Synthesis of two biofriendly anionic surfactants (N-n-decanoyl-l-valine and N-n-decanoyl-l-leucine) and their mixed micellization with nonionic surfactant Mega-10 in Tris-buffer medium at pH 9
作者:Sibani Das、Susmita Maiti、Soumen Ghosh
DOI:10.1039/c3ra44677h
日期:——
Two biofriendly anionic amino acid surfactants (AAS), N-n-decanoyl-L-valine (C10-val) and N-n-decanoyl-L-leucine (C10-leu) were synthesized and mixed micellization of them with nonionic surfactant N-decanoyl-N-methyl-glucamine (Mega-10) was investigated by tensiometry and fluorimetry in 50 mM Tris-buffer (pH = 9) medium at 298 K. The critical micelle concentration (cmc), surface properties, e.g., Gibbs surface excess (Γmax), area of exclusion per surfactant monomer (Amin) and surface pressure at cmc (Πcmc) were determined. Gibbs free energy of micellization (ΔG0m) and Gibbs free energy of adsorption (ΔG0ads) were also determined. Both the free energy values are negative indicating the spontaneity and stability of the mixed micelles. The size of the micelles was determined by dynamic light scattering (DLS) measurements. The deviation of mixed micelles from the ideal behavior was discussed on the basis of Clint, Motomura, Rubingh (regular solution theory), Rosen and Maeda's theory. Rubingh–Holland theory was applied on the ternary systems made by these three surfactants. The compositions of mixed micelle, the activity coefficients and the corresponding interaction parameters were evaluated from these theories. The interaction parameters (β) are negative, indicating attractive interaction between the ionic and nonionic surfactants. The micellar aggregation number (Nagg) and micropolarity were evaluated using steady state fluorescence measurements and the packing parameter (P) was determined on the basis of Israelachvili's theory. The standard free energy changes associated with the transfer of surfactant tail due to micellization of pure, binary and ternary combinations of surfactants were determined from Nagarajan's model. We report for the first time in detail the binary and ternary combinations using amino acid based surfactants.
研究人员合成了两种生物友好型阴离子氨基酸表面活性剂(AAS):N-正-癸酰基-L-缬氨酸(C10-val)和 N-正-癸酰基-L-亮氨酸(C10-leu),并在 50 mM Tris 缓冲溶液(pH = 9)介质(298 K)中通过张力测定法和荧光测定法研究了它们与非离子表面活性剂 N-癸酰基-N-甲基葡萄糖胺(Mega-10)的混合胶束化。临界胶束浓度(cmc)、表面特性,如测定了临界胶束浓度(cmc)、表面特性,如吉布斯表面过量(Γmax)、每个表面活性剂单体的排斥面积(Amin)和 cmc 时的表面压力(Πcmc)。还测定了胶束化吉布斯自由能(ΔG0m)和吸附吉布斯自由能(ΔG0ads)。这两个自由能值均为负值,表明混合胶束具有自发性和稳定性。胶束的大小是通过动态光散射(DLS)测量确定的。根据 Clint、Motomura、Rubingh(常规溶液理论)、Rosen 和 Maeda 的理论,讨论了混合胶束偏离理想行为的问题。Rubingh-Holland 理论适用于这三种表面活性剂组成的三元体系。根据这些理论评估了混合胶束的组成、活性系数和相应的相互作用参数。相互作用参数(β)为负值,表明离子型表面活性剂和非离子型表面活性剂之间存在吸引作用。胶束聚集数(Nagg)和微泼度是通过稳态荧光测量进行评估的,而堆积参数(P)则是根据 Israelachvili 理论确定的。根据 Nagarajan 模型确定了纯表面活性剂、二元表面活性剂和三元表面活性剂组合胶束化引起的表面活性剂尾部转移相关的标准自由能变化。我们首次详细报告了使用氨基酸基表面活性剂的二元和三元组合。