二氧化硅微球的制备与形成机理

在酯-醇-水-碱体系中以正硅酸乙酯为硅源、氨水为催化剂、乙醇为溶剂,采用改进的溶胶-凝胶法合成了二氧化硅球形颗粒。采用红外光谱、BET吸附曲线、扫描电镜等手段重点研究了正硅酸乙酯加料方式对二氧化硅粒径和形貌的影响。分析表明,采用正硅酸乙酯分步滴定法能提高二氧化硅微球的球形度、窄分布、单分散与致密性。同时,在反应温度25℃、正硅酸乙酯浓度0.12mol/L、氨浓度为15.0mol/L、去离子水浓度0.90mol/L、无水乙醇浓度2.35mol/L、pH值为9～12的条件下,获得了直径约200～250nm、粒径一致性约为0.5、分布偏差约为7.5%的球形二氧化硅单分散颗粒;研究和讨论了二氧化硅微球的形成机理。     

微米二氧化硅微球的制备研究进展

以聚合诱导胶体凝聚法、种子生长法、模板法和反相乳液法等制备方法为主线,综述制备微米二氧化硅微球的最新研究进展,同时以所得微球的性能为考察重点,对各种方法进行评价与展望;提出通过硅酸钠等低成本硅原料取代硅酸酯制备高性能硅微球是未来研究重点;改变种子生长法中溶剂的种类、制备粒径更大的单分散微球并进行理论探究成为种子生长法的研究方向;采用模板法对聚合诱导胶体凝聚法制备的微球孔结构进行重组完善,得到纯度较高、机械强度和比表面积较大的微米有序介孔二氧化硅微球,进而用于高性能色谱柱的制备以及生物催化等领域,发展前景可观。     

两步法制备二氧化硅微球的影响因素

采用两步法合成的SiO2微球.发现氨水作为催化剂使用量过少时,SiO2微球的表面会不光滑,甚至微球的形状不规则.SiO2微球的大小主要由TEOS的初始用量和二次用量之比决定,给出了SiO2质量百分比和体积比的测量方法.     

二氧化硅/壳聚糖复合微球的制备及性能

通过溶胶-凝胶法制备出3种不同粒径的SiO₂微球,利用扫描电镜分析了微球的粒径分布情况,SiO₂微球粒径分别在140nm、208nm、336nm左右,在一定范围内,硅球的粒径随正硅酸四乙酯(TEOS)/氨水的添加量增加而增大。选取粒径在336nm左右的SiO₂微球,使用硅烷偶联剂3-(2,3-环氧丙氧基)丙基三甲氧基硅烷(GPTMS)将壳聚糖(CS)接枝在SiO₂微球上,得到SiO₂@CS复合微球。通过红外光谱分析、X射线衍射等对微球进行了表征。接枝CS后对SiO₂微球的结晶特性没有影响,微球仍为无定形晶体。元素分析结果表明CS的接枝量为1.03%。使用振荡法进行抗菌测试,SiO₂@CS复合微球对金黄色葡萄球菌(S.aureus)和大肠杆菌(E.coil)的抑菌率分别为85.52%和47.14%,表明复合微球有一定的抗菌效果。     

SiO2微球的制备与应用

综述了致密和多孔SiO2微球的制备方法．重点描述了近年来SiO2微球的一些新应用。     

中空介孔二氧化硅微球的制备及研究进展

中空介孔二氧化硅微球具有较大的中空空腔、可控外层介孔结构、大比表面积、良好的生物相容性等特性,因而被广泛应用于药物储存与释放、纳米反应器、催化、吸附等领域。对中空介孔二氧化硅微球的制备方法进行介绍,综述和评价了模板法、选择性刻蚀法、喷雾干燥法等三类制备方法的研究进展及其优缺点,并对其应用前景进行了展望。     

微乳液法制备纳米二氧化硅

研究了在TritoX-10-正辛醇-环己烷-氨水所组成的微乳液体系下,制备纳米二氧化硅的实验方法.并对制备的纳米二氧化硅形貌进行透射电镜分析,结果显示,制备的纳米二氧化硅为均匀球形颗粒,粒径80nm左右.     

