Novel Biodegradable and Double Crystalline Multiblock Copolymers Comprising of Poly(butylene succinate) and Poly(ε-caprolactone): Synthesis, Characterization, and Properties

A series of double crystalline multiblock copolymers composed of poly­(butylene succinate) (PBS) and poly­(ε-caprolactone) (PCL) have been successfully synthesized with hexamethylene diisocyanate (HDI) as a chain extender. The copolymers were systematically characterized by ¹H NMR, GPC, TGA, DSC, WAXD, and mechanical testing. The results indicate that the PBS segment is immiscible with the PCL segment in the amorphous region. The copolymers follow a two-stage degradation behavior, and thermal stability increases with increasing PBS content. PBS and PCL in the copolymers crystallize and melt separately. The mechanical properties of the copolymers can be conveniently adjusted from rigid plastics to flexible elastomers by changing the feed composition. The impact strength is substantially improved by the incorporation of the PCL segment