Theoretical Approaches to Neutral and Charged Polymer Brushes

TL;DR

This paper reviews theoretical models and simulation methods for understanding the structure and behavior of neutral and charged polymer brushes on planar surfaces, emphasizing differences due to electrostatic effects.

Contribution

It compares scaling models, self-consistent-field methods, and MD simulations to analyze neutral and charged polymer brushes, highlighting the impact of electrostatics on brush swelling.

Findings

Self-consistent calculations accurately predict brush height and density profiles.

Charged polymers exhibit strong, non-linear swelling due to counterion effects.

Electrostatic interactions significantly influence polyelectrolyte brush behavior.

Abstract

Neutral or charged polymers that are densely end-grafted to surfaces form brush-like structures and are highly stretched under good-solvent conditions. We discuss and compare relevant results from scaling models, self-consistent-field methods and MD simulation techniques and concentrate on the conceptual simple case of planar substrates. For neutral polymers the main quantity of interest is the brush height and the polymer density profile, which can be well predicted from self-consistent calculations and simulations. Charged polymers (polyelectrolytes) are of practical importance since they are soluble in water. Counterion degrees of freedom determine the brush behavior in a decisive way and lead to a strong and non-linear swelling of the brush.