Synthesis and Characterization of Novel Biodegradable Poly(butylene succinate-co-triethylene glycol succinate) Copolymers

Novel biodegradable aliphatic polyesters, poly(butylene succinate-co-triethylene glycol succinate) (P(BS-co-TEGS)) and poly(butylene succinate) (PBS), were synthesized through a two-step procedure of esterification and polycondensation with succinic acid and 1,4-butanediol/triethylene glycol as raw materials as well as tetrabutyl titanate and diphenylphosphinic acid as the co-catalysts. The chemical structure and molecular weight of the copolymers were characterized by ¹H nuclear magnetic resonance (¹H NMR) and gel permeation chromatography (GPC), respectively. In addition, thermal properties, crystal structure and mechanical properties were also analyzed with various techniques. P(BS-co-TEGS) exhibited more excellent mechanical properties than PBS, especially in elongation at break. Meanwhile, the crystal structure and thermal stability of the P(BS-co-TEGS) have hardly changed. The crystallinity of P(BS-co-TEGS) was lower than that of PBS and decreased with the increase of mole ratio of triethylene glycol. With the increase of TEGS unit molar composition, the melting point (T_m), crystallization temperatures (T_c) and heat of fusion (ΔH_m) of P(BS-co-TEGS) decreased, while glass transition temperature (T_g) increased.