Kinetic pathways of the Nematic-Isotropic phase transition as studied by confocal microscopy on rod-like viruses

TL;DR

This study explores how rod-like viruses transition from nematic to isotropic phases, revealing that the pathway depends on concentration, with nucleation at high, spinodal decomposition at low, and a transition point at intermediate concentrations.

Contribution

It provides experimental evidence of concentration-dependent kinetic pathways in nematic-isotropic phase transitions using confocal microscopy.

Findings

High concentration leads to nucleation-and-growth

Low concentration results in spinodal decomposition

Intermediate concentration shows transition between pathways

Abstract

We investigate the kinetics of phase separation for a mixture of rodlike viruses (fd) and polymer (dextran), which effectively constitutes a system of attractive rods. This dispersion is quenched from a flow-induced fully nematic state into the region where the nematic and the isotropic phase coexist. We show experimental evidence that the kinetic pathway depends on the overall concentration. When the quench is made at high concentrations, the system is meta-stable and we observe typical nucleation-and-growth. For quenches at low concentration the system is unstable and the system undergoes a spinodal decomposition. At intermediate concentrations we see the transition between both demixing processes, where we locate the spinodal point.