Importance of Polymer Ligand Conformation to the Entropy-Driven Assembly Behavior of Polymer-Grafted Nanoparticles within 3D-Confined Block Copolymers

Abstract

Assembly of hybrid materials with well-defined morphologies is important to design nanomaterials. Here we show a design of entropy-driven particle assemblies with polystyrene-grafted Au nanoparticles (Au@PS) within onion-like polystyrene-b-poly (4-vinylpyridine) (PS-b-P4VP) block copolymer (BCP) particles. Four parameters are investigated: molecular weight (N) and grafting density of PS ligands, core size of Au@PS, and Mn of PS blocks (P). We observed transitions of hybrid particles from alternate-layered onions to crusted onions by controlling these parameters. To account for the phenomena, a modified swelling ratio (P/NSDPB) is proposed by considering the ligands in semi-dilute polymer brush (SDPB) regime as the only brushes available for interfacial interactions with BCPs. The modified parameter successfully explains structural transitions. The findings well demonstrated the importance of ligand conformation to the entropic interactions between block copolymers and grafted polymers.