Star polymers: A study of the structural arrest in presence of attractive interactions

TL;DR

This study explores how attractive interactions influence the structural arrest and dynamics of star polymers, revealing complex reentrant glass transitions and phase behaviors through simulations and Mode-Coupling Theory.

Contribution

It investigates the effects of attractive interactions and ultrasoft core repulsion on star polymer dynamics and glass transitions, extending understanding beyond purely repulsive models.

Findings

Reentrant melting of the disordered glass observed

Differences found compared to purely repulsive interactions

Theoretical results validated by molecular dynamics simulations

Abstract

Simulations and Mode-Coupling Theory calculations, for a large range of the arm number $f$ and packing fraction $\eta$ have shown that the structural arrest and the dynamics of star polymers in a good solvent are extremely rich: the systems show a reentrant melting of the disordered glass nested between two stable fluid phases that strongly resemble the equilibrium phase diagram. Starting from a simple model potential we investigate the effect of the interplay between attractive interactions of different range and ultrasoft core repulsion, on the dynamics and on the occurrence of the ideal glass transition line. In the two cases considered so far, we observed some significant differences with respect to the purely repulsive pair interaction. We also discuss the interplay between equilibrium and non equilibrium phase behavior. The accuracy of the theoretical tools we utilized in our investigation has been checked by comparing the results with molecular dynamics simulations.