Universitad Autonoma de Barcelona, Facultad de Medicina, Unidad de Biofisica-Cerdanyola del Valles, 08193, Spain.
Langmuir. 2011 Jun 7;27(11):7121-31. doi: 10.1021/la1043798. Epub 2011 May 6.
The influence of salts (NaCl, NaBr, and NaI) on the formation of mesoporous silica SBA-15 was studied in situ by small-angle X-ray scattering and diffraction. Pluronic P104 was used as structure director. The micellar properties and the dynamics of formation were clearly dependent on the presence of salt. It was also shown that the kinetics of mesophase formation, the initial value of the cell parameters, and the extent of long-range order were all influenced by salt additions. The observations are explained to primarily originate from the influence of the anions on the ethylene oxide part of the polymer, i.e., the corona region of the Pluronic micelles. Two effects are identified: a general ion effect causing dehydration of the ethylene oxide part and consequently inducing micellar growth, and a specific ion effect that counterbalances this. The study provides the basis for understanding the means by which addition of simple Na-salts influence the formation of mesoscopically ordered silicas synthesized using nonionic surfactants as structure directors, hence advancing the knowledge base toward a more rational design of mesoporous materials.
采用小角 X 射线散射和衍射法研究了盐（NaCl、NaBr 和 NaI）对介孔硅 SBA-15 形成的影响。使用 Pluronic P104 作为结构导向剂。胶束的性质和形成动力学明显依赖于盐的存在。还表明，介相形成的动力学、单元参数的初始值和长程有序度都受到盐添加的影响。这些观察结果主要归因于阴离子对聚合物中环氧乙烷部分的影响，即 Pluronic 胶束的冠区。确定了两种效应：一种是普遍的离子效应，导致环氧乙烷部分脱水，从而诱导胶束生长；另一种是特定的离子效应，它会抵消这种效应。该研究为理解添加简单的钠盐如何影响使用非离子表面活性剂作为结构导向剂合成的介观有序硅的形成提供了依据，从而为更合理地设计介孔材料提供了知识基础。
