Poly(Butylene Succinate) Copolyesters Modified with Linear-Chain Diols toward Adjustable Thermal, Mechanical, and Biodegradable Properties

The production and application of poly(butylene succinate) (PBS) still face challenges such as high production costs, insufficient toughness, and slow biodegradation. This study utilizes the ring-opening condensation polymerization method to prepare PBS copolyesters using succinic anhydride (SAA) and 1,4-butanediol (BDO) as raw materials, with 20 moL% different lengths of linear-chain diols as third monomers (carbon numbers are 3, 5, 6, 8, 9,10, and 12). Both PBS and its copolyesters exhibit high weight average molecular weights (18.8 × 10⁴–26.1 × 10⁴ g moL⁻¹), much higher than those obtained through the traditional conventional direct esterification method. Incorporating the third monomer reduces the glass transition temperature (T_g), crystallinity, and melting point (T_m) of the copolyesters. As the chain length of the third monomer increases, the copolyesters show improved toughness, with the elongation at break and notch impact strength of poly(butylene succinate-ran-dodecylene succinate) (P(BS-ran-DoS)) increasing from 374.1% and 5.6 KJ m⁻² of PBS to 723.2% and 64.8 KJ m⁻², respectively. The degradation rate of the copolyesters modified with short-chain diols increases significantly, and as the chain length of the third monomer increases, the degradation rate of the copolyesters slows down. Therefore, the selection of the third monomer can be used to adjust the properties of the polymer.