Novel Castor Oil-Derived Block Copolymers as Promising Candidates for Biological Applications: Biorelevant and Biocompatible

The castor oil-derived fatty acid (thioether-containing -hydroxyacid) is obtained using the UV-catalyzed thiol-Michael addition and is used for the first time as a monomer, for the development of biorelevant copolymers based on epsilon-caprolactone, methoxy-poly(ethylene glycol), and poly(ethylene glycol). Proton nuclear magnetic resonance, Fourier transform infrared spectroscopy, and size exclusion chromatography, confirm the successful synthesis of diblock and triblock copolymers with very narrow molecular weight distributions. X-ray diffractometry, polarizing light microscopy, and differential scanning calorimetry, suggest that crystallization of the crystalline block chains is restricted within the microphase-separated morphology and that it is strongly affected by the competition between the two semicrystalline blocks. Moreover, thermogravimetric analysis reveals that the thermal properties of the copolymers are intermediate between those of their parent homopolymers. Regardless of their block composition, the biorelevant copolyesters do not exhibit apparent cytotoxicity, according to the (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) (MTT) and fluorescence microscopy assays.