Single chain elasticity and thermoelasticity of polyethylene

TL;DR

This study uses Monte Carlo simulations to analyze the elasticity of polyethylene chains, confirming the wormlike chain model's applicability up to 65% extension and exploring solvent effects on elasticity.

Contribution

It demonstrates the temperature-dependent persistence length in the wormlike chain model and highlights its limitations beyond 65% extension for polyethylene.

Findings

Wormlike chain model fits elasticity data up to 65% extension

Persistence length varies with temperature

Solvent effects influence elasticity and energy contributions

Abstract

Single-chain elasticity of polyethylene at $\theta$ point up to 90% of stretching with respect to its contour length is computed by Monte-Carlo simulation of an atomistic model in continuous space. The elasticity law together with the free-energy and the internal energy variations with stretching are found to be very well represented by the wormlike chain model up to 65% of the chain elongation, provided the persistence length is treated as a temperature dependent parameter. Beyond this value of elongation simple ideal chain models are not able to describe the Monte Carlo data in a thermodynamic consistent way. This study reinforces the use of the wormlike chain model to interpret experimental data on the elasticity of synthetic polymers in the finite extensibility regime, provided the chain is not yet in its fully stretched regime. Specific solvent effects on the elasticity law and the partition between energetic and entropic contributions to single chain elasticity are investigated.