Effective interactions between star polymers

TL;DR

This study uses advanced simulations to accurately determine the effective pair potential between star polymers, revealing it to be less soft than previously thought, especially for high arm numbers, and confirming the logarithmic divergence predicted by theory.

Contribution

The paper provides a more precise numerical analysis of star polymer interactions, challenging prior assumptions about the softness of the potential for large arm numbers.

Findings

Potential is less soft than previously claimed for large f

Logarithmic divergence of V(r) confirmed

Mayer function resembles Gaussian potential for f>20

Abstract

We study numerically the effective pair potential between star polymers with equal arm lengths and equal number $f$ of arms. The simulations were done for the soft core Domb-Joyce model on the simple cubic lattice, to minimize corrections to scaling and to allow for an unlimited number of arms. For the sampling, we used the pruned-enriched Rosenbluth method (PERM). We find that the potential is much less soft than claimed in previous papers, in particular for $f\gg 1$. While we verify the logarithmic divergence of $V(r)$, with $r$ being the distance between the two cores, predicted by Witten and Pincus, we find for $f>20$ that the Mayer function is hardly distinguishable from that for a Gaussian potential.