Microgel/SiO2 hybrid colloids prepared using a water soluble silica precursor

In the present work we demonstrate that functional polymer microgels may act as smart self-catalyzing system inducing controlled formation of silica nanoparticles inside the polymer network and formation of hybrid colloids. We synthesized a water soluble silica precursor PEG-PEOS via post-modification of hyperbranched poly(ethoxysiloxane) (PEOS) with poly(ethylene glycol) monomethyl ether. We used poly(N-vinylcaprolactam)-based microgel functionalized with imidazole and β-diketone groups as a matrix for biomimetic deposition of silica. Composite microgel particles containing silica nanoparticles (up to 20 wt.-%) have been prepared by simultaneous PEG-PEOS conversion and silica deposition in the microgels. TEM studies indicate the infiltration of silica nanoparticles (∼10 nm) inside the corona region of the microgels due to the strong acid-base interaction between the acidic silica and basic imidazole groups. The resulting composite particles were found to be colloidally stable and no aggregation was observed even after months of storage. The incorporation of silica nanoparticles increased the rigidity of the microgel particles and reduced their thermal sensitivity.