Effect of confinement on coil-globule transition

TL;DR

This study investigates how confinement between two walls affects the thermodynamic behavior and coil-globule transition of a linear polymer, revealing non-monotonic size behavior and re-entrant transition phenomena.

Contribution

It provides a detailed analysis of the effects of confinement on polymer transition temperatures and conformations using series analysis and enumeration techniques.

Findings

End-to-end distance shows non-monotonic dependence on wall separation.

Collapse transition temperature increases near specific wall distances.

Re-entrant behavior observed in theta-temperature variation with confinement.

Abstract

The equilibrium thermodynamic properties of a linear polymer chain confined to a space between two impenetrable walls (lines) at a distance $D$ under various solvent conditions have been studied using series analysis and exact enumeration technique. We have calculated the end to end distance of polymer chain, which shows a non-monotonic behaviour with inter wall ^M separation $D$. The density distribution profile shows a maxima at a particular value of ${(D=)}D^*$. Around this $D^*$, our results show that the collapse^M transition occurs at higher temperature as compared to its bulk value of 2d and 3d. The variation of $\theta-$ temperature with $D$ shows a re-entrance behaviour. We also calculate the force of compression exerted by the walls (lines) on the polymer.