Construction of Degradable Biobased Thermoplastic Polyester Elastomer with 2,5-Furandicarboxylic Acid and Lactic Acid

The use of renewable biomass resources as alternatives to petroleum-based feedstocks represents an important strategy for mitigating the shortage of petrochemical resources. Substituting terephthalic acid with 2,5-furandicarboxylic acid (FDCA) has become a widely adopted approach. This study introduces a method of incorporating renewable lactic acid in place of petroleum-derived soft segments to produce elastomers through copolymerization with FDCA-based polyester PBF. Ethyl lactate was converted into the SLA monomer with terminal functional groups via alcoholysis with a cyclic anhydride and then used to synthesize PBLF copolyesters with a number-average molecular weight (Mn) exceeding 32 000 g/mol through direct polycondensation. The resulting PBLF copolyesters exhibited tunable elasticity by varying the SLA content. Moreover, these copolyesters demonstrate high thermal stability and are capable of complete enzymatic degradation within 28 days. To enhance the modulus of the elastomers, micro-cross-linking was implemented, which significantly improved both modulus and strength. Furthermore, room-temperature annealing was performed to examine the effect of annealing duration on thermomechanical properties and microphase separation.