(743b) Impact of Mixed Initiator Monolayers On the ATRP of Polystyrene From Silica Nanoparticle Surfaces

Controlling the distribution of functional groups on a material surface offers the opportunity to tailor complex systems for applications including responsive materials, superhydrophobic surfaces and environmental remediation. Most work with controlling the phase separation of mixed monolayers on surfaces has been conducted on gold while phase separation on silica surfaces has remained largely untouched. A system of mixed monolayers was prepared to control the density of polymers grafted from silica nanoparticle surfaces. An ATRP initiator containing an ester linkage was mixed with its inert analog containing an amide linkage. These were reacted to the nanoparticle surface in different ratios and the products were characterized with elemental analysis. The inert analog was found to be the predominant species on the particle surface regardless of reaction ratio. ATRP polymerizations conducted from the particle surface resulted in lower initiator efficiencies than expected for the mixed monolayer systems. NMR was used to characterize the reaction solution, and the mixed monolayer systems were further investigated with FTIR, which provided evidence of phase separation. Finally the monolayer structure was studied with AFM.