Adsorption of flexible polymer chains on a surface: Effects of different solvent conditions

TL;DR

This study uses advanced computer simulations to analyze how flexible polymer chains adsorb onto surfaces under various solvent conditions, revealing critical properties and phase diagrams for different solvent regimes.

Contribution

It introduces an efficient contact-density chain-growth algorithm to study adsorption transitions across all solvent conditions without additional simulations.

Findings

Critical exponents and transition temperatures determined

Phase diagram mapped for various solvent conditions

Finite-size-scaling methods validated for long chains

Abstract

Polymer chains undergoing a continuous adsorption-desorption transition are studied through extensive computer simulations. A three-dimensional self-avoiding walk lattice model of a polymer chain grafted onto a surface has been treated for different solvent conditions. We have used an advanced contact-density chain-growth algorithm, in which the density of contacts can be directly obtained. From this quantity, the order parameter and its fourth-order Binder cumulant are computed, as well as the corresponding critical exponents and the adsorption-desorption transition temperature. As the number of configurations with a given number of surface contacts and monomer-monomer contacts is independent of the temperature and solvent conditions, it can be easily applied to get results for different solvent parameter values without the need of any extra simulations. In analogy to continuous magnetic phase transitions, finite-size-scaling methods have been employed. Quite good results for the critical properties and phase diagram of very long single polymer chains have been obtained by properly taking into account the effects of corrections to scaling. The study covers all solvent effects, going from the limit of {\it super-self-avoiding walks}, characterized by effective monomer-monomer repulsion, to poor solvent conditions that enable the formation of compact polymer structures.