scCO2-assisted Impregnation of Polymers: Specific Phenomena Involved in the Impregnation of Two Compounds
In order to reduce the side effects of oral or injection drug administrations, the supercritical CO2 (scCO2) assisted impregnation has been used to develop new systems of local drug delivery. Even though this process is well known regarding the influence of the operational conditions and the influence of the physical-chemical interactions on the impregnation of one compound into a polymeric matrix, there is no systematic study about these parameters for multicompounds systems, such as natural extracts, and yet their impregnation has gained attention. The present study aimed to identify and explain the specific phenomena of the simultaneous impregnation of different compounds into a polymer in order to optimize the impregnation process of multicompounds systems. We have chosen a model of one polymeric matrix, Poly(L-Lactic Acid) (PLLA) or Linear Low-Density Polyethylene (LLDPE) , and the combination of two compounds among aspirin, ketoprofen and carvone. The impregnation was investigated in two conditions, {60 ºC; 90 bar} and {80 ºC; 300 bar}, for three hours. The impregnation yields were measured gravimetrically and by HPLC, FTIR analyses permitted to evaluate the interaction between matrix and compound, and DSC allowed evidencing the impact of the impregnation process on the PLLA microstructure. PLLA presented higher amounts of impregnation than LLDPE, however they both presented the same tendency. At {60ºC; 90bar}, carvone showed a good impregnation, thus helping aspirin and ketoprofen impregnation due its plasticizing effect. At {80ºC; 300bar}, ketoprofen and aspirin showed higher impregnations, thus helping carvone impregnation. The results indicate that the presence of a high plasticizing action compound in a given temperature and pressure condition helps in the impregnation of the other compounds. The release profiles of simultaneously and individually impregnated compounds in PLLA were compared.