Phase diagram for a single flexible Stockmayer polymer at zero field

TL;DR

This study explores the equilibrium shapes of a magnetic polymer chain with Lennard-Jones interactions, revealing complex phases and unique features like multiple triple points through Langevin dynamics simulations.

Contribution

It provides the first detailed phase diagram for a flexible magnetic chain, highlighting novel conformational phases not seen in non-magnetic polymers.

Findings

Identification of multiple unusual conformational phases

Presence of at least two triple points in the phase diagram

Discovery of highly anisotropic, helicoidal, and collapsed states

Abstract

The equilibrium conformations of a flexible permanent magnetic chain that consists of a sequence of linked magnetic colloidal nanoparticles with short-ranged Lennard-Jones attractive interactions (Stockmayer polymer) are thoroughly analysed via Langevin dynamics simulations. A tentative phase diagram is presented for a chain of length $N=100$. The phase diagram exhibits several unusual conformational phases when compared with the non-magnetic chains. These phases are characterised by a large degree of conformational anisotropy, and consist of closed chains, helicoidal-like states, partially collapsed states, and very compact disordered states. The phase diagram contains several interesting features like the existence of at least two 'triple points'.