Impregnation of Polymethyl Methacrylate with Carbamazepine in Supercritical Carbon Dioxide

Two polymethyl methacrylate (PMMA) samples are impregnated with carbamazepine (CBZ) in a supercritical CO2 (SC-CO2) medium at temperatures of 75 and 105 degrees C and a constant CO2 density of 1.3 of its critical value. Before that, to determine the kinetic parameters of CO2 sorption by the polymer matrix, high-pressure NMR spectroscopy is used. By Raman spectroscopy, it is established that both polymethyl methacrylate samples contain carbamazepine, whose concentration in the polymer is 2.7 times higher for the case of impregnation at 105 degrees C compared to that at 75 degrees C. In addition, it is shown that, in the process of impregnation, CBZ is not crystallized in the polymer matrix, but rather forms a solution in PMMA, which, in turn, agrees well with the results of the X-ray phase analysis. The difference in the conformations of CBZ molecules in the polymer matrices impregnated at two different temperatures is established.