Scale-free center-of-mass displacement correlations in dense polymer solutions and melts without topological constraints and momentum conservation: A bond-fluctuation model study

Abstract

By Monte Carlo simulations of a variant of the bond-fluctuation model without topological constraints we examine the center-of-mass (COM) dynamics of polymer melts in $d=3$ dimensions. Our analysis focuses on the COM displacement correlation function $\CN(t) \approx \partial_t^2 \MSDcmN(t)/2$, measuring the curvature of the COM mean-square displacement $\MSDcmN(t)$. We demonstrate that $\CN(t) \approx -(\RN/\TN)^2 (\rhostar/ρ) \ f(x=t/\TN)$ with $N$ being the chain length ($16\le N\le 8192$), $\RN\sim N^{1/2}$ the typical chain size, $\TN\sim N^2$ the longest chain relaxation time, $\rho$ the monomer density, $\rhostar \approx N/\RN^d$ the self-density and $f(x)$ a universal function decaying asymptotically as $f(x)\sim x^{-\omega }$ with $\omega =(d+2)\times \alpha$ where $\alpha =1/4$ for $x\ll 1$ and $\alpha =1/2$ for $x\gg 1$. We argue that the algebraic decay $N \CN(t) \sim - t^{-5/4}$ for $t \ll \TN$ results from an interplay of chain connectivity and melt incompressibility giving rise to the correlated motion of chains and subchains.

27 pages, 12 figures

References in corpus (2)

• Intramolecular long-range correlations in polymer melts: The segmental size distribution and its moments
• A finite excluded volume bond-fluctuation model: Static properties of dense polymer melts revisited

Cited by in corpus (4)

• Scale-free static and dynamical correlations in melts of monodisperse and Flory-distributed homopolymers: A review of recent bond-fluctuation model studies
• All-atom computations with irreversible Markov chains
• Event-chain Monte Carlo with factor fields
• Note: Scale-free center-of-mass displacement correlations in polymer films without topological constraints and momentum conservation