三维有序大孔SnO2及SnO2/SiO2材料的制备及结构特征

以SnCl2-2H2O和正硅酸乙酯为原料，用微球直径为585nm的聚苯乙烯胶晶为模板，制备了三维有序大孔SnO2和SnO2／SiO2材料，SEM观察表明，直接用SnCl2的乙醇溶液为前驱物溶液，难以形成有序的大孔结构，加入正硅酸乙酯或将SnCl2溶液转变为氧化物溶胶，则得到的大孔材料孔结构三维有序排列相当好，孔径为453～500nm，孔与孔之间通过小孔相连，XRD分析表明，大孔材料孔壁由晶粒直径约为17nmSnO2粒子构成。     

十二胺用量对正硅酸乙酯水解缩聚反应及其产物的影响

利用正硅酸乙酯为硅源,十二胺作为模板剂和催化剂,通过溶胶-凝胶法合成多孔SiO2微球,着重研究十二胺用量对正硅酸乙酯水解缩聚反应的速度及产物形貌和孔参数的影响。采用扫描电子显微镜、N2等温吸附、热重分析及小角度X射线衍射分析等对合成的多孔SiO2微球进行表征。结果表明:所有微球都具有双模微孔,随着十二胺用量的增加,合成的多孔SiO2微球的颗粒尺寸减小,比表面积减小,而孔的有序性提高。     

单因素对单分散二氧化硅微球制备的影响

以氨水为催化剂、正硅酸乙酯为硅源、醇为溶剂,采用改进的溶胶-凝胶工艺制备单分散SiO2微球,通过扫描电镜、激光粒度分析仪着重研究了正硅酸乙酯添加方式、反应温度、溶剂类型等单因素对SiO2的颗粒大小和形貌的影响.结果表明,正硅酸水解对醇溶剂是有选择性的,乙醇作为溶剂合成SiO2的单分散性和球形度最好.连续滴定和分步滴定更有利于单分散SiO2微球的形成.水解温度升高,生成的颗粒粒径将运渐增大,最佳反应温度为常温25℃或恒温水浴25～35℃.     

双介孔SiO2的制备及表征

以正硅酸乙酯(TEOS)为硅源,十六烷基三甲基溴化铵(CTAB)为模板剂,采用溶胶-凝胶法制备了具有双介孔独立分布的SiO2,并用FT-IR、HRTEM、BET等方法对SiO2进行了表征.结果表明,双介孔SiO2中存在大量无序排列的2～3nm的小介孔和18nm左右的大介孔,具有高比表面积(716.4～968.6m2/g)和大孔(1.03～1.63mL/g):通过改变氨水及模板剂的用量可以实现对孔分布的调控.     

单分散球形介孔SiO_2的合成与表征

以十六烷基三甲基氯化铵(CTAC)为模板剂,正硅酸乙酯(TEOS)为硅源,甲醇为共溶剂,氢氧化钠为催化剂,采用水热法制备出不同粒径、单一分散、高度有序的介孔SiO2微球,并利用扫描电子显微镜(SEM)对所制备的微球进行表征。考察了体系中CTAC浓度、TEOS浓度、甲醇的比率和温度等条件对所制备的SiO2微球的粒径及分散性的影响。同时采用XRD、BET、HRTEM等手段对样品进行分析表征。结果表明合成的单分散球形SiO2具有有序的六方相介孔结构,并且具有较高的比表面积。     

正硅酸乙酯水解SiO_2改性酚醛泡沫的制备与表征

通过正硅酸乙酯在碱性条件下水解生成的SiO2粒子改性酚醛泡沫。利用SEM和TEM对泡沫体进行了观察,同时测试了不同正硅酸乙酯添加量对泡沫冲击强度和压缩强度的影响,并通过热失重分析了改性酚醛泡沫的热稳定性。结果表明:正硅酸乙酯水解生成的SiO2和泡沫体有良好的亲和性,大部分SiO2晶粒尺寸在1μm左右,当正硅酸乙酯的添加量为2%时,泡沫有较好的压缩强度和冲击强度,比纯酚醛泡沫分别提高了40%和63%。同时泡沫的热稳定性有了一定的提升。     

气-液界面非担载SiO2无机膜的仿生制备

利用有机大分子CTAB的自组装体为模板来调制正硅酸乙酯（TEOS）的水解缩聚，于气－液界面上制备出非担载SiO2无机膜，对了膜时间进行了选择，考察了仿生制备SiO2膜过程中物料配比对成膜质量的影响，对其进行了优化，由CTAB极性头基排列而成的六边形区域聚集于溶液表面，TEOS在其内部的水解缩聚及随后的层层复制过程形成了仿生合成膜的空间网络结构。     

