Preparation and Morphology of Hybrids Composed of a Block Copolymer and Semiconductor Nanoparticles via Hydrogen Bonding

Abstract

We report a systematic study on preparation and morphological observation of hybrids composed of a block copolymer and hydroxy-capped semiconductor nanoparticles via hydrogen bonding. Three polystyrene-b-poly(4-vinylpyridine) (PS–P4VP) block copolymers with exactly the same PS chain length but with different P4VP chain length were synthesized via reversible addition–fragmentation chain transfer polymerization. To prepare hybrids, each PS–P4VP was mixed with hydroxy-capped nanoparticles made of cadmium selenide (h-CdSe), by varying a weight ratio of PS–P4VP:h-CdSe. Morphology of three series of hybrids was observed by both transmission electron microscopy and small-angle X-ray scattering. Hybrids composed of h-CdSe and PS–P4VP bearing a long P4VP block represents uniform morphology of a single nanophase-separated structure, where domain spacing expansion and morphology transition induced by addition of h-CdSe were observed. On the other hand, nonuniform morphology, i.e., macrophase separation accompanied by overflow of h-CdSe from nanophase-separated domains, was observed in hybrids containing PS–P4VP bearing a short P4VP block. These results are attributed to hydrogen-bonding formation and the stoichiometric balance of functional groups.