Abstract:

Dissipative particle dynamics (DPD) method is performed to investigate the surfactant-silica cooperative organization effects in the mesoporous silica SBA-15 formation process, and steady shear is introduced to represent stirring in actual experiment.Simulation results show that uniform spherical super-molecular micelles can be assembled by the cooperation of the two precursors in SBA-15 formation, the template copolymer (P123) and the silica source (TEOS).The hydrophobic PPO micelle cores play a decisive role in the uniform mesopore formation process of SBA-15, while the hydrophilic PEO micelle coronas interact with the silica matrix to form the micropores upon calcinations.When steady shear introduced into the simulation system, the P123/TEOS super-molecular assembly no longer form spherical micelles, but form cylindrical micelles with hexagonally array, and finally form the structure of SBA-15.The simulation results proved that the DPD method can exactly describe the surfactant-silica cooperative organization and the SBA-15 mesophase formation process, which is also an effective tool for investigating the formation mechanism of ordered mesoporous silica.

Key words:

SBA-15, P123, 介观相, 耗散粒子动力学, 超分子自组装

摘要：

采用耗散粒子动力学方法（dissipative particle dynamics,DPD），以介孔分子筛SBA-15的合成原料P123/TEOS/H₂O为研究体系，模拟了P123/TEOS超分子自组装行为，及剪切力作用下介孔分子筛SBA-15六角介观相的形成过程。结果表明：在水溶液中，P123与TEOS两相能够发生协同作用自组装形成超分子聚集体（胶束），该胶束由疏水的PPO球核、亲水的PEO球壳以及聚集包裹在P123外部的TEOS组成;引入稳恒剪切力后，P123/TEOS超分子聚集体则会逐渐转变成规整的六角结构，并最终形成SBA-15六角介观相，这与实际材料的TEM电镜图片相吻合。可以说，DPD模拟方法是一个研究有序介孔分子筛SBA-15形成机理的有效手段，可为实验合成提供介观层面上的重要信息。此外，还拓展了DPD模拟在超分子自组装介观尺度研究方面的新应用。

关键词:

SBA-15, P123, 介观相, 耗散粒子动力学, 超分子自组装