两性杂双子表面活性剂在水溶液中的自组装行为:耗散粒子动力学模拟

Self-assembly behaviors of zwitterionic heterogemini surfactant in aqueous solution: a dissipative particle dynamics simulation

利用耗散粒子动力学(dissipative particle dynamics, DPD)方法对CmH2m+1-PO4--(CH2)2-N+(CH3)2-Cn H2n+1 (简记为Cm-P-N-Cn,其中m, n=9, 9; 9, 12; 9, 15; 9, 18; 12,12; 12, 15; 12, 18; 15, 15; 15, 18; 18, 18)型系列两性杂双子表面活性剂在水溶液中的自组装行为开展了模拟研究,观察到了球状、柱状、平面网格、层状、蜂窝状,以及一维孔道、二维孔道和三维孔道等多种自组装结构的形成.所有模拟体系均随表面活性剂浓度的逐步升高而呈现出"球状—柱状—平面网格—三维孔道—层状—二维孔道—一维孔道"的结构转化规律.当m=n时,疏水链长度对于自组装行为有显著影响.此外, Cm-P-N-Cn分子内部各功能基团与水分子间的相互作用强弱和亲近程度可通过径向分布函数来完全体现.研究结果可为两性杂双子表面活性剂自组装行为的进一步研究及其实际应用提供新的见解.

Self-assembly behaviors of a series of zwitterionic heterogemini surfactants CmH2m+1-PO4--(CH2)2-N+(CH3)2-CnH2n+1,abbreviated as Cm-P-N-Cn(m,n=9,9;9,12;9,15;9,18;12,12;12,15;12,18;15,15;15,18and18,18),have been investigated in aqueous solution with a dissipative particle dynamics(DPD)method.Morphologies such as sphere(S),rod(R),planar grid(PG),lamella(L),honeycomb(H),one-,two-and threedimensional tunnels(1DT,2DT and3DT)have been observed.With increase of surfactant concentration in the aqueous solution,a distinct transition path S-R-PG-3DT-L-2DT-1DT is shown to be common for all simulated systems.Besides,the hydrophobic chain length has a significant influence on the self-assembly behaviors when m≠n.Radialdistribution function is an effective method for quantitative evaluation of interaction andrelationship between each functional group in the Cm-P-N-Cn molecule and water.Theresults provide an insight into self-assembly behaviors of zwitterionic heterogemini surfactantsand corresponding applications.