Novel Unsaturated Aliphatic Polyesters: Synthesis, Characterization, and Properties of Multiblock Copolymers Composing of Poly(Butylene Fumarate) and Poly(1,2-Propylene Succinate)

Widespread application of biodegradable polyesters is restrained by various disadvantages such as inadequate thermomechanical properties, high cost, and lack of reactive sites for further modification. Poly(butylene fumarate) (PBF), as a novel and low-cost aliphatic polyester, possesses good physical properties and reactive double bonds along with the polymer backbones which can be potentially modified to endow the polyester with specific properties. However, the biodegradation rate of PBF is too slow to meet the requirement of practical application. In this contribution, amorphous poly(1,2-propylene succinate) (PPS) was copolymerized with PBF to decrease the crystallinity (X-c) and accelerate the biodegradability of PBF via chain-extension with diisocyanate. The chemical structures of the copolymers were confirmed by H-1 NMR spectra and gel permeation chromatography (GPC). The crystal structure and physicochemical properties were investigated by wide-angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC), mechanical testing, and enzymatic degradation in detail. Both the impact strength and degradation rate of the copolymers are effectively improved by the introduction of amorphous PPS; while the melting point (T-m) and crystallization temperature (T-c) are hardly reduced by the incorporation of PPS. The novel polymer may be directed used as low-cost biodegradable materials or be further functionalized with special properties for particular applications.