Aggregation Behavior of Imidazolium‐Based Amino Acid Ionic Liquid Surfactants in Aqueous Solution: The Effect of Amino Acid Counterions

Abstract

Three kinds of imidazolium‐based amino acid ionic liquid surfactants (AAILS), 1‐tetradecyl‐3‐methylimidazolium L‐aminopropionic acid salt ([C14mim][Ala]), 1‐tetradecyl‐3‐methylimidazolium L‐2‐pyrrolidinecarboxylic acid salt ([C14mim][Pro]), and 1‐tetradecyl‐3‐methylimidazolium L‐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.

Does thermotropic liquid crystalline self-assembly control biological activity in amphiphilic amino acids? – tyrosine ILCs as a case study

“…It is therefore important to further investigate and understand the potential of ILCs as antimicrobial agents. Several groups worldwide have investigated amino acid ILCs (and ILs) and the major focus was put on their thermotropic 25,[32][33][34][35][36][37] and lyotropic phase behaviour 34,[38][39][40][41][42][43][44][45][46] as well as solvation properties. 37,[47][48][49][50][51] Biological properties of amino acid ILCs, on the other hand, remain almost unexplored.…”

Role of isomers and steric hindrance in the micellization of carboxylated carbosilane surfactants

“…CMC values for each investigated carboxylated carbosilane surfactants increase regularly with temperature increase mainly resulting from (1) disruption of the ordered water structure surrounding the hydrophobic carbosilane parts is unfavorable to aggregate formation, (2) decreasing the hydration of the hydrophilic group which facilitates micellization. Obviously, the second factor is predominant in micellization process for Me‐Si 2 C‐COONa, Et‐Si 2 C‐COONa, Si 2 C‐La‐COONa, Ph‐Si 2 C‐COONa, and Cy‐Si 2 C‐COONa in the studied temperature range (De et al, 2010; Frizzo et al, 2015; Mata et al, 2005; Mosquera et al, 1998; Yang et al, 2019). In addition, the CMC values of Me‐Si 2 C‐COONa, Et‐Si 2 C‐COONa, Si 2 C‐La‐COONa, Ph‐Si 2 C‐COONa, and Cy‐Si 2 C‐COONa at 25°C are good in agreement with that obtained by surface tension measurements.…”

Aggregation and Adsorption Behavior of Cationic Surfactants (Cetyltrimethylammonium Bromide and Dodecyltrimethylammonium Bromide) in Aqueous Solutions of Antibiotic Drug (Amikacin Sulphate) at Different Temperatures

“…In addition to CMC and X CMC values, the standard thermodynamic parameters of micellization have been calculated at various temperatures to characterize complex aggregation behavior of CTAB and DTAB in aqueous solution of amikacin sulphate. The Van't Hoff relation has been used for computation of standard enthalpy of micelle formation () (Chauhan et al, 2018): where the slope ( d ln X CMC / dT ) has been calculated by fitting the ln X CMC isotherms to a second‐order polynomial and consequent temperature derivative as follows (Rahim et al, 2019; Yang et al, 2019): …”

“…where the slope (dlnX CMC /dT) has been calculated by fitting the lnX CMC isotherms to a second-order polynomial and consequent temperature derivative as follows (Rahim et al, 2019;Yang et al, 2019):…”