4-二异氰酸酯(TDI)对SiO₂纳米粒子表面进行修饰, 将原子转移自由基聚合(ATRP)引发剂引入到SiO₂粒子表面合成大分子引发剂, 采用ATRP技术将聚苯乙烯(PS)大分子链接枝到SiO₂表面制备出以纳米二氧化硅为核, 聚苯乙烯为壳的PS/SiO₂杂化粒子. 利用红外光谱(FTIR)、核磁共振谱( NMR)、凝胶色谱(GPC)等实验手段对杂化粒子及表面接枝聚苯乙烯进行了表征分析.     

聚酰亚胺-二氧化硅杂化膜的制备及表征

 采用溶胶－凝胶法制备了两类具有不同二氧化硅含量的聚酰亚胺－二氧化硅（PI－SiO2）杂化膜,并用SEM,IR,TG－DTA,氮吸附和气体渗透性能测试等手段对该膜材料的表面形貌、结构、热性能、孔径分布和气体渗透性能进行了表征．结果表明,PI－SiO2膜材料中SiO2粒子的分散良好,与有机相之间存在着分相和键联;膜材料的玻璃化温度θg均随SiO2含量的增加而升高．相比之下,在酸性条件下制备的T系列杂化膜比在碱性条件下合成的S系列杂化膜对θg的影响更大一些;杂化膜具有较好的气体渗透性能和亲水性能,其H2O／N2和H2O／CH4的分离系数远大于努森扩散的理论值．     

通过RAFT聚合制备SiO2/接枝共聚物纳米杂化粒子

以二氧化硅(SiO2)纳米粒子表面键接的二硫代苯甲酸酯作为可逆加成-断裂-链转移(RAFT)聚合反应的链转移剂, 在室温下引发苯乙烯和马来酸酐进行表面RAFT交替共聚反应, 制得了SiO2/苯乙烯-alt-马来酸酐杂化材料. 通过聚氧化乙烯(PEO)的羟基与马来酸酐的酯化反应, 将PEO接枝到SiO2纳米粒子的表面, 增加了硅粒子的生物相容性. 用FTIR, TGA和TEM对杂化材料的结构、组成和形貌进行了表征.     

二氧化硅-共聚物杂化荧光纳米材料用于动物活体成像

以氧化硅（SiO₂）前驱体与三嵌段共聚物F108合成较小粒径的SiO₂-共聚物杂化纳米体系（SNP），并与高效近红外发射的疏水染料M507自组装，构建了近红外发光纳米探针M507@SNP。同时，研究了M507@SNP的光物理性能和细胞毒性。动物成像实验证明该纳米成像探针可实现活体层次高信噪比的小动物全身成像和前哨淋巴结的指示。     

溶胶-凝胶法制备有机/无机杂化材料工艺及其应用

介绍了溶胶–凝胶法制备有机/无机杂化材料的原理和基本过程,杂化材料的制备方法及对材料性能的影响,概述了杂化材料在结构材料、光学材料及其它材料中的应用研究。     

二氧化硅-共聚物杂化荧光纳米材料用于动物活体成像

以氧化硅(SiO_2)前驱体与三嵌段共聚物F108合成较小粒径的SiO_2-共聚物杂化纳米体系(SNP),并与高效近红外发射的疏水染料M507自组装,构建了近红外发光纳米探针M507@SNP。同时,研究了M507@SNP的光物理性能和细胞毒性。动物成像实验证明该纳米成像探针可实现活体层次高信噪比的小动物全身成像和前哨淋巴结的指示。     

制备有机-无机杂化纳米材料的研究进展

有机-无机杂化纳米材料由于小尺寸和兼具有机、无机材料的各种优良性质,在许多领域都有巨大的应用潜质。本文介绍了模板法、嵌段聚合物自组装、含特殊官能团的乙烯基单体直接聚合法等制备纳米有机-无机杂化材料的方法,并对各自的特点进行了说明。     

Preparation of thick silica films in the presence of poly(acrylic acid) by using electrophoretic sol-gel deposition

Thick silica films were fabricated by electrophoretic sol-gel deposition of silica particles on a stainless steel sheet. Using sols prepared by the sol-gel method with poly(acrylic acid) (PAA) films of ca. 25 m in thickness were prepared with no cracks. The films were shown to be agglomerates of monodispersed silica particles with PAA. The size of the silica particles decreased with an increase in the added amount of PAA. The deposited weight was considerably larger for the films with PAA than that of the films without PAA.     

