Fabrication of Two-Component, Brush-on-Brush Topographical Microstructures by Combination of Atom-Transfer Radical Polymerization with Polymer End-Functionalization and Photopatterning

摘要

Poly(oligoethylene glycol methyl ether methacrylate) (POEGMEMA) brushes, grown from silicon oxide surfaces by surface-initiated atom transfer radical polymerization (SI-ATRP), were end-capped by reaction with sodium azide leading to effective termination of polymerization. Reduction of the terminal azide to an amine, followed by derivatization with the reagent of choice, enabled end-functionalization of the polymers. Reaction with bromoisobutryl bromide yielded a terminal bromine atom that could be used as an initiator for ATRP with a second, contrasting monomer (methacrylic acid) Attachment of a nitrophenyl protecting group to the amine facilitated photopatterning: when the sample Was exposed to UV light through a mask, the amine was deprotected in exposed regions, enabling selective bromination and the growth of a patterned brush by ATRP. Using this approach, micropatterned pH-responsive poly(Methacrylic acid) (PMAA) brushes were grown on a protein resistant planar poly(oligoethylene: glycol methyl ether methacrylate) (POEGMEMA) brush. Atomic force microscopy analysis by tapping mode and PeakForce quantitative, nanomechanical mapping (QNM) mode allowed topographical-verification of spatially specific secondary brush growth and its stimulus responsiveness. Chemical confirmation of selective polymer growth was achieved by secondary ion mass spectrometry (SIMS).