Time-resolved SANS for the determination of unimer exchange kinetics in block copolymer micelles
Time-resolved SANS for the determination of unimer exchange kinetics in block copolymer micelles
复制标题
时间分辨 SANS 用于测定嵌段共聚物胶束中的单聚体交换动力学
DOI：
10.1209/epl/i2001-00467-y
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发表时间：
2001
期刊：
影响因子：
1.8
通讯作者：
D. Richter
中科院分区：
文献类型：
--
作者：
L. Willner;A. Poppe;J. Allgaier;M. Monkenbusch;D. Richter
建立了一种时间分辨的SANS方法，用于测定平衡条件下聚合物胶束的unimer交换动力学。利用质子化和氘化物质在散射长度密度上的巨大差异，对PEP-PEO/DMF体系进行了测量。与理论预测相反，观察到的动力学由两个分离良好的过程组成。从温度相关的测量可以确定相应的活化能EA。基于Halperin和Alexander的标度预测的比较表明，快速过程可能与单一的unimer插入/排出机制有关。另一方面，这个缓慢的过程不能用现有的微观模型来解释。
A time-resolved SANS method was developed for the determination of unimer exchange kinetics of polymeric micelles under equilibrium conditions. Measurements were performed on the system PEP-PEO/DMF exploiting the large difference in scattering length density of protonated and deuterated species. In contrast to theoretical predictions the observed kinetics consists of two well-separated processes. From temperature-dependent measurements the corresponding activation energies EA could be determined. A comparison on the basis of a scaling prediction of Halperin and Alexander indicates that the fast process can be associated with a single unimer insertion/expulsion mechanism. The slow process, on the other hand, could not be explained on the basis of available microscopic models.