A general method to coat colloidal particles with silica
A general method to coat colloidal particles with silica
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DOI：
10.1021/la0347859
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发表时间：
2003-08-19
期刊：
影响因子：
3.9
通讯作者：
van Blaaderen, A
中科院分区：
文献类型：
--
作者：
Graf, C;Vossen, DLJ;van Blaaderen, A
描述了用二氧化硅涂覆胶体的一般方法。将两亲性非离子聚合物聚乙烯吡啶酮（PVP）吸附在各种胶体颗粒上，如小金胶体、金壳硅芯颗粒、大小银胶体、薄水铝石棒、三水铝石薄片和带正电或负电的聚苯乙烯。经过这种功能化后，稳定的颗粒可以转移到乙醇中的氨溶液中，并在种子生长过程中通过添加四乙氧基硅烷直接包裹在光滑均匀的变厚度硅壳上。所使用的聚合物的长度对胶体的稳定性和初始二氧化硅涂层的均匀性和光滑度有很大影响。这种方法对于不能通过stober样生长过程直接被SiO2覆盖的胶体颗粒特别有用。与文献中已知的涂覆此类颗粒的方法相比，这种新方法更快，既不需要使用硅烷偶联剂，也不需要用硅酸钠预涂，这一步骤的可重复性很差。
A general method to coat colloids with silica is described. The amphiphilic, nonionic polymer poly(vinylpyrrolidone) (PVP) was adsorbed to various colloidal particles such as small gold colloids, gold-shell silica-core particles, small and large silver colloids, boehmite rods, gibbsite platelets, and positively or negatively charged polystyrene. After this functionalization the stabilized particles could be transferred to a solution of ammonia in ethanol and directly coated with smooth and homogeneous silica shells of variable thickness by addition of tetraethoxysilane in a seeded growth process. The length of the polymer used strongly influences the stability of the colloids and the homogeneity and smoothness of the initial silica coating. This method is especially useful for colloidal particles that cannot be covered directly with SiO2 by a Stober-like growth process. Compared to methods known from the literature for the coating of such particles, this new method is faster and requires neither the use of silane coupling agents nor a precoating step with sodium silicate, which is poorly reproducible.