Conformational Mechanics of Polymer Adsorption Transitions at Attractive Substrates

TL;DR

This study uses multicanonical simulations to explore the phase behavior of semiflexible polymers near attractive surfaces, revealing various conformational phases and phase transitions including adsorption, desorption, and freezing.

Contribution

It introduces a detailed phase diagram for polymer adsorption that accounts for solvent effects and identifies multiple phase transitions beyond simple adsorption/desorption.

Findings

Identification of adsorbed and desorbed phases.

Discovery of a freezing transition between crystalline and globular states.

Construction of a solubility-temperature phase diagram.

Abstract

Conformational phases of a semiflexible off-lattice homopolymer model near an attractive substrate are investigated by means of multicanonical computer simulations. In our polymer-substrate model, nonbonded pairs of monomers as well as monomers and the substrate interact via attractive van der Waals forces. To characterize conformational phases of this hybrid system, we analyze thermal fluctuations of energetic and structural quantities, as well as adequate docking parameters. Introducing a solvent parameter related to the strength of the surface attraction, we construct and discuss the solubility-temperature phase diagram. Apart from the main phases of adsorbed and desorbed conformations, we identify several other phase transitions such as the freezing transition between energy-dominated crystalline low-temperature structures and globular entropy-dominated conformations.