Possibility of dopant morphology control in the process of polymer impregnation with pharmaceuticals in a supercritical CO2 medium

Abstract

In this paper we present the results of polymethylmethacrylate (PMMA) impregnation with carbamazepine (CBZ) in a supercritical carbon dioxide (scCO2) medium at two different temperatures (75 °C and 105 °C) at a constant CO2 density. The obtained impregnated PMMA samples were analyzed by PXRD and Raman spectroscopy techniques. We have found that, irrespective of the impregnation process temperature, CBZ entrapped in the polymer matrix does not crystallize there but a CBZ solution in the PMMA is formed instead. It has been found that the CBZ concentration in the PMMA matrix grows as the impregnation process temperature rises due to the increase in the CBZ equilibrium concentration in the scCO2 phase, at that the conformational state of the CBZ molecules in the PMMA matrix was also found to depend on the impregnation process temperature. Finally, we showed that depending on the impregnation process temperature it is possible to obtain a PMMA matrix with either an opened or a sealed porous structure. In the latter case, not only CBZ, but also CO2 can be entrapped, remaining in the PMMA matrix in the high-density fluid state.