Spreading Dynamics of Polymer Nanodroplets

TL;DR

This study uses large-scale molecular dynamics simulations to analyze the spreading behavior of polymer nanodroplets, revealing diffusive precursor foot dynamics and confirming the molecular kinetic model without hydrodynamic effects.

Contribution

It provides new insights into polymer droplet spreading by simulating large systems and comparing different surface types and chain lengths, confirming the diffusive nature of precursor foot movement.

Findings

Precursor foot exhibits diffusive spreading behavior.

Good agreement with the molecular kinetic model.

No evidence of hydrodynamic effects in large droplets.

Abstract

The spreading of polymer droplets is studied using molecular dynamics simulations. To study the dynamics of both the precursor foot and the bulk droplet, large drops of ~200,000 monomers are simulated using a bead-spring model for polymers of chain length 10, 20, and 40 monomers per chain. We compare spreading on flat and atomistic surfaces, chain length effects, and different applications of the Langevin and dissipative particle dynamics thermostats. We find diffusive behavior for the precursor foot and good agreement with the molecular kinetic model of droplet spreading using both flat and atomistic surfaces. Despite the large system size and long simulation time relative to previous simulations, we find no evidence of hydrodynamic behavior in the spreading droplet.