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A facile method of forming nanoscale patterns on poly(ethylene glycol)-based surfaces by self-assembly of randomly grafted block copolymer brushes.

Poly(oligo(ethylene glycol) methacrylate) (POEGMA) block poly(methyl methacrylate) (PMMA) brushes were synthesized on the silicon wafer surfaces by the surface-initiated atom transfer radical polymerization (ATRP) method. Atomic force microscopy, ellipsometry, and water contact angle methods were employed to study the surface morphology and stimulus-response behavior. It was found that simple solvent treatments could induce phase segregation of the POEGMA and PMMA segments thus introducing nanoscale patterns. The feature size could be less than 10 nm and was tunable on the nanoscale. Various patterns including spherical aggregates, wormlike aggregates, stripe patterns, perforated layers, and complete overlayers were obtained through adjusting the upper block layer thickness. These patterns could switch between the different morphologies reversibly after the treatment with selective solvents.