Free Energy of Scission for Sodium Laureth-1-Sulfate Wormlike Micelles.
Free Energy of Scission for Sodium Laureth-1-Sulfate Wormlike Micelles.
复制标题
月桂醇聚醚-1-硫酸钠蠕虫状胶束的断裂自由能。
作者：
K. Vogtt;Hanqiu Jiang;G. Beaucage;M. Weaver
蠕虫状胶束 (WLM) 是纳米级自组装成分，由于其粘弹性，从洗发水到压裂液等许多产品中都出现了这种成分。它们的流变行为很大程度上取决于胶束的轮廓长度以及胶束随之而来的重叠和缠结倾向。微米量级的大轮廓长度一方面是蠕虫状胶束的断裂焓与另一方面熵因素（例如分散的混合熵、水分子和反离子的有序性以及分支点的流动性）之间微妙平衡的结果。使用小角中子散射在不同温度下测定了由 1-月桂醇聚醚-1-硫酸钠组装而成的蠕虫状胶束的结构和轮廓长度。结果允许计算熵和熵以及分裂自由能，并用于严格评估从平均场理论确定胶束分裂能的常用方法。在比较分支和非分支 WLM 时，观察到有趣的行为，这可能反映了断链的机制差异。
Wormlike micelles (WLMs) are nanoscale, self-assembled components of many products from shampoos to fracking fluids due to their viscoelasticity. Their rheological behavior is largely governed by the contour length of the micelles and the concomitant propensity of the micelles to overlap and entangle. The large contour lengths, on the order of micrometers, is the result of a delicate balance between the scission enthalpy of the wormlike micelles on the one hand and entropic factors such as the mixing entropy of dispersion, the ordering of water molecules and counterions, and the mobility of branch points on the other hand. The structure and contour length of wormlike micelles assembled from sodium laureth-1-sulfate was determined at various temperatures using small-angle neutron scattering. The results allow the calculation of the enthalpy and entropy as well as the free energy of scission and are employed to critically evaluate the common methods to determine micellar scission energy from mean-field theory. Interesting behavior is observed when comparing branched and unbranched WLMs that may reflect on mechanistic differences in chain scission.