Preparation of nonwoven polyimide/silica hybrid nanofiberous fabrics by combining electrospinning and controlled in situ sol-gel techniques

A controlled in situ sol-gel synthesis combined with the electrospinning technique and postspun imidization was applied in the fabrication of polyimide/silica hybrid nonwoven nanofiberous fabrics with excellent thermal and mechanical performance. The nanofiberous fabrics were prepared by electrospinning of the solution of tetraethoxysilane (TEOS) and polyamic acid (PAA). The different silica contents in the fabrics were achieved by varying the amount of TEOS while fitting the solid content of PAA. The final polyimide/silica fabrics was obtained after imidization of PAA and gelation of silica phase simultaneously accomplished through a step-wise heating process. Some specific IR techniques and other characterizations indicated the successful incorporation of the silicon dioxide (SiO₂) into the PI matrix and the relatively even distribution of the SiO₂ in the fabrics. An increase of 133 °C in the decomposition temperature and 4-fold enhancement of the ultimate tensile strength were achieved for the hybrids with a 6.58 wt.% of SiO₂ content, compared to the pure PI fabric. The excellent performance could be attributed to the good compatibility between the polyimide and silica, and good adhesion among the fibers, which resulted from the controlled TEOS hydrolysis and the simultaneous imidization and gelation process.     

Synthesis of mesoporous silica materials with ascorbic acid as template via sol-gel process

Mesoporous silica materials with pore diameters of 2-5 nm have been prepared using ascorbic acid as a nonsurfactant template or pore-forming agent in HCl-catalyzed sol-gel reactions of tetraethylorthosilicate,followed by removing the ascorbic acid compound by extraction with ethanol.Characterization results from nitrogen sorption isotherm,powder X-ray diffraction and transmission electron microscopy indicate that the materials have large specific surface areas (e.g.1000 m2/g) and pore volumes (e.g.0.8 cm3/g).The rnesoporosity is arisen from interconnecting disordered wormlike channels and pores with relatively broad size distributions.As the ascorbic acid concentration is increased,the pore diameters and pore volumes of the materials increase.     

Elaboration of silica colloid/polymer hybrid support for oligonucleotide synthesis

One way to increase the sensitivity of DNA diagnostic assays developed on microarrays is to improve the solid phase that allows the extraction of the target from a biological sample, before detection. Two parameters are influencing the performances of this capture step: (i) the specific surface area being offered for the capture and (ii) the number and the accessibility of oligonucleotide probes immobilized on the surface. In this context, we have developed an attractive approach which fulfills these two points. Our strategy was to elaborate a new material of high specific surface area, suitable to serve as support for both solid-phase oligonucleotide synthesis and in vitro diagnostic assay. This material has consisted of aggregates of colloidal amino-silica nanoparticles covalently linked by poly(ethylene oxide) (PEO) arms. The aggregation of amino-silica particles in the presence of reactive bis-isocyanate PEO was achieved in a controlled manner. The aggregate size and structure were examined by microscopy. The specific surface area of this material was measured by nitrogen adsorption technique. The composition of aggregate was studied by thermogravimetry and X-ray photoelectron spectroscopy. Then, this material has been successfully used as support for oligonucleotide synthesis of high yield and purity. The resulting system will be further evaluated in a diagnostic assay on a microarray.     

