Controlled Grafting of Well-Defined Polymers on Hydrogen-Terminated Silicon Substrates by Surface-Initiated Atom Transfer Radical Polymerization

Abstract

Controlled grafting of well-defined polymer brushes on the hydrogen-terminated Si(100) substrates (the Si−H substrate) was carried out via the surface-initiated atom transfer radical polymerization (ATRP). Surface initiators were immobilized on the Si−H substrates in three consecutive steps: (i) coupling of an ω-unsaturated alkyl ester to the Si−H surface under UV irradiation, (ii) reduction of the ester groups by LiAlH4, and (iii) esterification of the surface-tethered hydroxyl groups with 2-bromoisobutyrate bromide. Homopolymer brushes of methyl methacrylate (MMA), (2-dimethylamino)ethyl methacrylate (DMAEMA), and poly(ethylene glycol) monomethacrylate (PEGMA) were prepared by ATRP from the α-bromoester functionalized silicon surface. The chemical composition and topography of the graft-functionalized silicon surfaces were characterized by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. Kinetic studies revealed a linear increase in polymer film thickness with rea...