6533b821fe1ef96bd127b684

RESEARCH PRODUCT

Polymer droplets on substrates with striped surface domains: molecular dynamics simulations of equilibrium structure and liquid bridge rupture

subject

description

The structure of a polymer nanodroplet adsorbed on a flat lyophobic substrate chemically decorated with a lyophilic stripe of width 2RD is studied by molecular dynamics simulation of a coarse-grained bead–spring model of short macromolecules (containing N = 20 effective monomers). Varying the stripe width, the strength of the monomer–wall attraction and the temperature, the equilibrium morphology of the resulting droplets is studied and discussed in terms of current phenomenological theories. In the second part, the behaviour of a liquid bridge connecting two such lyophilic stripes a distance L apart is analysed. It is shown that for large enough L such free-standing films are unstable and rupture, after a hole has nucleated and grown into an elongated cavity in the lateral direction leaving only a cylindrical bridge between the stripes immediately before break-up. The forces acting between the two walls of the slit pore in equilibrium due to the thin film forming the liquid bridge are also estimated as a function of distance between the walls.