Silica‐PMMA hairy nanoparticles prepared via phase transfer‐assisted aqueous miniemulsion atom transfer radical polymerization

Hairy nanoparticles (HNPs) constitute a class of hybrid nanocomposites that are resistant to aggregation and agglomeration, although the green, large‐scale synthesis of HNPs remains a challenge. In this work, 25 nm‐diameter silica‐core HNPs with a poly(methyl methacrylate) (PMMA) shell were synthesized using a graft‐from approach in aqueous miniemulsion, employing atom transfer radical polymerization with activators regenerated by electron transfer (ARGET‐ATRP). In particular, this work used tetrabutylammonium bromide (TBAB)‐assisted phase transfer of monomer, markedly improving upon earlier methods by showing that phase transfer could take place in the absence of organic solvents. Furthermore, syntheses with selected monomer addition rates produced HNP graft densities ranging from 0.011 to 0.017 chains/nm2 and shell thicknesses ranging from 2.5 to 11 nm. Finally, analysis of reaction kinetics revealed that shell growth reached completion in as little as 2 hr, confirmed by the synthesis of >1 g of PMMA‐shell HNPs in a reduced timeframe. Hairy nanoparticles (HNPs) were synthesized in aqueous miniemulsion by polymerizing methyl methacrylate (MMA) from silica nanoparticle surfaces. Earlier techniques involving ARGET‐ATRP with a phase transfer catalyst are improved, leading to the gram‐scale synthesis of HNPs with controllable shell thickness and graft density.