Redox-controlled upper critical solution temperature behaviour of a nitroxide containing polymer in alcohol–water mixtures

Abstract

Research on stimuli responsive polymers builds momentum as nature-inspired applications using man-made materials are increasingly sought. Here, we show for the first time the thermo-responsive upper critical solution temperature (UCST) behaviour of a nitroxide containing polymer based on (2,6,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO). It is demonstrated that poly(TEMPO methacrylate) (PTMA) exhibits a UCST-type cloud point temperature in alcohol–water mixtures that can be tuned by external electrical stimuli. To exemplify this, we studied the UCST behaviour of this polymer in alcohol–water mixtures. The reversible redox response of PTMA is used to tune the thermo-responsive behaviour of the solvated polymer. The effect of the oxidation extent in PTMA on UCST is demonstrated and a correlation between the chemical and electrochemical oxidation routes is presented.