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

Research on stimuli responsive polymers builds momentum as nature-inspired applications using manmade 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-tetra-methylpiperidin-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.