PEO掺杂氧化镍薄膜的溶胶-凝胶法制备及电致变色性能研究

以无水醋酸镍、乙醇为前驱液, 加入适量正丁醇及PEO2000等为稳定剂, 采用改进的溶胶-凝胶法制备了稳定的PEO2000纳米Ni(OH)₂复合溶胶体系, 采用旋涂法在ITO (In₂O₃∶Sn)导电玻璃上形成均匀的氧化镍薄膜. 研究了溶胶组分对成膜性能的影响, 采用TG-DSC分析、X射线衍射仪和扫描电镜, 研究了热处理过程中的结构变化和表面形貌. 循环伏安和可见光透过率测试表明该氧化镍薄膜具有良好的电致变色性能和阳极着色效应.     

Auto-organisation of hybrid organic-inorganic materials prepared by sol-gel process

Silica-based hybrid organic-inorganic materials prepared by sol-gel chemistry exhibit chemical and physical properties revealing their anisotropic organisation. Besides the opportunities that this phenomenon opens for the preparation of new materials, it also provides arguments to the chemist looking for a better comprehension and control of the organisation of solids.     

Preparation of well-defined polystyrene/silica hybrid nanoparticles by ATRP

Immobilization of the atom transfer radical polymerization (ATRP) macroinitiators at the silica nanoparticle surfaces was achieved through surface modification with excess toluene-2,4-diisocynate (TDI), after which the residual isocyanate groups were converted into ATRP macroinitiators. Structurally well-defined polystyrene chains were grown from the nanoparticle surfaces to yield individual particles composed of a silica core and a well-defined, densely grafted outer polystyrene by ATRP, which was initiated by the as-synthesized silica-based macroinitiator. FTIR, NMR and gel permeation chro-matography (GPC) were used to characterize the polystyrene/silica hybrid particles.     

Thickness of a silica-tethered poly(ethylene oxide) layer measured by spin labeling

EPR spectroscopy of labeled poly(ethylene oxide) (PEO) grafted on silica has been used to characterize the conformation and local dynamics of the chains. Grafted molecules of MW 2000 with grafting ratios of 0.045, 0.057, 0.126, and 0.42 molecules/nm² were in contact with benzene. The mobility of the label was compared with that observed for solution of PEO from very diluted to highly concentrated and even bulk PEO. Thus, the concentration inside the grafted layer could be evaluated and also the thickness, which evolves rather linearly with the grafting ratio. © 1995 John Wiley & Sons, Inc.     

Thermoresponsive properties of porous poly(N‐isopropylacrylamide) hydrogels prepared in the presence of nanosized silica particles and subsequent acid treatment

Porous poly(N‐isopropylacrylamide) hydrogels were prepared by the free‐radical polymerization of its monomer and a suitable crosslinker in the presence of spherical silica particles of different sizes (74 and 1600 nm) and by the subsequent acid extraction of silica. The yields were 81–83%, and the yields were not affected by the silica content. Scanning electron microscopy observations revealed the porous structure of the hydrogels. Porous and nonporous hydrogels showed volume phase transitions from swelling states to deswelling states at approximately 30 °C, as analyzed by the ratio of the diameter of cylinder‐shaped hydrogels to that of the glass tube used for the hydrogel preparation at the corresponding temperature. Deswelling, which was analyzed by rapid changes in the temperature of the aqueous media from 20 to 40 °C, was facilitated by decreased silica particle size and increased silica content. The deswelling rate constant of the hydrogel prepared with 74‐nm silica at 10 v/v % (silica/solvent) was more than 1500 times greater than that of conventional hydrogels. Swelling was similarly analyzed through changes in the temperature from 40 to 20 °C and was independent of the pore structure. The deswelling–swelling cycle was repeatable with reasonable reproducibility. Moreover, the mechanical strength of the porous hydrogels was significantly maintained compared with that of conventional nonporous hydrogels. This method produced thermoresponsive hydrogels of suitable mechanical strength and remarkable deswelling properties. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 4228–4235, 2002