NaSal/2SHNC对R14HTAB体系自组装行为的影响机制

Effecting mechanism of organic salts NaSal/2SHNC on self-assembly of cationic surfactant R14HTAB

采用粗粒化分子动力学(CGMD)模拟方法研究水杨酸钠(NaSal)和2-羟基萘-3-羧酸酯(2SHNC)两种有机盐对阳离子表面活性剂3-烷氧基-2-羟丙基三甲基卤化铵(R14HTAB)自组装过程及组装体性能的影响。结果表明:球型胶束的形成经历成核、团簇融合2个阶段;蠕虫状胶束的形成经历成核、团簇融合和胶束融合3个阶段;囊泡形成经历成核、团簇融合、胶束融合、盘状胶束和盘状胶束卷曲5个阶段;与NaSal相比,2SHNC在低浓度下即能促进胶束融合自组装形成蠕虫状胶束,且能促进复杂胶束囊泡的形成,表现出更强的促进胶束融合能力;2SHNC形成的蠕虫状胶束体系在非轴向拉伸过程中表现出更强的抗拉强度,2SHNC/R14HTAB体系形成的蠕虫状胶束更长,得到的体系黏弹性更好。

The self-assembly process and the mechanical property of 3-alkoxy-2-hydroxypropyltrimethylammonium halide(R14HTAB) modulated by two kinds of organic salts of sodium salicylate(NaSal) and 2-hydroxynaphthalene-3-carboxylate(2SHNC) were investigated through the coarse-grained molecular dynamics(CGMD) simulation.The results show that the formation of spherical micelles undergoes two stages: nucleation and cluster fusion. The formation of worm-like micelles includes three stages: nucleation, cluster fusion and micelle fusion.And the vesicle formation has five stages: nucleation, cluster fusion, micelle fusion, disc-shaped micelles and disc-shaped micelle coiling. Compared with NaSal, 2SHNC presents stronger ability to promote micelle fusion, which can be confirmed by two facts: the first is that the work-like micelle could be obtained at lower 2SHNC concentration;the second is that the 2SHNC could promote to form more complex micelle of vesicle. Furthermore, the work-like micelle promoted by the 2SHNC exhibits stronger tensile strength tested by non-axial stretching, meaning that the 2SHNC could induce to form longer worm-like micelle and possesses better viscoelastic.