Supramolecular structures of alternative polymer-nanoparticle hybrids

Through covalently bonding polymer blocks with small-size nanoparticles, the alternative polymer-nanoparticle hybrids can assemble into unprecedented supramolecular nanostructures due to the interparticle interactions. In this contribution, we investigate the formation of the supramolecular structure of linear alternating polystyrene (PS)-polyhedral oligomeric silsesquioxane (POSS) polymer hybrids (LAPH), through a combination of small-angle x-ray scattering (SAXS) and rheology. Clear clustering with average sizes of 2-8 POSS particles is observed through SAXS, confirming the strong tendency for nanoparticle aggregation. The linear rheology shows a very weak modulus plateau at the intermediate time scale and clear evidence of gelation at the long-time limit. Importantly, the modulus plateau is much smaller than the prediction of intra-chain nanoparticle association, implying the formation of inter-connected flower-like supramolecular structures of LAPH. These observations highlight nanoparticle-nanoparticle association as an alternative way to control the nanostructure formation.