SCF impregnation of polymer matrices with stable nitroxyl radicals

The ESR method is used to study the impregnation of a set of polymer matrices (co-polymer F-42, polyvinylchloride, polycarbonate, polymethylmethacrylate) with stable nitroxyl radicals of 2,2,6,6-tetramethyl-4-oxypiperidin-1-oxyl (TEMOPO) in a supercritical carbon dioxide medium. The amount of the substance incorporated into the polymer matrices increases with increase of the mass of TEMOPO samples used and converges to the limit values that for F-42 and polyvinylchloride samples are 9.6 × 10²⁰ and 7.5 × 10²⁰ paramagnetic centers per gram of the polymer, respectively. At the same time, no formation of TEMOPO clusters is observed; the spatial distribution of radicals absorbed by the polymer film is close to random and is independent from the film thickness.