Adsorption of 2d polymers with two- and three-body self-interactions

TL;DR

This study uses Monte Carlo simulations to explore how 2D polymers with complex interactions adsorb onto surfaces, revealing a rich phase diagram with multiple phases and transition types.

Contribution

It provides the first detailed phase diagram of 2D polymers with two- and three-body interactions on a lattice, including the nature of adsorption transitions.

Findings

Four distinct phases identified: swollen, globule, crystal, and adsorbed.

Adsorption transition varies between continuous and discontinuous depending on bulk phase.

No finite-temperature transition between different adsorbed layers, only a smooth crossover.

Abstract

Using extensive Monte Carlo simulations, we investigate the surface adsorption of self-avoiding trails on the triangular lattice with two- and three-body on-site monomer-monomer interactions. In the parameter space of two-body, three-body, and surface interaction strengths, the phase diagram displays four phases: swollen (coil), globule, crystal, and adsorbed. For small values of the surface interaction, we confirm the presence of swollen, globule, and crystal bulk phases. For sufficiently large values of the surface interaction, the system is in an adsorbed state, and the adsorption transition can be continuous or discontinuous, depending on the bulk phase. As such, the phase diagram contains a rich phase structure with transition surfaces that meet in multicritical lines joining in a single special multicritical point. The adsorbed phase displays two distinct regions with different characteristics, dominated by either single or double layer adsorbed ground states. Interestingly, we find that there is no finite-temperature phase transition between these two regions though rather a smooth crossover.