Synthesis and characterization of poly(butanediol sebacate-butanediol) terephthalate (PBSeT) reinforced by hydrogen bond containing amide group, with good mechanical properties and improved water vapor barrier

A PBSeT copolyester was synthesized by introducing a polar amide unit into the molecular chain, coordinating with decyldiamine through hydrogen bonds between the amide groups and hydrogen atoms on the chains. Two-step esterification and one-step polycondensation melt polymerization were adopted. ATR-FTIR and HNMR demonstrated the successful introduction of the amide unit. The effect of adding an amide unit on many properties was also discussed. Due to the formation of hydrogen bonds, both the force of molecular chain and the crystallinity increased by 5.91%. Consequently, yield and tear strength increased by 40.7% and 74.8%, respectively. The addition of 1,10-decyldiamine has no significant effect on the glass transition temperature and thermal stability of polyester. The introduction of an amide unit decreased free volume and increased combined crystallinity, which also increased the water vapor barrier. At the same time, PBSeT copolyester still maintained its biodegradability under hydrolysis and enzymatic hydrolysis. Addtionally, the change of surface morphology upon the degradation was examed by AFM. This work discussesed a synthesis method of PBSeT copolyester strengthened by the hydrogen bond. The modified material has higher crystallinity, better mechanical properties, and a better water vapor barrier while maintaining certain biodegradation ability. It can be used in disposable products, food packaging, and other fields.