Spatial Organization of Nanoparticles in Thin Film Block Copolymer/Homopolymer Hosts

Polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) diblock copolymers (BCP) form spherical micelles, wherein each micelle is composed of an inner core of the P2VP block and an outer corona of the PS block of BCP, within thin film PS homopolymer hosts. The spatial distribution of PS-grafted gold nanoparticles (PS-Au NPs) within this thin film BCP/homopolymer system is characterized by a morphological diagram of the curvature of the Au cores 1/R-C vs the degree of polymerization N of the grafted PS chains. Five basic morphological regimes, largely dictated by competing entropic and enthalpic intermolecular interactions, characterize the distribution of nanoparticles. The NP distributions include one case wherein the NPs reside primarily at the external interfaces (free surface and substrate) and another where the nanopartides preferentially "decorate" the surfaces of the micelles. The existence of these different regimes is rationalized in terms of various competing short- and long-range intermolecular interactions.