Thermoresponsive polymers are a class of smart materials that exhibit change in their physical properties with temperature, which make them unique and useful materials in a wide range of biomedical applications. Soluplus®, a thermoresponsive block graft copolymer with poly(vinyl acetate) PVAc and poly(vinyl caprolactam) PVCL block grafted on a poly(ethelyne glycol) PEG backbone in a ratio of 30:57:13 respectively, is marketed by BASF Corporation, it aids in solubilizing and increasing the bioavailability of active Pharmaceutical ingredients in poorly water soluble drugs. In order to elucidate the effect of hydrophobic/hydrophilic balance on thermoresponsive behavior of Soluplus® in water. Soluplus® was hydrolyzed by methanolysis, which resulted in the quantitative conversion of PVAc to poly(vinyl alcohol) PVOH.NMR and IR spectroscopies were used to confirm the structure of the hydrolyzed sample. The cloud- point of the hydrolyzed sample was found to be lower than that of Soluplus®. Expectedly, the gelation temperature and concentration of the hydrolyzed was higher than that of Soluplus®, which was attributed to its hydrophilicity. The micelle size distribution was random and larger compared to those of the Soluplus® parent compound.
Abstract