CNR-ISC, Uos Sapienza, Piazzale A. Moro, 2, 00185, Roma, Italy.
Dipartimento di Scienze di Base e Applicate per l'Ingegneria, Sapienza Università di Roma, via A. Scarpa, 14, 00161, Roma, Italy.
Sci Rep. 2018 Sep 26;8(1):14426. doi: 10.1038/s41598-018-32642-5.
Thermoresponsive microgels are polymeric colloidal networks that can change their size in response to a temperature variation. This peculiar feature is driven by the nature of the solvent-polymer interactions, which triggers the so-called volume phase transition from a swollen to a collapsed state above a characteristic temperature. Recently, an advanced modelling protocol to assemble realistic, disordered microgels has been shown to reproduce experimental swelling behavior and form factors. In the original framework, the solvent was taken into account in an implicit way, condensing solvent-polymer interactions in an effective attraction between monomers. To go one step further, in this work we perform simulations of realistic microgels in an explicit solvent. We identify a suitable model which fully captures the main features of the implicit model and further provides information on the solvent uptake by the interior of the microgel network and on its role in the collapse kinetics. These results pave the way for addressing problems where solvent effects are dominant, such as the case of microgels at liquid-liquid interfaces.
温敏性微凝胶是一种能够响应温度变化而改变其大小的聚合物胶体网络。这种特殊的特性是由溶剂-聚合物相互作用的性质驱动的，这种相互作用在高于特征温度时引发所谓的从溶胀到塌陷状态的体积相转变。最近，一种先进的建模协议被用来组装逼真的、无序的微凝胶，以再现实验中的溶胀行为和形态因子。在原始框架中，溶剂以隐含的方式被考虑，将溶剂-聚合物相互作用凝聚在单体之间的有效吸引力中。更进一步，在这项工作中，我们在显式溶剂中对真实的微凝胶进行了模拟。我们确定了一个合适的模型，该模型完全捕捉了隐含模型的主要特征，并进一步提供了关于溶剂在微凝胶网络内部的吸收以及其在塌陷动力学中的作用的信息。这些结果为解决溶剂效应占主导地位的问题铺平了道路，例如在液-液界面处的微凝胶的情况。
