Inorganic nanoparticle-blended polymer nanofilm and its wettability improvement: Film grading and dewetting cause analysis

Abstract

Dewetting of polymer thin film coated on a solid substrate at higher temperature than the glass transition is one of the major problems restricting its functionality. While nanoparticle inclusion is considered as a simple but effective solution, influence of directly measurable film characteristics on polymer chain dynamics has been a crucial topic. Here, using dynamic atomic force microscopy (DAFM)-based nano mechanical analysis, we present a systematic investigation of inorganic nanoparticle-filled polymeric nanofilms designed for heat-resistant coating based on pinning effect of the interfacial nanoparticle layer by varying concentrations of the zinc oxide (ZnO) nanofiller and the polystyrene (PS) polymer. Performing morphological analysis from dewetting hole occurrence and surface roughness together with size and distribution of the protruding surface aggregates, not only dewetting and non-dewetting films are distinguished, but also the optimal film can be identified. Dewetting suppression mechanism has been proposed on the basis of height profiles of individual dewetting holes, relative interfacing energies, and relation between local stiffness and polymeric chain crowding, suggesting effect from polymeric canopies incorporated with the nanoparticles. This work sheds more light on improving the thermal-proof coating and provides a general protocol for film grading and dewetting inspection at the nanoscale.