水杨酸钠对DTAB/PAM复合体系自组装行为的影响

Effects of sodium salicylate on the self-assembly behavior of DTAB/PAM mixed system

通过粗粒度分子动力学模拟的方法研究了水杨酸钠(Na Sal)对聚丙烯酰胺(PAM)与表面活性剂十二烷基三甲基溴化铵(DTAB)复合体系自组装行为的影响。结果表明,随着添加的Na Sal浓度增大,DTAB/PAM聚集体经历了球形-棒状-球形的结构变化,且吸附到聚合物链上的DTAB分子数目先增大后减小。在DTAB/PAM聚集体中,聚合物PAM分子链位于DTAB胶束疏水内核与亲水层的交界处,有机盐Sal-插入到胶束内部。聚合物分子链的回转半径(Rg)随时间的变化以及聚集体中表面活性剂数目随时间的变化过程均可以分为3个阶段,且形成尺寸较大的DTAB/PAM聚集体需要更长的时间。

The effects of sodium salicylate（ Na Sal） on the self-assembly behavior of the mixed system of polyacrylamide（ PAM） and dodecyltrimethylammonium bromide（ DTAB） were studied by coarse-grained molecular dynamics simulation. The results indicate that,with the increase of Na Sal concentration,the aggregates of DTAB/PAM undergo a shape transition from sphere to rod then to sphere,and the number of DTAB molecules adsorbed onto HPAM chains first increases and then decreases. As for the DTAB/PAM aggregate,the PAM chain is located at the interface between the hydrophobic core and the hydrophilic layer of the DTAB micelle,and the Sal-ions are inserted into the interior of the micelle. The variations with time of the polymer chain＇s Rg and the number of surfactant molecules in the aggregate can be both divided into three stages. The formation of larger DTAB/PAM aggregates needs longer time.