Depletion effects in colloid-polymer solutions

TL;DR

This study uses Monte Carlo simulations to analyze depletion effects of polymers near colloidal spheres, validating theoretical predictions across different solvent conditions and polymer concentrations.

Contribution

It provides comprehensive simulation data on depletion phenomena in colloid-polymer solutions, confirming theoretical scaling and field-theoretical results under various conditions.

Findings

Good agreement with theoretical predictions

Validation of scaling arguments in dilute and semidilute regimes

Accurate computation of surface tension, adsorption, and depletion thickness

Abstract

The surface tension, the adsorption, and the depletion thickness of polymers close to a single nonadsorbing colloidal sphere are computed by means of Monte Carlo simulations. We consider polymers under good-solvent conditions and in the thermal crossover region between good-solvent and $\theta$ behavior. In the dilute regime we consider a wide range of values of $q$, from $q = 0$ (planar surface) up to $q\approx 30$-50, while in the semidilute regime, for $\rho_p/\rho_p^*\le 4$ ($\rho_p$ is the polymer concentration and $\rho_p^*$ is its value at overlap), we only consider $q = 0,0.5,1$ and 2. The results are compared with the available theoretical predictions, verifying the existing scaling arguments. Field-theoretical results, both in the dilute and in the semidilute regime, are in good agreement with the numerical estimates for polymers under good-solvent conditions.