Interplay between Hydrogen Bond Network and Entangled Network in Polymers During Stretching Based on Molecular Simulations

Abstract

Mechanical properties of polymers can be regulated by changing the numbers of hydrogen bonds and entanglement points. However, the interplay between hydrogen bond network and entangled network during stretching has not been fully studied. We performed molecular dynamics simulations to investigate the changes of hydrogen bonds and entanglements during stretching. The stretching causes the orientation of local segments, leading to the entanglement sliding and disentanglements at different strain regions. Then, the number of entanglement points keeps constant at first and then decreases with increasing strain. Differently, the orientation of local segments can cause the change of chain conformation, which leads to the breakage of hydrogen bonds. Thus, the number of hydrogen bonds decreases with the increase of strain. Simulation results also demonstrated that the number of hydrogen bonds decreases faster during stretching in systems containing more entanglements. In systems with different hydrogen bond site contents, the initial number of entanglement nodes and its decline range during stretching increase firstly and then decrease with the increase of hydrogen bond site content.