噻吩类阳离子表面活性剂的制备及其表面活性研究

Preparation of Thiophene Cationic Surfactant and Its Surface Activity

本文制备了一系列噻吩阳离子表面活性剂,代号NAT-n,n为烷基侧链中的亚甲基数目,n=8,10,12,14,16。采用Wilhelmy铂金板法测定了该类表面活性剂的表面张力。实验发现,该噻吩类阳离子表面活性剂的浓度为48μmol·L^-1时,其水溶液的表面张力低至23.45 mN·m^-1。与常见的阳离子季铵盐表面活性剂相比,该噻吩类阳离子表面活性剂具有更好的降低水表面张力的能力及更高的表面活性。分子中烷基链的长度影响该类表面活性剂分子在气水界面的最大吸附和分子之间界面排列的紧密程度,随着烷基链增长,该类噻吩阳离子表面活性剂最大吸附量增加,分子所占据的表面积降低,在气水界面排列得更加紧密,从而使其水溶液的表面张力降低,临界胶束浓度也随之降低。

Cationic surfactants with thiophene are prepared with the code name of NAT-n(n=8,10,12,14,16)in this study.The surface tension of the surfactants is determined by Wilhelmy platinum plate method.It is found that the surface tension of its aqueous solution is as low as 23.45 mN·m^-1 at a concentration of 48μmol·L^-1.It suggests that the thiophene cationic surfactants prepared have better performance in water surface tension lowering and higher surface activity than conventional cationic quaternary ammonium surfactants.The length of alkyl chain is found to be influential on its water surface adsorption and interface closeness.With the prolonged alkyl chain,its maximum adsorption on water surface has increased and the surface occupation area has decreased,leading to closer molecular arrangement,lower surface tension and lesser critical micelle concentration values.