SiO2包覆纳米SiC的制备及表征

采用正硅酸乙酯水解法在SiC表面包覆SiO2,并通过实验探讨了TEOS用量、总体系CTEOS等因素对包覆效果影响。实验确定了制备包覆粒子的优化工艺条件：SiC／TEOS的最佳物质量比值为5：1,最佳总体系CTEOS为0．2mol／L。采用ZETA、IR、XRD等测试手段对SiO2改性的碳化硅粉体进行了表征。沉降实验表明：碳化硅表面改性后,在硅溶胶中浆料的稳定悬浮性提高。     

γ-Fe2O3/SiO2纳米复合粉体的制备

以硝酸铁和正硅酸乙酯分别作为氧化铁和SiO2的前驱体,通过溶胶-凝胶工艺制备了γ-Fe2O3/SiO2纳米复合粉体.若使用氯化铁为氧化铁前驱体,SiO2基体中则会生成α-Fe2O3.当干凝胶热处理温度较低时(T＜400℃),复合粉体(硝酸铁为前驱体)以非晶态存在.当T达到600℃时,γ-Fe2O3粒子在SiO2基体中大量形成.随着热处理温度的进一步升高,粉体中开始有α-Fe2Oa杂质生成.使用盐酸做添加剂对复合粉体中γ-Fe2O3粒子大小及颗粒尺寸分布均有显著影响.     

纳米二氧化硅的制备研究

采用溶胶-凝胶法制备纳米SiO2,以正硅酸乙酯为原料，氯化铵为催化剂，以乙醇水溶液为溶剂，制备SiO2超细粉体，还对影响生成的原料浓度、pH值、反应温度、反应时间及焙烧温度对产物的影响进行了研究，找到了最佳的反应条件。通过控制参数，可使沉淀的后续处理简化、时间缩短。该法制得的SiO2粉体颗粒均匀，平均粒径为63．5nm左右。     

Elaboration of hybrid organic–inorganic materials for ammonium ions retention: Electron microscopy bipolarized observations and Xe solid-state NMR

Translucent organic–inorganic hybrid porous silica materials have been prepared via the acid-catalysed hydrolysis and condensation of TEOS and various p-sulphonatocalix[n]arene derivatives. Xerogels and aerogels have been prepared. The morphology of the gels was characterized by electron microscopy (SEM and ESEM) and by hyperpolarized ¹²⁹Xe NMR. The aerogels showed a porous structure not influenced by the size of the calixarene derivative incorporated in the gel. The efficiency of these new materials towards the retention of ammonium ions was discussed.     

Synthesis and characterization of silica microcapsules using a sustainable solvent system template

We report direct encapsulation of a sustainable solvent system in silica microcapsules via a sol-gel reaction of silica precursor for potential application of thermoplastic self healing polymeric system. The silica microcapsules were realized by hydrolysis and condensation of tetraethyl orthosilicate (TEOS) using aqueous glycerol microemulsion as template. The pre-hydrolysis of TEOS was found to be useful to obtain isolated free flowing silica microcapsules. Furthermore, the effects of different parameters viz. temperature, rotor speed, the solvent/TEOS ratio on the synthesis of silica microcapsules are studied. A novel micro compression technique to study mechanical properties of the silica microcapsules is reported. The silica microcapsules reported were found to have better mechanical properties compared to incumbent Urea-Formaldehyde (UF) based organic microcapsules.     

正交设计在单分散球形SiO2制备中的研究

用正交试验,采用L9 (33)正交表,在醇水体系中采用氨作催化剂,正硅酸乙酯为硅源,研究了各原料浓度对单分散球形SiO2 粒度的影响。研究表明在其它条件不变的情况下,二氧化硅的粒度随着氨和水浓度的增加而明显增大,随TEOS 浓度的增加,二氧化硅的粒度也略有增大,但幅度较小。本文还详细研究了二氧化硅颗粒的形成机理。     

低折射率疏水SiO_2薄膜的制备和表征

为了制备低折射率疏水SiO_2薄膜,将正硅酸乙酯(TEOS)和二甲基二乙氧基硅烷(DDS)在碱性条件下共水解缩聚,再以六甲基二氮硅烷(HMDS)做进一步的改性,采用提拉浸渍工艺在玻璃基底上制备单层增透膜。通过对溶胶粘度随老化时间的变化规律及HMDS添加对薄膜接触角影响等的分析与研究,制备了接触角最大的低折射率薄膜;同时对薄膜的红外特性、透过率、折射率进行了表征。结果表明:TEOS和DDS共水解缩聚提高了膜层疏水性,经HMDS改性后,薄膜的接触角为149°,折射率为1.12。     

