Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies

TL;DR

This review highlights recent bond-fluctuation model studies revealing scale-free static and dynamical correlations in polymer melts, challenging the assumption of complete screening of long-range correlations beyond the correlation length.

Contribution

It demonstrates that due to chain connectivity and incompressibility, scale-free correlations exist in polymer melts regardless of compressibility, based on simulation results.

Findings

Static and dynamical correlations extend beyond the correlation length.

Correlations are scale-free and independent of solution compressibility.

Both monodisperse and Flory-distributed polymers exhibit these correlations.

Abstract

It has been assumed until very recently that all long-range correlations are screened in three-dimensional melts of linear homopolymers on distances beyond the correlation length $\xi$ characterizing the decay of the density fluctuations. Summarizing simulation results obtained by means of a variant of the bond-fluctuation model with finite monomer excluded volume interactions and topology violating local and global Monte Carlo moves, we show that due to an interplay of the chain connectivity and the incompressibility constraint, both static and dynamical correlations arise on distances $r \gg \xi$. These correlations are scale-free and, surprisingly, do not depend explicitly on the compressibility of the solution. Both monodisperse and (essentially) Flory-distributed equilibrium polymers are considered.