Wetting Behavior of Homopolymer Films on Chemically Similar Block Copolymer Surfaces

Abstract

The wetting properties of thin polystyrene (PS) homopolymer films (polymerization index ${N}_{H}$) were studied on the surfaces of polyvinylpyridine-polystyrene (PVP-PS) block copolymer films (polymerization indices ${N}_{\mathrm{PS}}$ and ${N}_{\mathrm{PVP}}$) oriented into lamellae with the PS block present at the vacuum interface. Autodewetting was observed on the diblock copolymer surface when $\frac{{N}_{H}}{{N}_{\mathrm{PS}}}\ensuremath{\ge}5$, with a contact angle independent of ${N}_{H}$, but decreasing with N. The dewetting nucleated at the base of islands on the ordered PVP-PS surfaces. The dewetting processes were explained using mean field theories and Monte Carlo simulations.