Fabrication of superparamagnetic hydroxyapatite with highly ordered three-dimensional pores

Hydroxyapatite (HA) with highly ordered three-dimensional pores, whose size is about 300 nm, was prepared by colloidal template method. The effect of the surface modification of silica spheres on the order degree of porous structure was investigated by field emission scanning electron microscopy (FESEM). Then, superparamagnetic Fe₃O₄ nanoparticles were fabricated via redox reaction, followed by coating with silica via a sol–gel process, in which a certain amount of TEOS was used in order to control the thickness of the silica shell. X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetometry were applied to characterize the properties. Finally, Fe₃O₄ magnetic nanoparticles coated with silica were adsorbed in the mesopores of HA with highly ordered three-dimensional pores by capillarity. The influence of dispersing agent on the adsorption results has been studied. Magnetometry was applied to characterize the magnetic properties of superparamagnetic HA. The quantities of adsorbed SiO₂/Fe₃O₄ nanoparticles with core–shell have been compared by variation of saturation magnetization before and after adsorption.     

Defect-sealing synthesis of vertically oriented ordered mesoporous silica membranes

Vertically oriented ordered mesoporous silica membranes have been successfully synthesized in our laboratory in the form of silica plugs filling the macron-sized straight pores of hydrophobic track-etched polycarbonate membrane support. However, these membranes have shown gaps between the plugs and support pore wall which make the membranes unfeasible for use. This paper reports on techniques of synthesis of defect-free ordered mesoporous silica membranes by filling the gaps with microporous silica. Here, the elimination of defects is achieved by filling the membrane gaps with an alkoxysilane followed by exposure to humid air to allow controlled hydrolysis and condensation resulting in the formation of microporous silica within the gaps. Molecular probing gas permeation and helium/nitrogen (or oxygen) binary separation tests, coupled with surface characterization methods, show that the final membranes contain ordered mesopores of about 2.7 nm pore diameter, running through the membrane, with gaps sealed by microporous silica having a pore size <0.55 nm.     

溶胶凝胶法制备具有介孔结构的聚酰亚胺/SiO_2多孔复合微球

采用反相乳液法,以水溶性聚酰胺酸三乙胺盐(PAAS)、正硅酸乙酯(TEOS)为前驱体,通过溶胶凝胶法制备了具有介孔结构的聚酰亚胺(PI)/SiO_2多孔复合微球。将PAAS水溶液和TEOS水解液的混合溶液在液体石蜡中形成反相乳液,TEOS经水解缩合形成无机三维骨架,通过化学酰亚胺化使复合体系中的PAAS转变为PI,成功制备了含有介孔结构的PI/SiO_2多孔复合微球。研究发现,随着SiO_2含量的增加,复合微球的规整性不断提高,其比表面积由20.5 m~2/g增加至521.8 m~2/g。同时发现,调节TEOS水解液的pH值,微球的比表面积也会发生相应的变化。此外,热重分析结果显示该复合微球的热分解温度超过500℃,表明其具有优异的热稳定性。     

加水量对水解法合成多孔二氧化硅微球的影响

为研究加水量对水解法合成多孔二氧化硅微球的影响,在十六烷基三甲基溴化铵-正硅酸乙酯-氨水-水体系中,在增加水用量的稀释条件下合成多孔二氧化硅微球,对微球的物质结构、形貌、孔结构等特性进行研究。结果表明:加水量还影响生成的多孔二氧化硅微球的大小、球形度、分散性及孔参数。反应体系未加水时,合成的二氧化硅微球的尺寸较小,球形度不高,比表面积和孔容均很小;增加水的用量对溶液稀释时,十六烷基三甲基溴化铵在水-醇溶液中形成胶束并作为模板,使正硅酸乙酯水解后在其上进行自组装,形成介孔二氧化硅微球。     

超细孔二氧化硅膜的制备研究

以正硅酸乙酯（ＴＥＯＳ）为原料，采用溶胶－凝胶技术在多孔陶瓷载体上制备出具有３．０ｎｍ孔径的ＳｉＯ２陶瓷膜。考察了制膜过程中ＴＥＯＳ、乙醇、水的相对量；酸碱催化和ｐＨ值；热处理温度及成膜助剂对膜性能的影响。在自制的单管膜分离器上，测定了Ｏ２、Ｎ２、ＣＯ２和ＣＨ４等气体在ＳｉＯ２陶瓷膜上的渗透性能。