Redox Active Polymer Brushes with Phenothiazine Moieties

We have investigated two different concepts to synthesize redox active polymer brushes using surface initiated atomic transfer radical polymerization (SI-ATRP). This polymerization technique allows the synthesis of well-defined grafted polymer brushes. In the initial step the surface was functionalized with a self-assembling monolayer of the SI-ATRP starter. Then, polymer brushes carrying phenothiazine moieties were grafted from the surface via SI-ATRP. The first concept consists of polymerizing monomers with phenothiazine pendant moieties to directly incorporate the redox functionality as side group in the growing polymer brush. The second concept consists of using grafted activated ester brushes which are functionalized with phenothiazine redox moieties in a successive reaction step. The electrochemical properties of the grafted redox active brushes were examined by cyclic voltammetry. Furthermore, the surface morphology and the chemical composition of the polymer brushes were characterized using scanning force microscopy (SFM), X-ray techniques, and UV/vis spectroscopy. Apart from their redox behavior, the synthesized brushes revealed increased mechanical stability on the nanoscale.