Laboratoire Charles Coulomb (L2C), Univ. Montpellier, CNRS, F-34095 Montpellier, France.
CNR-ISC Uos Sapienza, Piazzale A. Moro 2, IT-00185 Roma, Italy.
J Chem Phys. 2023 Feb 21;158(7):074905. doi: 10.1063/5.0134271.
The elasticity of disordered and polydisperse polymer networks is a fundamental problem of soft matter physics that is still open. Here, we self-assemble polymer networks via simulations of a mixture of bivalent and tri- or tetravalent patchy particles, which result in an exponential strand length distribution analogous to that of experimental randomly cross-linked systems. After assembly, the network connectivity and topology are frozen and the resulting system is characterized. We find that the fractal structure of the network depends on the number density at which the assembly has been carried out, but that systems with the same mean valence and same assembly density have the same structural properties. Moreover, we compute the long-time limit of the mean-squared displacement, also known as the (squared) localization length, of the cross-links and of the middle monomers of the strands, showing that the dynamics of long strands is well described by the tube model. Finally, we find a relation connecting these two localization lengths at high density and connect the cross-link localization length to the shear modulus of the system.
无序和多分散聚合物网络的弹性是软物质物理学中的一个基本问题，尚未得到解决。在这里，我们通过模拟二价和三价或四价斑片状粒子的混合物来自组装聚合物网络，这导致了类似于实验中随机交联系统的指数链长度分布。组装后，网络的连接性和拓扑结构被冻结，然后对所得系统进行表征。我们发现，网络的分形结构取决于组装的数密度，但具有相同平均价数和相同组装密度的系统具有相同的结构特性。此外，我们计算了交联和链中间单体的均方根位移（也称为（平方）定位长度）的长时间限制，表明长链的动力学很好地由管模型描述。最后，我们在高密度下找到了这两个定位长度之间的关系，并将交联的定位长度与系统的剪切模量联系起来。
