Hybrid Inorganic Organic Diblock Copolymers Nanostructure In Polyhedral Oligomeric Silsesquioxane Polymorbornenes PDF Download

Supramolecular structures formed by the spontaneous self-assembly of block copolymers in selective solvents have been the focus of academic interest over the last decade. The recent development of "living radical polymerization" synthesis methods has expanded the range of functional block polymers and improve the controllability of block length,6−10 which lead spherical polymer micelles and nanoparticles into significant potential in application. However, the spontaneous dissociation of micelles under their critical micelle concentration (CMC) always limits further applications.18,19,22 Later, the emergence of cross-linked micelle solved this problem.21 By cross-linking the core or shell of micelle, it leads to the formation of robust nanoparticles, which prevent the dissociation below CMC.21,22 In this work, to explore new and efficient crosslink strategy, stable spherical inorganic-organic hybrid micelles were prepared by covalent crosslinking of micellar core/interface, via thiol-ene click chemistry. Amphiphilic block copolymer, poly(ethylene oxide)-block-polystyrene with vinyl-funcitonalized polyhedral oligomeric silsesquioxanes (VPOSS) randomly distributed on the PS block (PEO-b-PS/VPOSS), was designed to form the core-crosslinked micelles by self assembly in a mixture of dimethylformamide (DMF) and water with PS/VPOSS as core and PEO as corona. Meanwhile, another polymer, PEO-b-PS with a VPOSS precisely located at the junction point of two blocks was synthesized to form the interfacial crosslinked micelles with VPOSS nanoparticles distributed on the interface between micellar core and shell in DMF/water solution. The stability of the micelles were greatly enhanced by crosslinking of vinyl groups on VPOSS moieties under UV irradiation with pentaerythritol tetrakis(3-mercaptobutylate) as crosslinking agent. The process is fast, efficient, and environmental tolerant. The crosslinked micelles can sustain their spherical morphology in organic solvent. The self assembly and crosslinking process were fully studied by Dynamic Light Scattering (DLS), and Transmission Electron Microscopy (TEM).