Abstract

The micellization of cetyltrimethylammonium bromide (CTAB) and bovine serum albumin (BSA) mixture has been studied conductometrically in aq. solutions of different diols (1,2-propanediol (1,2-PrD), 2,3-butanediol (2,3-BD), and 1,5-pentanediol (1,5-PD)) media over the temperature range from 298.15 K to 323.15 K to gain insight into the mode and degree of interaction amongst the investigated constituents. The critical micelle concentration (cmc) values of the CTAB + BSA mixtures were attained initially low but enhanced with the rise in temperature in all the media studied. The values of the CTAB + BSA mixtures in the different diols media followed the order: ${\mathit{cmc}}_{1,5-PD}>{\mathit{cmc}}_{1,2-\mathit{PrD}}>{\mathit{cmc}}_{2,3-BD}.$ The degree of micelle ionization (α) increased with increasing carbon chain length of diols and temperature. The Gibbs free energy (${\Delta G}_m^0$) values associated with the micellization of the CTAB + BSA mixture were negative and revealed a lowering of the spontaneity of micellization with increasing carbon chain length of the diols. The enthalpy (${\Delta H}_m^0$) and entropy (${\Delta S}_m^0$) changes of micellization revealed that the micellization was exothermic and mainly an enthalpy-controlled process in aq.1,2-PrD and 2,3-BD media while the process being endothermic, and entropy controlled in the 1,5-PD medium. The contribution of the solvent to the thermodynamic parameters was assessed from free energy of transfer (${\Delta G}_{m,t}^0$), enthalpy of transfer (${\Delta H}_{m,t}^0$), and entropy of transfer (${\Delta S}_{m,t}^0$) values. The enthalpy–entropy compensation parameters were also studied and discussed with proper reasoning.

摘要

十六烷基三甲基溴化铵 (CTAB) 和牛血清白蛋白 (BSA) 混合物的胶束化在水溶液中进行了电导研究。不同二醇（1,2-丙二醇 (1,2-PrD)、2,3-丁二醇 (2,3-BD) 和 1,5-戊二醇 (1,5-PD)）介质在温度范围内的溶液从 298.15 K 到 323.15 K，以深入了解所调查成分之间相互作用的模式和程度。CTAB + BSA 混合物的临界胶束浓度 ( cmc ) 值最初很低，但在所有研究的介质中随着温度的升高而提高。不同二醇介质中 CTAB + BSA 混合物的值遵循以下顺序：${\mathit{管理委员会}}_{\mathrm{1个},\mathrm{5个}-P丁}>{\mathit{管理委员会}}_{\mathrm{1个},\mathrm{2个}-\mathit{博士}}>{\mathit{管理委员会}}_{\mathrm{2个},\mathrm{3个}-乙丁}.$胶束电离度 ( α ) 随着二醇碳链长度和温度的增加而增加。吉布斯自由能 (${△G}_{米}^0$) 与 CTAB + BSA 混合物的胶束化相关的值是负的，并表明随着二醇碳链长度的增加，胶束化的自发性降低。焓 (${△H}_{米}^0$) 和熵 (${△\mathrm{小号}}_{米}^0$) 胶束化的变化表明胶束化是放热的，在 aq.1,2-PrD 和 2,3-BD 介质中主要是一个焓控过程，而在 1,5-PD 介质中是吸热过程和熵控制。溶剂对热力学参数的贡献是从转移自由能评估的（${△G}_{米,吨}^0$), 传递焓 (${△H}_{米,吨}^0$), 和传递熵 (${△\mathrm{小号}}_{米,吨}^0$) 值。还通过适当的推理研究和讨论了焓-熵补偿参数。