Bai Guangyue, Nichifor Marieta, Lopes António, Bastos Margarida
CIQ (UP), Department of Chemistry, Faculty of Sciences, University of Porto, R. Campo Alegre, 687, P-4169-007 Porto, Portugal.
J Phys Chem B. 2005 Nov 24;109(46):21681-9. doi: 10.1021/jp054154i.
Microcalorimetric techniques, combined with turbidity measurements, were used to study the thermodynamics of self-assembling of hydrophobically modified cationic polysaccharides and their mixtures with oppositely charged surfactants in aqueous solution. The studied polyelectrolytes were a series of polymers based on dextran having pendant N-(2-hydroxypropyl)-N,N-dimethyl-N-alkylammonium chloride groups randomly distributed along the polymer backbone. The parameters for their micellization process are evaluated from the results of the observed dilution enthalpy curves and compared with those of the related cationic surfactants (DTAC and CTAC). The microcalorimetric results for the mixed systems (polyelectrolytes with oppositely charged surfactants) are used along with turbidity measurements to characterize systematically the thermodynamics of their interaction. The phase behavior is described and the interaction enthalpies are derived from the differences between the observed enthalpy curves with and without polyelectrolyte. Therefore, we discuss in detail the effect of changing the alkyl chain length of polyelectrolyte pendant groups, the molecular weight of the dextran backbone, and the temperature of the measurements on the interactions between polyelectrolyte and surfactant.
微量量热技术与浊度测量相结合，用于研究疏水改性阳离子多糖及其与带相反电荷表面活性剂在水溶液中的混合物的自组装热力学。所研究的聚电解质是一系列基于葡聚糖的聚合物，其侧链N-(2-羟丙基)-N,N-二甲基-N-烷基氯化铵基团沿聚合物主链随机分布。根据观察到的稀释焓曲线结果评估其胶束化过程的参数，并与相关阳离子表面活性剂（十二烷基三甲基氯化铵和十六烷基三甲基氯化铵）的参数进行比较。混合体系（聚电解质与带相反电荷表面活性剂）的微量量热结果与浊度测量一起用于系统地表征其相互作用的热力学。描述了相行为，并从有无聚电解质时观察到的焓曲线差异中得出相互作用焓。因此，我们详细讨论了改变聚电解质侧链烷基链长度、葡聚糖主链分子量以及测量温度对聚电解质与表面活性剂之间相互作用的影响。
