Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States.
ACS Macro Lett. 2021 May 18;10(5):531-537. doi: 10.1021/acsmacrolett.0c00909. Epub 2021 Apr 15.
The Flory-Rehner and Bray-Merrill swelling theories are venerable theories for calculating the swelling of polymer networks and are widely applied across polymer materials. Here, these theories are revised to include cyclic topological defects present in polymer networks by using a modified phantom network model. These closed-form equations assume defect contributions to the swelling elasticity to be linear and additive and allow different assumptions regarding prestrain of larger loops to be incorporated. To compare to the theories, swelling experiments are performed on end-linked poly(ethylene glycol) gels in which the topological defects (primary and secondary loops) have been previously measured. Gels with higher loop densities exhibit higher swelling ratios. An equation is derived to compare swelling models independent of knowledge of the Flory-Huggins χ parameter, showing that the revised swelling models for loop defects are more accurate than both the phantom network model that neglects loops and the Bray-Merrill equation.
弗洛里-雷纳和布雷-梅里尔溶胀理论是计算聚合物网络溶胀的经典理论，在聚合物材料中得到了广泛的应用。在这里，我们通过使用改进的幻影网络模型对这些理论进行了修订，以包括聚合物网络中存在的循环拓扑缺陷。这些封闭形式的方程假设缺陷对溶胀弹性的贡献是线性和可加的，并允许对更大环的预应变进行不同的假设。为了与理论进行比较，我们对端接聚（乙二醇）凝胶进行了溶胀实验，其中已经测量了拓扑缺陷（一级和二级环）。具有更高环密度的凝胶表现出更高的溶胀比。推导出一个方程来比较溶胀模型，而不依赖于弗洛里-哈金斯 χ 参数的知识，结果表明，考虑到环缺陷的修正溶胀模型比忽略环的幻影网络模型和布雷-梅里尔方程更准确。
