(65l) Optimization of Atom Transfer Radical Polymerization From Silica Nanoparticles

Polymer nanocomposites (PNCs) are used widely in coatings, optics, catalysis, and plastics. Uniform dispersion of nanoparticles within the polymer melt is desired for control of material properties including strength, hardness and thermal and electrical conductivity. Grafting polymer chains from particle surfaces is a practiced technique to prevent aggregation of particles, and thus, promote particle dispersion. Atom transfer radical polymerization (ATRP) is a specialized reaction scheme to obtain high graft densities of polymer brushes. Improved engineering control of ATRP is needed to create well-defined, dense polymer brushes from nanoparticles to ultimately improve nanoparticle dispersion within PNCs.

Our goal is to optimize ATRP reaction conditions of methyl methacyrlate (MMA) from silica nanoparticles to achieve polymer brushes of high graft density, low polydispersity, and well-controlled molecular weight of the polymer brush. To this end, the effect of ligand, metal catalyst, particle concentration, and temperature were investigated. Characterization techniques of gas chromatography (GC), gel permeation chromatography (GPC), and thermal gravimetric analysis (TGA) were used to quantify the reaction kinetics, molecular weight, and graft density. Ultimately, optimizing reaction conditions of ATRP to form dense, uniform polymer brushes on nanoparticle surfaces enables control of particle interactions and fine-tuning of material properties of PNCs.