Spreading Dynamics of Polymer Nanodroplets in Cylindrical Geometries

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.