Singh SK, Nilsson S
Department of Pharmaceutics, Pharmacia & Upjohn AB, S-751 82 Uppsala, Sweden
J Colloid Interface Sci. 1999 May 1;213(1):152-159. doi: 10.1006/jcis.1999.6121.
A titration calorimetric study of the interaction between nonionic cellulose ethers and ionic surfactant (SDS) has been extended to a larger number of polymers to explore the effect of variation of polymer hydrophobicity on the energetics of the process. "Hydrophobicity" as used here is an overall effect of the nature, degree, and number of substituents and is characterized by the cloud point and (aqueous) surface tension lowering abilities of the polymer. A direct correlation is found between the extent of "hydrophobicity" and the endo-enthalpic peak in the initial SDS concentration region of interaction. However, the overall mechanism of interaction is similar for all the polymers, being dominated by polymer-surfactant interactions initially and converting into a surfactant-surfactant interaction process at higher SDS concentrations. The importance of polymer characteristics thus becomes weaker at the later stages of the process. Differences between the polymers is also reduced by an increase of temperature, leading to a near overlap of observed enthalpy curves at 40 degrees C. The energetics of interaction are also mirrored by the isothermal surfactant binding curves and the changes in macroscopic and microviscosity of the system. Copyright 1999 Academic Press.
一项关于非离子型纤维素醚与离子型表面活性剂（SDS）相互作用的滴定量热研究已扩展到更多聚合物，以探讨聚合物疏水性变化对该过程能量学的影响。此处所用的“疏水性”是取代基的性质、程度和数量的综合效应，其特征在于聚合物的浊点和（水溶液）降低表面张力的能力。在相互作用的初始SDS浓度区域，发现“疏水性”程度与吸热峰之间存在直接相关性。然而，所有聚合物的总体相互作用机制相似，最初以聚合物 - 表面活性剂相互作用为主，在较高SDS浓度下转变为表面活性剂 - 表面活性剂相互作用过程。因此，在该过程的后期，聚合物特性的重要性变得较弱。温度升高也会减少聚合物之间的差异，导致在40℃时观察到的焓曲线几乎重叠。相互作用的能量学也反映在等温表面活性剂结合曲线以及系统宏观和微观粘度的变化上。版权所有1999年学术出版社。
