Microgel/silica hybrid colloids: Bioinspired synthesis and controlled release application

Abstract

In the present work, we demonstrate that polymer based functional microgels can be used as autocatalytic template for the bioinspired deposition of silica nanoparticles inside the microgel network under ambient conditions. Temperature responsive poly(N-vinyl caprolactam) based microgels were synthesized by precipitation polymerization using glycidyl methacrylate as a comonomer. These microgels were further reacted with aminoethanthiol to develop amine functional groups inside the microgels. A water soluble silica precursor (PEGPEOS) was developed by modification of hyperbranched polyethoxysiloxane with polyethylene glycol monomethyl ether. Microgel/silica hybrid colloids were prepared by simultaneous PEGPEOS conversion and silica deposition in the microgels. TEM studies showed that silica nanoparticles of approximately 10 nm in size were deposited inside the microgel network owing to the strong acidbase interaction between the acidic silica and basic amine groups. DLS results indicated that the incorporation of silica nanoparticles reduced the thermal sensitivity of microgels. Molecular dynamics simulations were performed to investigate the interaction between silica precursor and microgels based on radial distribution function and interaction energy. The developed hybrid microgels were further explored for controlled release of aspirin used as a model drug. The preliminary results indicated that the presence of silica rich domains in the microgel network remarkably retarded aspirin release.