Surface-Attached Poly(glycidyl methacrylate) as a
Versatile Platform for Creating Dual-Functional Polymer Brushes
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Abstract
Novel
types of dual-functional surface-attached polymer brushes
were developed by post-polymerization modification of poly(glycidyl
methacrylate) brushes on glassy carbon substrates. Azide and alcohol
groups were initially introduced by epoxide ring-openings of the side
chains. These polymer brushes represent an attractive chemical platform
to deliberately introduce other molecular units at specific sites.
In this work, ferrocene and nitrobenzene redox units were immobilized
through the two groups to create redox polymers. In-depth analysis
by infrared reflection–absorption spectroscopy and X-ray photoelectron
spectroscopy revealed an almost quantitative conversion of the modification
reactions. The electrochemical activity of the ferrocenyl part of
this diode-like system was fully expressed with an electron transfer
rate constant = 1.2 s<sup>–1</sup> and surface density = 0.19
nmol cm<sup>–2</sup> per nm section of the film, independent
of its thickness. In contrast, for the nitrobenzene moieties diffusion
of counterions (i.e., tetraalkylammonium) easily becomes the rate-controlling
step, thereby leaving a substantial fraction of them electrochemically
inactive