Polymer-inorganic hybrid nanoparticles via polymerization-induced self-assembly

Silica nanoparticles are commonly integrated within polymeric matrices to form composite materials, due to their non-toxic nature, chemical resistance and physical properties. Polymer-silica colloidal nanocomposites are the most studied class of hybrid nanoparticles and their applications can be tailored based on synthetic approaches. The aims of this work were to prepare polymer-silica colloidal nanocomposites via a combination of reversible deactivation radical polymerization, self-assembly and sol-gel chemistry. This approach enabled the preparation of hybrid nanoparticles with controllable shape and size. The influences of compositional design (e.g. block copolymer architecture), solvent and initiating systems were also studied. Firstly, polymer nanoparticles were prepared by Polymerization-Induced Self-Assembly (PISA) in ethanol where the solvophilic block was an alkoxysilane-functional methacrylate. Spherical nanoparticles and polymeric vesicles were successfully prepared. A solid silica shell was successfully grown from the particle surface via subsequent hydrolysis and condensation of tetraethyl orthosilicate. Secondly, block copolymer self-assembly was studied where the alkoxysilane functionality was present in the core-forming block. This approach was not viable by aqueous PISA emulsion polymerization. A solvent-mediated self-assembly approach was thus adopted, yielding spherical nanoparticles in water, and a mixture of spheres and vesicles in n-hexane. Finally, the reactivity of alkoxysilane-functional methacrylates was exploited to prepare triblock copolymers as surfactants where the interfacial block could be crosslinked via hydrolysis and condensation. Triblock copolymers were either formed separately (and used to stabilize oil-in-water miniemulsions) or in-situ via the PISA method. The encapsulation of Nile Red in the particle core was achieved in parallel with self-assembly and the retention rate was improved through interfacial crosslinking.