Centro de Investigação em Química, Department of Chemistry and Biochemistry, Faculty of Sciences, University of Porto, Rua do Campo Alegre, No 687, P-4169-007 Porto, Portugal.
Colloids Surf B Biointerfaces. 2011 Aug 1;86(1):65-70. doi: 10.1016/j.colsurfb.2011.03.017. Epub 2011 Mar 23.
Amino acid-derived surfactants have increasingly become a viable biofriendly alternative to petrochemically based amphiphiles as speciality surfactants. Herein, the Krafft temperatures and critical micelle concentrations (cmc) of three series of novel amino acid-derived surfactants have been determined by differential scanning microcalorimetry and surface tension measurements, respectively. The compounds comprise cationic molecules based on serine and tyrosine headgroups and anionic ones based on 4-hydroxyproline headgroups, with varying chain lengths. A linear dependence of the logarithm of cmc on chain length is found for all series, and in comparison to conventional ionic surfactants of equal chain length, the new amphiphiles present lower cmc and lower surface tension at the cmc. These observations highlight their enhanced interfacial performance. For the 18-carbon serine-derived surfactant the effects of counterion change and of the presence of a cis-double bond in the alkyl chain have also been investigated. The overall results are discussed in terms of headgroup and alkyl chain effects on micellization, in the light of available data for conventional surfactants and other types of amino acid-based amphiphiles reported in the literature.
氨基酸衍生表面活性剂作为特种表面活性剂，越来越成为一种可行的、对石油化工基两亲物有吸引力的生物友好替代品。在此，通过差示扫描微量热法和表面张力测量分别确定了三系列新型氨基酸衍生表面活性剂的克拉夫特点温度和临界胶束浓度（cmc）。这些化合物包含基于丝氨酸和酪氨酸头基的阳离子分子和基于 4-羟脯氨酸头基的阴离子分子，其链长不同。所有系列均发现 cmc 的对数值与链长呈线性关系，与具有相同链长的常规离子表面活性剂相比，新的两亲物具有更低的 cmc 和更低的 cmc 表面张力。这些观察结果突出了它们增强的界面性能。对于 18 碳丝氨酸衍生表面活性剂，还研究了反离子变化和烷基链中顺式双键存在的影响。根据现有常规表面活性剂和文献中报道的其他类型氨基酸基两亲物的数据，从头基和烷基链对胶束化的影响方面讨论了整体结果。
