Spreading Dynamics of Polymer Nanodroplets in Cylindrical Geometries

TL;DR

This study uses molecular dynamics simulations to analyze how polymer nanodroplets spread on flat surfaces in cylindrical geometries, revealing early hydrodynamic behavior and scaling laws for contact radius evolution.

Contribution

It introduces spreading models for cylindrical geometries and compares dynamics of single and multi-component polymer nanodroplets, highlighting earlier hydrodynamic behavior.

Findings

Hydrodynamic behavior appears earlier in cylindrical geometries.

Contact radius scales as t^1/5 (kinetic) and t^1/7 (hydrodynamic).

Derived spreading models analogous to spherical cases.

Abstract

The spreading of one- and two-component polymer nanodroplets is studied using molecular dynamics simulation in a cylindrical geometry. The droplets consist of polymer chains of length 10, 40, and 100 monomers per chain described by the bead-spring model spreading on a flat surface with a surface-coupled Langevin thermostat. Each droplet contains ~350,000 monomers. The dynamics of the individual components of each droplet are analyzed and compared to the dynamics of single component droplets for the spreading rates of the precursor foot and bulk croplet, the time evolution of the contact angle, and the velocity distribution inside the droplet. We derive spreading models for the cylindrical geometry analogous to the kinetic and hydrodynamic models previously developed for the spherical geometry and show that hydrodynamic behavior is observed at earlier times for the cylindrical geometry. The contact radius is predicted to scale like r(t) t^1/5 from the kinetic model and r(t) t^1/7 for the hydrodynamic model in the cylindrical geometry.