单分散纳米二氧化硅微球的制备及羧基化改性

采用改进工艺条件的Stober法制备纳米SiO_2微球.用场发射扫描电镜(FESEM)分析了纳米二氧化硅的形貌、粒径.结果表明,通过温度梯度法和控制氨水浓度变化制备出高圆度、单分散、粒径可控的纳米级二氧化硅微球.用KH-550硅烷偶联剂和丁二酸酐对纳米二氧化硅表面羧基化改性.采用X射线能谱仪(EDS)、热重(TGA)、傅里叶红外(FTIR)等手段对改性后纳米二氧化硅的结构、元素种类及含量进行了表征.结果表明,纳米二氧化硅表面成功接枝了羧基官能团.     

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。     

表面修饰二氧化硅微球的制备、表征及分散性能

采用一步法制备了亚微米纯二氧化硅微球及8种有机硅表面修饰的二氧化硅微球,用扫描电镜、氮吸附、零电荷点测定等方法对微球进行了表征,对比研究了微球在不同介质中的分散性能。所有微球都呈球形,形貌较好,依表面修饰基团的不同,粒子直径在0.42~0.54nm之间。所有微球均为实心,比表面积均小于21m2/g。微球的零电荷点在8.25~8.93之间变化。粒子经过表面修饰后,在不同介质中表现出了不同的分散行为,微球的分散行为可以由微球的亲水及疏水性,以及DLVO理论得到基本解释。     

Synthesis of ZnS nanoparticles into the pore of mesoporous silica spheres

The ZnS nanoparticles were exclusively synthesized in the pores of the mesoporous silica (MS) particles which had been coated with two bilayers of poly(allylamine hydrochloride) (PAH)/poly(styrene sulfonate) (PSS) via the layer-by-layer (LbL) self-assembly technique. Measurements and analysis of XRD and TEM showed that the ZnS nanocrystals were inserted into the pores of the MS spheres. This approach can be used to prepare composite materials involving functional inorganic nanoparticles which have potential application in biological immunoassay and photoelectronic fields.     

新型多级形貌的硅酸盐空心球的合成

由化学方法制备的氧化硅通常是在较苛刻的条件下制备的,如升高的温度、较高压力和/或强酸性、强碱性媒介,相比之下,在自然界里具有精致形貌的硅藻氧化硅构架在温和周围环境下的水相中就可以形成.本文中我们系统研究了具有相似于硅藻多级形貌的氧化硅空心球的合成,该合成经过一步步骤,采用嵌段高分子EO76PO29EO76基的乳液和廉价硅酸钠溶液为硅源.     

Drug delivery devices based on macroporous silica spheres

A new kind of silica materials was proposed as carriers for drug delivery. The materials are characterized by the presence of hierarchical macro/mesopores, penetrable macropores and large pore volumes. The unique structure renders them ideal carriers for efficient and sufficient loading of drugs to establish controlled delivery systems. A series of such materials were synthesized and derivatized with octyl or octadecyl to investigate their drug delivery behavior. Nimodipine, as a model drug, was entrapped into the carriers by repeated soaking, filtration and evaporation. It is found that the drug-loading amount increased with increasing mesopore sizes of the carriers. The loading amount can reach as high as 350 wt% (drug/carrier). The in vitro release studies demonstrate that both enhanced release and sustained release can be achieved on the proposed materials. Moreover, the release speed can be controlled by the macropore sizes and surface characteristics of the materials.     

Phosphonic acid-functionalized hollow silica spheres by nitroxide mediated polymerization

A new strategy to prepare phosphonic acid-functionalized hollow silica spheres is proposed via nitroxide mediated polymerization of diisopropyl p-vinylbenzyl phosphonate on the surface of hollow silica spheres (HSSs) and hydrolysis thereafter. The thickness of the organic layer of PVBPA can be controlled by the quantity of the monomers. The structure and morphology of poly(vinylbenzyl phosphonic acid) (PVBPA) grafted HSSs (HPSSs) are confirmed by FTIR and TEM. The addition of HPSS in PVBPA membranes can improve the water retentivity of the composite membranes. The composite membranes with HPSSs exhibit higher water uptake and proton conductivity than the pure PVBPA membranes.     

