Tanahashi Kotaro, Koga Tsuyoshi
Department of Polymer Chemistry, Kyoto University, Kyoto 615-8510, Japan.
Gels. 2021 Aug 29;7(3):129. doi: 10.3390/gels7030129.
Slide-ring (SR) gels, a new type of gels that have cross-links moving along the chains, are known to have unique mechanical characteristics. In the case of biaxial deformations, it has been experimentally shown that the stress-strain (S-S) relationships of SR gels can be well described by the neo-Hookean (NH) model. This behavior is quite different from that of conventional chemical gels, where the S-S curves deviate from the NH model. To understand the molecular mechanism of such peculiar elastic properties of SR gels, we studied the effects of movable cross-links by using molecular simulations and theoretical analysis. We calculate the S-S relationships in biaxial deformation for two types of models: slip model, where the cross-links can slide along chains representing SR gels, and non-slip model, which corresponds to conventional chemical gels. In the theoretical analysis, we calculate the S-S relationships by using the models with the Gaussian and the Langevin chains to investigate the nonlinear stretching effect of the chain in the slip and non-slip models. As a result, we found that the peculiar elastic behaviors of SR gels in biaxial deformations are well explained by the effect of movable cross-links suppressing the nonlinear stretching of the chain.
滑动环（SR）凝胶是一种新型凝胶，其交联点可沿链移动，已知具有独特的力学特性。在双轴变形的情况下，实验表明SR凝胶的应力-应变（S-S）关系可以用新胡克（NH）模型很好地描述。这种行为与传统化学凝胶有很大不同，传统化学凝胶的S-S曲线偏离NH模型。为了理解SR凝胶这种特殊弹性特性的分子机制，我们通过分子模拟和理论分析研究了可移动交联点的影响。我们计算了两种模型在双轴变形中的S-S关系：滑动模型，其中交联点可沿代表SR凝胶的链滑动；非滑动模型，它对应于传统化学凝胶。在理论分析中，我们使用高斯链和朗之万链模型计算S-S关系，以研究滑动和非滑动模型中链的非线性拉伸效应。结果发现，SR凝胶在双轴变形中的特殊弹性行为可以通过可移动交联点抑制链的非线性拉伸效应得到很好的解释。
