Marginally compact phase and ordered ground states in a model polymer with side spheres

TL;DR

This study investigates how adding side spheres to a polymer model induces a new marginally compact phase with ordered, lower-dimensional structures like sheets and helices, revealing insights into polymer and biomolecular phase behavior.

Contribution

It introduces a novel polymer model with side spheres that exhibits a unique marginally compact phase and ordered structures, bridging conventional polymer and biomolecular phases.

Findings

Addition of side spheres modifies standard polymer behavior.

Discovery of a marginally compact phase with ordered structures.

Identification of a first-order transition to ordered states.

Abstract

We present the results of a quantitative study of the phase behavior of a model polymer chain with side spheres using two independent computer simulation techniques. We find that the mere addition of side spheres results in key modifications of standard polymer behavior. One obtains a novel marginally compact phase at low temperatures, the structures in this phase are reduced in dimensionality and are ordered, they include strands assembled into sheets and a variety of helices, and at least one of the transitions on lowering the temperature to access these ordered states is found to be first order. Our model serves to partially bridge conventional polymer phases with biomolecular phases.