Chemical Modification of Polymer Brushes via Nitroxide Photoclick Trapping

• Published in: Langmuir 2013-05, Vol.29 (21), p.6369-6376
• Main Authors: Mardyukov, Artur, Li, Yong, Dickschat, Arne, Schäfer, Andreas H, Studer, Armido
• Format: Article
• Language: English
• Subjects: Chemistry; Click Chemistry; Exact sciences and technology; General and physical chemistry; Molecular Structure; Nitrogen Oxides - chemistry; Photochemical Processes; Photochemistry; Physical chemistry of induced reactions (with radiations, particles and ultrasonics); Polymerization; Polymers - chemical synthesis; Polymers - chemistry; Solid-liquid interface; Surface physical chemistry; Surface Properties
• ISSN: 0743-7463; 1520-5827
• DOI: 10.1021/la401179s

The preparation of polymer brushes (PBs) bearing α-hydroxyalkylphenylketone (2-hydroxy-2-methyl-1-phenylpropan-1-one) moieties as photoreactive polymer backbone substituents is presented. Photoreactive polymer brushes with defined thicknesses (up to 60 nm) and high grafting densities are readily prepared by surface initiated nitroxide mediated radical polymerization (SINMP). The photoactive moieties can be transformed via Norrish-type I photoreaction to surface-bound acyl radicals. Photolysis in the presence of a persistent nitroxide leads to chemically modified PBs bearing acylalkoxyamine moieties as side chains resulting from trapping of the photogenerated acyl radicals with nitroxides. Application of functionalized nitroxides to the photochemical PB postmodification provides functionalized PBs bearing cyano, polyethylene glycol (PEG), perfluoroalkyl, and biotin moieties. As shown for one case, photochemical postfunctionalization of the PB through a mask using a biotin-conjugated nitroxide as the trapping reagent leads to the corresponding site-selective chemically modified PB, which is successfully used for site-specific streptavidin immobilization. Surface analysis of PBs was performed by contact angle (CA) measurements, X-ray photoelectron spectroscopy (XPS), attenuated total reflection (ATR), fourier transform infrared (FTIR) spectroscopy, and fluorescence microscopy.