Hiroi Takashi, Shibayama Mitsuhiro
Department of Chemistry, School of Science, University of Tokyo;
Institute for Solid State Physics, University of Tokyo;
J Vis Exp. 2017 Jan 9(119):54885. doi: 10.3791/54885.
A protocol for measuring polydispersity of concentrated polymer solutions using dynamic light scattering is described. Dynamic light scattering is a technique used to measure the size distribution of polymer solutions or colloidal particles. Although this technique is widely used for the assessment of polymer solutions, it is difficult to measure the particle size in concentrated solutions due to the multiple scattering effect or strong light absorption. Therefore, the concentrated solutions should be diluted before measurement. Implementation of the confocal optical component in a dynamic light scattering microscope helps to overcome this barrier. Using such a microscopic system, both transparent and turbid systems can be analyzed under the same experimental setup without a dilution. As a representative example, a size distribution measurement of a temperature-responsive polymer solution was performed. The sizes of the polymer chains in an aqueous solution were several tens of nanometers at a temperature below the lower critical solution temperature (LCST). In contrast, the sizes increased to more than 1.0 µm when above the LCST. This result is consistent with the observation that the solution turned turbid above the LCST.
本文描述了一种使用动态光散射测量浓聚合物溶液多分散性的方法。动态光散射是一种用于测量聚合物溶液或胶体颗粒尺寸分布的技术。尽管该技术广泛用于聚合物溶液的评估，但由于多重散射效应或强光吸收，在浓溶液中测量颗粒尺寸较为困难。因此，浓溶液在测量前应进行稀释。在动态光散射显微镜中使用共焦光学组件有助于克服这一障碍。使用这样的微观系统，透明和浑浊系统都可以在相同的实验装置下进行分析，而无需稀释。作为一个代表性的例子，对温度响应性聚合物溶液进行了尺寸分布测量。在低于下临界溶液温度（LCST）的温度下，水溶液中聚合物链的尺寸为几十纳米。相比之下，当高于LCST时，尺寸增加到超过1.0 µm。这一结果与在LCST以上溶液变浑浊的观察结果一致。
