Physical Chemistry, Lund University, P.O. Box 124, Lund, SE-221 00, Sweden.
Phys Chem Chem Phys. 2010 Apr 21;12(15):3852-8. doi: 10.1039/b923364d. Epub 2010 Feb 26.
Plate-like particles of SBA-15 form from smaller units (primary particles) that aggregate in an oriented manner. In this report we influence this aggregation by adding salt to the ongoing synthesis, generating well-ordered hexagonal p6m structure (SBA-15), with varying particle diameters. The additions, with either NaCl or NaI, were made at a time corresponding to the onset of oriented aggregation. Both salts promote the aggregation and particles with diameters of up to 5 microm were obtained. The thickness, about 0.4 microm, of the particles was retained, in accordance with the proposed growth mechanism. The aggregation characteristic was dependent on the salt used and the concentration of the salt. Both the cation and the anion were found to influence the aggregation. Having salt present already at the start of the synthesis gave a different product. The particle formation process depends on an interplay between attractive and repulsive forces between aggregates. We interpret the observed effect of salt addition to a medium which already has a very high ionic strength (1.6 M HCl) as due to ion binding to the combined polyethylene oxide-silica brush at the particles surface.
SBA-15 的板状颗粒由较小的单元（初级颗粒）聚集而成，这些初级颗粒以定向的方式聚集。在本报告中，我们通过在持续的合成中添加盐来影响这种聚集，生成具有不同粒径的有序六方 p6m 结构（SBA-15）。添加的盐为 NaCl 或 NaI，其添加时间与定向聚集的开始时间相对应。两种盐都促进了聚集，得到了直径达 5 微米的颗粒。根据提出的生长机制，保留了约 0.4 微米厚的颗粒。聚集特性取决于所用的盐和盐的浓度。阳离子和阴离子都被发现对聚集有影响。在合成开始时就存在盐会得到不同的产物。颗粒形成过程取决于团聚体之间吸引力和排斥力的相互作用。我们将在已经具有非常高离子强度（1.6 M HCl）的介质中添加盐的观察到的效果解释为离子与颗粒表面的聚氧化乙烯-硅刷的结合。
