Ring opening in epoxidized SIS block copolymer with thiolated nucleophiles and their antioxidant activity

Abstract

The functionalization of poly(styrene-b-isoprene-b-styrene) block copolymer by full epoxidation of polyisoprene block and its subsequent epoxy rings opening with thiolated nucleophiles was studied. The optimal ring-opening conditions were microwave heating at 110 °C for 3 h in tetrahydrofuran as a solvent, using sodium benzylthiolate as a model system. Afterwards, this methodology was successfully extended to thiolated nucleophiles with aliphatic and heterocyclic substituents. The new derivatives were characterized by size exclusion chromatography, spectroscopic techniques (FTIR-ATR, 1H and 13C NMR), thermal methods (TGA and DSC), and scanning electron microscopy to study morphology. The antioxidant activity of new block copolymers was examined by 1,1-diphenyl-2-picrylhydrazyl test. The polymer films showed an efficient DPPH radical inhibition activity.