The coil-globule transition of polymers of long rigid monomers connected by flexible spacers

TL;DR

This paper models a polymer with long rigid segments and flexible spacers, revealing a strongly first-order coil-globule transition with a crystalline globule and swollen coil, using a cell theory approach.

Contribution

It introduces a simple model for polymers with rigid segments and flexible spacers, analyzing the coil-globule transition with a novel cell theory method.

Findings

Transition is strongly first order

Globule is crystalline in nature

Cell theory effectively calculates globule free energy

Abstract

A simple model of a polymer with long rigid segments which interact via excluded volume repulsions and short ranged attractions is proposed. The coil-globule transition of this model polymer is strongly first order, the globule is crystalline and the coil which coexists with the globule is swollen. A virial expansion truncated at low order is shown to provide a very poor approximation to the free energy and so a cell theory is used to calculate the free energy of the globule.