Surface-induced First Order Transition in Athermal Polymer/Nanoparticle Blends

TL;DR

This study uses density functional theory to reveal a first order surface phase transition in athermal polymer/nanoparticle blends, driven by entropic effects, explaining experimental observations.

Contribution

It demonstrates a first order surface transition in polymer/nanoparticle blends using a theoretical approach, linking entropy to surface behavior.

Findings

Nanoparticles form a monolayer by expelling polymer at the surface.

Transition density varies with polymer length and bulk density.

The phenomenon is driven by packing and configurational entropy.

Abstract

We investigate the phase behavior of athermal polymer/nanoparticle blends near a hard substrate. We apply the density functional theory of Tripathi and Chapman to these blends. We find a first order phase transition where the nanoparticles expel the polymer from the surface to form a monolayer. The transition density depends on the polymer length and the system bulk density. The effect is due to the packing entropy of the species and configurational entropy of the polymer. The simplicity of the system allows us to understand the so-called ``entropic-push'' observed in experiments.