CO2-Switchable Viscoelastic Fluids Based on a Pseudogemini Surfactant

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• 作者：Yongmin Zhang ; Yujun Feng ; Yuejiao Wang ; Xiangliang Li
• 刊名：Langmuir
• 出版年：2013
• 出版时间：April 2, 2013
• 年：2013
• 卷：29
• 期：13
• 页码：4187-4192
• 全文大小：331K
• 年卷期：v.29,no.13(April 2, 2013)
• ISSN：1520-5827

文摘

Recent research has highlighted a growing focus on stimuli-responsive surfactant wormlike micelles (WLMs), particularly those with switchability. Here we report CO₂-switchable WLMs based on the commercial anionic surfactant sodium dodecyl sulfate (SDS) and N,N,N鈥?N鈥?tetramethyl-1,3-propanediamine (TMPDA) mixed in a mole ratio of 2:1. When CO₂ is bubbled into an aqueous mixture of these reactants, the TMPDA molecules are protonated to form quaternary ammonium species, two of which in the same protonated TMPDA molecule 鈥渂ridge鈥?two SDS molecules by noncovalent electrostatic attraction, behaving like a pseudogemini surfactant and forming viscoelastic WLMs as verified by cryo-TEM. Upon removal of CO₂, the quaternized spacers are deprotonated back to tertiary amines, dissociating the pseudogeminis back to conventional SDS molecules that form low-viscosity spherical micelles. Such a reversible sphere-to-worm transition could be repeated several cycles without a loss of response to CO₂.