Dynamics of micrometer-scale phase separation in a polymer mixture upon laser irradiation

TL;DR

This study investigates how laser irradiation affects micrometer-scale phase separation in a polymer mixture, revealing droplet disappearance and interface smoothing explained by Ginzburg-Landau theory with dielectric effects.

Contribution

It introduces a theoretical framework combining Ginzburg-Landau free energy with dielectric potential to describe laser-induced phase dynamics in polymer mixtures.

Findings

PEG-rich droplets shrink and vanish upon laser irradiation.

Dextran-rich droplets' interfaces broaden, indicating concentration smoothing.

The phenomena are modeled using Ginzburg-Landau free energy considering dielectric effects.

Abstract

Ten $\mu$m -sized droplets in an aqueous-two-phase system (water/ polyethylene-glycol (PEG)/ dextran) dissapear upon irradiation with a focused YAG laser. The interface of the dextran-rich droplet broadens, indicating smoothing of the concentration profile, whereas, the PEG-rich droplet shrinks and disappears. These phenomena can be described in terms of the Ginzburg-Landau free energy, by considering the laser-induced dielectric potential.