Formation of bio-based elastomer from styrene-butadiene copolymer and epoxidized soybean oil

Styrene-butadiene copolymers and epoxidized soybean oil (ESO) were used to synthesize bio-elastomers. The reaction occurred via a living anionic polymerization using n-butyllithium as initiator and cyclohexane as solvent. The gel permeation chromatography (GPC), ¹HNMR and FTIR spectroscopy analysis of the microstructure of precursor styrene-butadiene copolymers and the final products suggests that the ester group in the triglyceride of ESO was broken and reacted with the living polymer chain to form the bio-elastomer. The effect of the molecular weight of styrene-butadiene copolymer and the molar ratio of precursor copolymer to ESO on the formation of bio-elastomer are studied. The bio-elastomer based on styrene-butadiene diblock copolymer (SB) reveal higher tensile strength and break elongation compared with the precursor copolymer, but the one based on styrene-butadiene triblock copolymer (SBS) shown the opposite result.