Moitzi Christian, Freiberger Norbert, Glatter Otto
Institut für Chemie, Universität Graz, Heinrichstrasse 28, A-8010 Graz, Austria.
J Phys Chem B. 2005 Aug 25;109(33):16161-8. doi: 10.1021/jp0441691.
A highly viscoelastic micellar solution of nonionic surfactants in a dilute region was recently reported. A transient network of wormlike micelles formed with the addition of short-EO-chain poly(oxyethylene) dodecyl ether surfactants (C12EO(j), j = 1-4) to poly(oxyethylene) cholesteryl ethers (ChEO(m), m = 10 and 15). A gradual increase in micellar length with an increasing C12EO(j) concentration was assumed from the results of model calculations and rheological measurements. We report in this study the results of structural investigations with small-angle neutron scattering (SANS) to confirm this assumption. Tuning from spherical to wormlike and to locally flat structures can be achieved by way of three methods. One can either increase the C12EO(j) concentration or decrease j (smaller headgroup size) at a fixed concentration of C12EO(j). The third possibility is to increase the temperature at a fixed composition. All three methods result in the same structural transition. The formation of a transient network of wormlike micelles analogous to polymer solutions can be observed with dynamic light scattering (DLS). A stretched exponential approach was applied to fit the correlation functions.
最近报道了一种在稀溶液区域中由非离子表面活性剂形成的高粘弹性胶束溶液。向聚氧乙烯胆固醇醚（ChEO(m)，m = 10 和 15）中添加短 EO 链聚氧乙烯十二烷基醚表面活性剂（C12EO(j)，j = 1 - 4）时，会形成蠕虫状胶束的瞬态网络。根据模型计算和流变学测量结果推测，随着 C12EO(j) 浓度增加，胶束长度会逐渐增加。在本研究中，我们报告了用小角中子散射（SANS）进行结构研究的结果，以证实这一推测。通过三种方法可以实现从球形结构到蠕虫状结构再到局部扁平结构的转变。可以在固定的 C12EO(j) 浓度下增加 C12EO(j) 的浓度，或者减小 j（较小的头基尺寸）。第三种可能性是在固定组成下升高温度。所有这三种方法都会导致相同的结构转变。用动态光散射（DLS）可以观察到类似于聚合物溶液的蠕虫状胶束瞬态网络的形成。应用拉伸指数方法来拟合相关函数。
