Aggregation Behavior of Imidazolium‐Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions
Aggregation Behavior of Imidazolium‐Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions
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DOI：
10.1002/jsde.12270
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发表时间：
2019-05
影响因子：
1.6
通讯作者：
Xiujie Yang;Peng Zhang;Wen-jiao Lv;Ting Zhou;Li-Rong Peng;Mingwei Zhao
中科院分区：
文献类型：
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作者：
Xiujie Yang;Peng Zhang;Wen-jiao Lv;Ting Zhou;Li-Rong Peng;Mingwei Zhao
以天然氨基酸为抗衡离子，合成了3种咪唑类氨基酸离子液体表面活性剂：1-十四烷基-3-甲基咪唑L-氨基丙酸盐（[C14 mim][Ala]）、1-十四烷基-3-甲基咪唑L-2-吡咯烷羧酸盐（[C14 mim][Pro]）和1-十四烷基-3-甲基咪唑L-氨基氢化肉桂酸盐（[C14 mim][Phe]）.通过表面张力和电导率的测定，系统地研究了它们在水溶液中的吸附和自聚集行为。表面张力结果表明，反离子对AAILS的表面性质和胶束化行为有显著影响。[C14 mim][Pro]和[C14 mim][Phe]的胶束化在低温下是熵驱动的，但在高温下是焓驱动的，而[C14 mim][Ala]在整个温度范围内是焓驱动的，这是由于氨基酸抗衡离子的疏水性和大小的变化。[C14 mim][Phe]的表面活性上级优于具有相同烃链长度的常规咪唑盐基离子液体表面活性剂1-十四烷基-3-甲基咪唑溴盐（C14 mimBr），表明芳香族配体可以促进胶束形成过程。
Three kinds of imidazolium‐based amino acid ionic liquid surfactants (AAILS),1‐tetradecyl‐3‐methylimidazoliumL‐aminopropionic acid salt ([C14mim][Ala]),1‐tetradecyl‐3‐methylimidazoliumL‐2‐pyrrolidinecarboxylic acid salt ([C14mim][Pro]), and1‐tetradecyl‐3‐methylimidazoliumL‐aminohydrocinnamic acid salt ([C14mim][Phe]), were synthesized by employing natural amino acids as counterions. Their adsorption and self‐aggregation behaviors in aqueous solution were investigated systematically by means of surface tension and electrical conductivity measurements. Surface tension results indicate that surface properties and micellization behavior of AAILS are significantly affected by counterions. The micellization of [C14mim][Pro] and [C14mim][Phe] is entropy‐driven at low temperatures but enthalpy‐driven at high temperatures, whereas [C14mim][Ala] is enthalpy‐driven throughout the whole temperature range, owing to the variation in hydrophobicity and size of amino acid counterions. The surface activity of [C14mim][Phe] is superior to that of conventional imidazolium‐based ionic liquid surfactants with the same hydrocarbon chain length,1‐tetradecyl‐3‐methylimidazolium bromide (C14mimBr), indicating that the aromatic counterion can promote the micellar formation process.