Impregnation of Polymers with 2,2,6,6-Tetramethyl-4-Oxo-Piperidin- -1-Oxyl (TEMPONE) Paramagnetic Probe in Suband Supercritical C0<sub>2</sub>
Spin probe method is used to investigate the impregnation of polycarbonate (PC), poly(ethylene oxide) (PEO) and cross-linked co-polymer of acrylamide and acrylic acid (PAA) with organic molecules from sub- and supercritical C0<sub>2</sub> media. The data of the electron paramagnetic resonance (EPR) spectroscopy show that paramagnetic molecules of 2,2,6,6-tetramethyl-4-oxo-piperidin-l-oxyl (TEMPONE) at 196 bar and 307 К penetrate into polymers, which are in glassy (PC) and elastic (PEO) states. In the same conditions impregnation of PAA with TEMPONE is negligible. Unlike in PEO, local concentrations of TEMPON in PC are higher than average values, thus demonstrating a much less uniform distribution of the probe in the latter polymer. Temperature variations of EPR spectra indicate that rotational mobility of probe molecules in PEO is higher than in PC. The obtained results demonstrate that the spin probe method is a promising approach to study the features of the processes on micro- and macro-levels in «polymer - supercritical solvent - organic additive» systems.