Aqueous mixtures of di-n-decyldimethylammonium chloride/polyoxyethylene alkyl ether: Dramatic influence of tail/tail and head/head interactions on co-micellization and biocidal activity

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• 作者：Gaé ; tan Rauwel^a ; ^b ; Loï ; c Leclercq^b ; ^c ; Jacques Criquelion^a ; Jean-Marie Aubry^b ; ^c ; Vé ; ronique Nardello-Rataj^b ; ^c ; ^{veronique.rataj@univ-lille1.fr}
• 关键词：Di-n-alkyldimethylammonium chloride ; Polyoxyethylene alkyl ether ; Binary surfactant systems ; Mixed aggregates ; Biocidal activity ; Podand effect
• 刊名：Journal of Colloid and Interface Science
• 出版年：2012
• 期刊代码：125_00219797
• 类别：ch
• 出版时间：15 May, 2012
• 卷：374
• 期：1
• 页码：176-186
• 文件大小：1440 K

摘要

Mixed aggregate formation and synergistic interactions of binary surfactant mixtures of di-n-decyldimethylammonium chloride, [DiC₁₀][Cl], with polyoxyethylene alkyl ethers, C_iE_j (i = 10, 12, j = 4, 6, 8), have been investigated for various [DiC₁₀][Cl]/C_iE_j ratios. The critical aggregation concentration of the binary mixtures has been determined by tensiometry, and the aggregate characteristics (i.e., size and composition, free ammonium concentration) have been estimated using the pulsed field gradient NMR spectroscopy and a [DiC₁₀]-selective electrode. Diffusion coefficient measurements of micelles confirmed the synergistic interaction between the surfactants. It is thus shown that the formation of surface monolayers and mixed aggregates from [DiC₁₀][Cl]/C₁₀E_j mixtures is driven by both tail/tail and head/head interactions, whereas [DiC₁₀][Cl]/C₁₂E_j co-aggregation is mainly driven by tail/tail interactions. As a consequence, the co-aggregation phenomenon notably influences the biocidal activity of [DiC₁₀][Cl] on the Candida albicans fungi. In the presence of C₁₂E_j, the biocidal activity of the ammonium salt is inhibited due to the trapping of the cationic surfactants in the mixed aggregates, whereas in the presence of C₁₀E_j, the biocidal activity of the surfactant mixture is maintained. The mode of action is also confirmed by a faster increase in the zeta potential of a C. albicans suspension in the presence of [DiC₁₀][Cl]/C₁₀E₈ than in the presence of [DiC₁₀][Cl]/C₁₂E₈. Therefore, a judicious adjustment of the alkyl (i) and polyoxyethylene (j) chain lengths of C_iE_j avoids its antagonistic effect on the biocidal activity of [DiC₁₀][Cl].