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

Abstract

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 2 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 Peak Force quantitative nanomechanical mapping (QNM) mode allowed topographical verification of the spatially specific secondary brush growth and its stimulus-responsiveness.

Micrometre and nanometre scale patterning of binary polymer brushes, supported lipid bilayers and proteins

“…This was achieved by reacting the brush chain-ends with sodium azide, as described previously (step 4, Scheme 2). 21,45 This leads to replacement of each Br atom with an azide. The entire surface is then exposed to UV radiation at 325 nm (step 5), leading to removal of the remaining NPPOC protecting groups to generate surface amine sites.…”

“…37 Another approach is to form a continuous brush layer, which is then end-capped by reaction with an azide. 44,45 Exposure to UV light enables functionalization of selected regions of the surface with initiator sites, facilitating growth of a second brush. 44 Alternatively, the azide can be converted to an amine protected by a photocleavable group, allowing subsequent patterning.…”

“…44 Alternatively, the azide can be converted to an amine protected by a photocleavable group, allowing subsequent patterning. 45 Huck and co-workers described an approach based on micro-contact printing, in which a thiol-functional initiator is patterned onto a planar surface. 21 After brush growth, the initiator at the growing polymer chain-end is deactivated and a second patterning step is used to deposit initiator-terminated adsorbates in fresh regions of the surface to facilitate growth of a chemically distinct second brush layer.…”

Recent Advances in Antifouling Materials for Surface Plasmon Resonance Biosensing in Clinical Diagnostics and Food Safety

“…The modifications of PEG/OEG chains via changing the length, size, and morphology of the unit, the polymerization density, and the properties of the terminal group have been investigated to improve PEG polymers' antifouling properties [70,71].…”

Fabrication of microstructured binary polymer brush “corrals” with integral pH sensing for studies of proton transport in model membrane systems

“… 39 Recently, Chapman et al used photodeprotection chemistry in conjunction with ATRP to prepare three-dimensional two-component brushes. 40 A similar approach was used by Johnson et al to prepare two-component brushes in which one type of brush was capable of supporting lipid bilayers. 41 In addition, the preparation of complex brush structures using Iridium-catalysed, light-mediated polymerisation has been reported.…”