Effects of Added Physical Cross-Linkers on Mechanical Properties of Polymer Networks

Abstract

The effects of added physical cross-linkers on the mechanical properties of polymer networks are studied by a computer simulation and a theoretical calculation. The physical cross-linkers are modeled with small attractive particles and are adsorbed on the networks. The particle adsorption on the networks serves as sacrificial bonds and enhances the mechanical strength and the extensibility of the networks. The subchains of the networks change the conformation from collapsed states to expanded states with increasing particle content. This conformational change leads the non-monotonic behavior of the mechanical properties of the networks. If the deformation rate is less than the inverse of the lifetime of the adsorption, the stress shows a relaxation with the conformational change of the subchains and the restructuring of inter-subchain physical bonds via particle adsorption. In contrast, if the deformation rate is fast, the networks are deformed before the structural change, and show higher mechanical strengths.