Redox active polymers with phenothiazine moieties for nanoscale patterning via conductive scanning force microscopy

Abstract

Redox active polymers with phenothiazine moieties have been synthesized by Atomic Transfer Radical Polymerization (ATRP). These novel polymers reveal bistable behaviour upon application of a bias potential above the oxidation threshold value. Using conductive Scanning Force Microscopy, two distinguishable conductivity levels were induced on a nanoscale level. These levels were related to a high conducting “On” and a low conducting “Off” state. The “On” state is generated by the oxidation of the phenothiazine side chains to form stable phenothiazine radical cations. The formation and stability of the radical sites was examined by cyclic voltammetry, electron spin resonance and optical spectroscopy. Polymers with phenothiazine moieties show the ability to retain their redox state for several hours and can therefore be used for nonvolatile organic memory devices. Furthermore, thin films made from the phenothiazine containing polymers show high mechanical nanowear stability.