State Key Laboratory of Polymer Materials Engineering, Polymer Research Institute, Sichuan University, Chengdu 610065, P. R. China.
Soft Matter. 2015 Jun 21;11(23):4614-20. doi: 10.1039/c5sm00677e.
Smart surfactant wormlike micelles (SWLMs), responsive to external stimuli, are a particularly recent area of development, yet highly promising, given the versatility of the materials but simplicity of the design. Here, we developed a pH-switchable wormlike micellar system based on a "pseudo" gemini surfactant (named as EAMA) formed by a mixture of N-erucamido-N,N-dimethylamine (UC22AMPM) and maleic acid with a molar ratio of 2 : 1, and compared the "pseudo" gemini worm system with UC22AMPM in the presence of hydrochloric acid (EAHCl). It was found that both maleic acid and hydrochloric acid can protonate the ultra-long-chain tertiary amine into a quaternary ammonium surfactant, thereby forming wormlike micelles; however, much stronger viscoelastic behavior was evidenced in the maleic acid system because one protonated maleic acid molecule can "bridge" two quaternized UC22AMPM molecules via electrostatic attraction. In contrast, the EAHCl system just shows a "mono" quaternary ammonium feature with a weak viscosity buildup. In addition, the maleic acid-based worm system was found to be more thermo-sensitive than conventional wormlike micelles, which also originates due to its "pseudo" gemini architecture.
智能表面活性剂蠕虫状胶束（SWLMs）对外界刺激响应，是一个特别新的发展领域，极具发展前景，因为材料的多功能性和设计的简单性。在这里，我们开发了一种基于“假”双子表面活性剂（命名为 EAMA）的 pH 可切换蠕虫状胶束体系，该表面活性剂由 N-硬脂酰胺-N,N-二甲基胺（UC22AMPM）和马来酸以摩尔比 2：1 混合而成，并在盐酸（EAHCl）存在的情况下将“假”双子蠕虫体系与 UC22AMPM 进行了比较。结果发现，马来酸和盐酸都可以将超长链叔胺质子化为季铵表面活性剂，从而形成蠕虫状胶束；然而，在马来酸体系中表现出更强的粘弹性行为，因为一个质子化的马来酸分子可以通过静电吸引“桥接”两个季化的 UC22AMPM 分子。相比之下，EAHCl 体系仅表现出“单”季铵特征，且粘度增加较弱。此外，发现基于马来酸的蠕虫体系比常规蠕虫状胶束更热敏，这也归因于其“假”双子结构。
