Molecular Dynamics Simulation of Semiflexible Polyampholyte Brushes - The Effect of Charged Monomers Sequence

TL;DR

This study uses molecular dynamics simulations to explore how the sequence of charged monomers in semiflexible polyampholyte brushes affects their structure and behavior under different conditions.

Contribution

It investigates the impact of charged monomer sequence on brush properties, revealing how block length influences thickness, conformation, and inter-chain bonding.

Findings

Longer charged blocks lead to smaller brush thickness.

Brush properties are more sensitive to grafting density and salt concentration with longer blocks.

Chains tend to bond or buckle depending on grafting density and charge sequence.

Abstract

Planar brushes formed by end-grafted semiflexible polyampholyte chains, each chain containing equal number of positively and negatively charged monomers is studied using molecular dynamics simulations. Keeping the length of the chains fixed, dependence of the average brush thickness and equilibrium statistics of the brush conformations on the grafting density and the salt concentration are obtained with various sequences of charged monomers. When similarly charged monomers of the chains are arranged in longer blocks, the average brush thickness is smaller and dependence of brush properties on the grafting density and the salt concentration is stronger. With such long blocks of similarly charged monomers, the anchored chains bond to each other in the vicinity of the grafting surface at low grafting densities and buckle toward the grafting surface at high grafting densities.