Adsorption of Multi-block and Random Copolymer on a Solid Surface: Critical Behavior and Phase Diagram

TL;DR

This study investigates the critical adsorption behavior of multi-block and random copolymers on solid surfaces using simulations and scaling analysis, revealing how polymer structure influences adsorption properties.

Contribution

It introduces a mapping of copolymer adsorption to an effective homopolymer problem and validates predictions with two different Monte Carlo simulation methods.

Findings

Critical adsorption energy depends on block length and total chain length.

Random copolymer adsorption is well described by the annealed approximation.

Simulation results agree with theoretical predictions across methods.

Abstract

The adsorption of a single multi-block $AB$-copolymer on a solid planar substrate is investigated by means of computer simulations and scaling analysis. It is shown that the problem can be mapped onto an effective homopolymer adsorption problem. In particular we discuss how the critical adsorption energy and the fraction of adsorbed monomers depend on the block length $M$ of sticking monomers $A$, and on the total length $N$ of the polymer chains. Also the adsorption of the random copolymers is considered and found to be well described within the framework of the annealed approximation. For a better test of our theoretical prediction, two different Monte Carlo (MC) simulation methods were employed: a) off-lattice dynamic bead-spring model, based on the standard Metropolis algorithm (MA), and b) coarse-grained lattice model using the Pruned-enriched Rosenbluth method (PERM) which enables tests for very long chains. The findings of both methods are fully consistent and in good agreement with theoretical predictions.