From concentration profiles to polymer osmotic equations of state

TL;DR

This paper introduces a simulation-based method to determine the osmotic equation-of-state of polymer solutions by analyzing concentration profiles under gravity, applicable across various solvent conditions.

Contribution

The authors present a novel approach using Monte Carlo simulations of concentration profiles to accurately derive polymer osmotic equations of state over wide concentration ranges.

Findings

Method provides full equation of state from a single simulation.

Accurate across different solvent qualities from good to theta conditions.

Minimal finite size effects observed in the approach.

Abstract

We show that equilibrium monomer and centre-of-mass concentration profiles of lattice polymers in a gravitational field, computed by Monte-Carlo simulations, provide an accurate and efficient road to the osmotic equation-of-state of polymer solutions, via a straightforward application of the hydrostatic equilibrium condition. The method yields the full equation of state over a wide range of concentrations from a single simulation, and does not suffer from significant finite size effects. It has been applied to self-avoiding walk polymer chains with nearest neighbour monomer attractions, from the good solvent to the theta solvent regimes. The consistency of the method has been carefully checked by varying the strength of the gravitational field.