纳米二氧化钛/硅胶光催化剂的制备与性能研究

采用溶胶 凝胶法在硅胶载体上制备了纳米二氧化钛 ,研究载体表面负载二氧化钛的结构、表面形态及其光催化性能。实验发现 ,包覆在硅胶表面的二氧化钛大小为 2 0～ 30nm ,且分布均匀 ,晶型为锐钛矿相 ,以甲基橙作为降解对象研究所制备样品的光催化性能。     

Synthesis of hollow silica spheres SBA-16 with large-pore diameter

Hollow silica SBA-16 spheres with cubic ordered mesoporous shells were synthesized by an emulsion-templating method, using Pluronic F127 as a structure-directing agent, tetraethyl orthosilicateas as a silica source and heptane as a cosolvent in the presence of NH₄F. The size of these spheres is in the range of 10 to 30 μm. The shell is about 700 nm thick and consists of large pores, ~ 9 nm in diameter, arranged in a cubic order. After calcination, the spheres maintain their mesoporosity and show a high surface area of 822 m²/g. The formation mechanism of the silica hollow spheres is discussed.     

Monodisperse hollow silica spheres: An in-depth scattering analysis

Herein, we fabricate hollow silica nanoparticles with exceptionally narrow size distributions that inherently possess two distinct length scales—tens of nanometers with regards to the shell thickness, and hundreds of nanometers in regards to the total diameter. We characterize these structures using dynamic and static light scattering (DLS and SLS), small angle X-ray scattering (SAXS), and transmission electron microscopy (TEM), and we demonstrate quantitative agreement among all methods. The ratio between the radius of gyration (SLS) and hydrodynamic radius (DLS) in these particles equals almost unity, corresponding to ideal capsule behavior. We are able to resolve up to 20 diffraction orders of the hollow sphere form factor in SAXS, indicating a narrow size distribution. Data from light and X-ray scattering can be combined to a master curve covering a q-range of four orders of magnitude assessing all hierarchical length scales of the form factor. The measured SLS intensity profiles noticeably change when the scattering contrast between the interior and exterior is altered, whereas the SAXS intensity profiles do not show any significant change. Tight control of the aforementioned length scales in one simple and robust colloidal building block renders these particles suitable as future calibration standards.

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一种用于长寿命水系锌锰电池的海藻酸钠/二氧化硅准凝胶复合电解质

锌锰(Zn-MnO₂)电池具有高安全性、高环保性、高性价比的优点, 适用于大规模储能电池。然而, 金属锌负极在充放电中会因为“尖端效应”而产生锌枝晶, 造成电池容量衰减甚至短路失效。本研究通过添加亲水性纳米二氧化硅(SiO₂)和海藻酸钠(SA)将电解质转化为准凝胶电解质, 有效抑制了锌负极表面的枝晶生长, 以及由之造成的Zn-MnO₂电池性能衰减。恒流充放电测试结果表明, 采用准凝胶电解质的Zn-MnO₂电池在1800次循环后容量保留率可达78%, 而使用普通电解质的Zn-MnO₂电池在1000次循环后容量已基本衰减为0。进一步探究准凝胶电解质对锌沉积行为的影响, 发现准凝胶电解质的三维网络结构可以提高锌离子分布的均匀性, 降低电池容量衰减速度与失效风险。     

A facile method to fabricate a series of micrometer scale hollow silica spheres

Hollow silica spheres (HSS) with the controllable diameters of 1.0 to 5.0 μm were successfully synthesized by adjusting the initial doubly distilled water volume in mixed ethanol-water solvent based on a complex approach that dispersion polymerization coexisted with a sol-gel process. The size of the HSS was uniform and the surface of the shell was smooth as observed by SEM. The FT-IR spectrum indicated that the inside core was completely removed. The thermal property and the compositions of core-shell spheres were investigated by TG-DSC.