Surface Relaxation Processes of Poly(methyl methacrylate) Brushes Prepared by Atom Transfer Radical Polymerization

Abstract

Well-defined poly(methyl methacrylate) (PMMA) brush layers were prepared onto silicon wafers by surface-initiated atom transfer radical polymerization using 2-(4-chlorosulfonylphenyl)-ethyltrichlorosilane as an initiator. Based on molecular weight and layer thickness measurements, it was deduced that the apparent graft density was 0.6–0.8 chains nm-2 depending on the polymerization time and that the conformation of tethered chains was highly extended. Surface relaxation behavior of the PMMA brush layer and the spin-coated PMMA film was examined by lateral force microscopy. The αa- and β-relaxation processes were discernibly observed at both surfaces. Although surface molecular motion of the brush layer and the spin-coated film was markedly different from the bulk one, both were hardly distinguishable in terms of relaxation phenomena.