Biodegradable All Polyester-Based Multiblock Copolymer Elastomers With Controlled Properties

We present here the synthesis of all polyester-based poly(butylene terephthalate)-block-poly(ethylene adipate) segmental multiblock copolymers (mBCPs), (PBT-b-PEA-b-PBT)(n), via a cascade polycondensation-coupling ring-opening polymerization (PROP) method using cyclic oligo(butylene terephthalate)s (COBTs) as monomers and polyethylene adipate (PEA) diol as the macroinitiator. The structure of copolyesters was characterized by H-1 quantitative NMR and H-1-H-1 gCOSY NMR spectroscopy, which reveals the randomly distributed copolyester segments in the main chains as the degree of randomness is equal to 1, arising from the transesterifications during PROP. Further investigations reveal that these segmental multiblock copolymers are elastomers with controlled properties, where the melting point, glass transition temperature (T-g), storage modulus, ratio of the loss modulus to the storage modulus (tan delta) and Young's modulus increase with the increment of the feeding content of COBTs, while the extensibility and biodegradable property decrease vice versa. The developed cascade polymerization method leads to the practical synthesis of environmentally-friendly biodegradable all polyester-based thermoplastic elastomers with tunable properties.