采用耗散粒子动力学(DPD)方法研究了嵌段共聚物EO20PO70EO20(P123)在水、乙醇/水溶液及二氧化硅溶胶体系中的相分离行为.不同质量分数的P123在水溶液中共形成4种相分离状态:球状胶束(10%);椭球胶束(20%)、棒状胶束(30%)和三维立方胶束(50%).在模板剂质量分数为10%的乙醇/水溶液中,模板剂胶束稳定性随着乙醇含量的增加而变差.在二氧化硅溶胶体系中,模板剂质量分数低于5%时无胶束形成;模板剂质量分数增至10%时,P123发生相分离形成三维球状胶束;随着模板剂质量分数的进一步增加,模板剂分子夹含着水分子形成三维椭球状结构(20%)、三维立方结构(40%)和层状结构(60%).模拟结果与实验结果一致,说明DPD模拟可以从计算角度推测模板剂对介孔材料结构的影响.
Mesoporous materials were synthesized by template possess regular channel structure,narrow pore size distribution and high surface area,which are greatly related to the self-assembly of template. In order to investigate the template aggregates in the preparation process of mesoporous materials,dissipative particle dynamics( DPD) was adopted to simulate phase behaviors of EO20PO70EO20( P123) in water,ethanol/water solutions and silica sol. In the aqueous solution,P123 formed different morphologies at different mass fractions and four aggregation types were observed: spherical micelle( 10% P123) ,ellipsoid micelle( 20% P123) ,cylindrical micelle( 30% P123) and 3D-cubic phase( 50% P123) . In the ethanol/water system,the stability of template micelles decreased with the increasing of ethanol concentration. In the silica sol,the micelle did not form when the mass fraction of P123 was less than 5% ; the 3D spherical structure was observed when the mass fraction of P123 increased to 10% ; and the 3D ellipsoid structure( 20% ) ,3D-cubic phase( 40% ) and lamellar phase( 60% ) formed with the increasing of P123 mass fraction. Simulation results obtained in this work consisted with the experimental data reported in the literatures,which indicated that DPD simulation method can be used to study the influence of template on the structure of mesoporous material and guide the preparation of mesoporous material.