We recently reported the synthesis of a new hydrophilic cis-diol-based monomer (GEO5MA) that can be oxidized under mild conditions using sodium periodate to give a new water-soluble aldehyde-functional monomer (AGEO5MA). This chemistry can also be performed on the corresponding homopolymer (PGEO5MA) to convert it into PAGEO5MA. Herein, we exploit the same chemistry for the synthesis of aldehyde-functional hydrophilic polymer brushes. GEO5MA monomer is polymerized from a planar silicon substrate using surface-initiated Activators ReGenerated by Electron Transfer Atom Transfer Radical Polymerization (ARGET ATRP). Ellipsometry studies confirmed that dry PGEO5MA brush thicknesses of up to 100 nm could be achieved within 2 h at 22 °C. An aqueous solution of sodium periodate was used to oxidise the pendent cis-diol groups at 22 °C. The resulting aldehyde-functional PAGEO5MA brushes were reacted in turn with several primary amines, e.g. histidine, 2,2,2-trifluoroethylamine or (2-aminoethyl)trimethylammonium chloride hydrochloride (AETMA), followed by treatment with NaCNBH3. Surface zeta potential and XPS studies on the histidine- and AETMA-functionalized brushes confirmed the expected change in surface structure after reductive amination. This new brush system should enable facile conjugation of proteins or enzymes in aqueous solution at ambient temperature.

New aldehyde-functional hydrophilic polymer brushes: Synthesis, characterization and potential bioapplications

ACS Spring 2022

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