Persistence length and plateau modulus of semiflexible entangled polymers in primitive chain network simulations

TL;DR

This study extends a primitive chain network model to include bending rigidity, revealing that the plateau modulus of semiflexible polymers increases with persistence length, aligning with experimental observations.

Contribution

The paper introduces a modified PCN model incorporating bending rigidity at the entanglement scale, providing new insights into the G_0-L_p relationship.

Findings

G_0 scales as L_p^(2/3)

Simulation results agree with experimental data

Entanglement length remains fixed across rigidity variations

Abstract

The relationship between the plateau modulus (G_0) and the persistence length (L_p) of entangled semiflexible polymers is still uncertain. Some previous theoretical models have predicted that G_0 decreases with increasing L_p, while experiments indicated the opposite. In this study, we extend the primitive chain network (PCN) model to incorporate bending rigidity at the scale of the entanglement length, consistently with the coarse graining of the model. Simulations investigate the effects of rigidity (and of molecular weight) on chain conformation and relaxation modulus. Our results reveal a relationship described as G_0~L_p^(2/3), indicating that G_0 increases with increasing L_p, consistently with experiments. It should be considered, however, that implicit in our simulations is the condition that the entanglement length is kept fixed with changing L_p.