Self assembled linear polymeric chains with tuneable semiflexibility using isotropic interactions

TL;DR

This paper introduces a spherically symmetric potential that enables particles to self-assemble into tunable semiflexible polymer chains, allowing control over chain flexibility, branching, and phase behavior, with applications in modeling micellar systems and colloidal interactions.

Contribution

It demonstrates how isotropic potentials can produce effective directional interactions for self-assembling semiflexible polymers with controllable properties.

Findings

Particles form linear semiflexible chains with exponential length distribution.

At higher densities, chains organize into a line-hexagonal phase with a first-order transition.

Further density increase leads to a branched gel-like phase.

Abstract

We propose a two-body spherically symmetric (isotropic) potential such that particles interacting by the potential self assemble into linear semiflexible polymeric chains without branching. By suitable control of the potential parameters we can control the persistence length of the polymer, and can even introduce a controlled number of branches. Thus we show how to achieve effective directional interactions starting from spherically symmetric potentials. The self assembled polymers have a exponential distribution of chain lengths akin to what is observed for worm-like micellar systems. On increasing particle density the polymeric chains self-organize to an ordered line-hexagonal phase where every chain is surrounded by six parallel chains, the transition is first order. On further increase in monomer density, the order is destroyed and we get a branched gel like phase. This potential can be used to model semi-flexible equilibrium polymers with tunable semiflexibility and excluded volume. The use of the potential is computationally cheap and hence, can be used to simulate and probe complex micellar dynamics with long chains. The potential also gives a plausible method of tuning colloidal interactions in experiments such that one can obtain self-assembling polymeric chains made up of colloids and probe polymer dynamics using an optical microscope.