Capillary Wave Confinement-Induced Stabilization of Polymer Films

We show that temporary confinement of polystyrene thin films by an elastomeric capping layer possessing nanoimprinted subcapillary wavelength (λ ≪ λ_cap (20 μm)) line channels (amplitude A ≈ 120 nm) can suppress film dewetting on thermodynamically unfavorable substrates by arresting the amplitude growth and in-plane propagation of the destabilizing surface capillary waves. Confinement by either a smooth elastomer capping layer (A ≈ 1 nm) or with pattern features above the threshold dimension only retards dewetting but does not prevent it. The nanoimprint pattern is therefore essential to preventing dewetting, illustrating that only the penalty of elastomer deformation and interfacial tension reduction is insufficient.