Enzymatic Synthesis of High-Molecular-Weight Poly(butylene succinate) and its Copolymers

A two-step synthesis of high-molecular-weight and bio-based poly(butylene succinate) (PBS) from succinic anhydride and butane-1,4-diol is established, in which the first step is a 12 h atmospheric polycondensation at 95 degrees C in the presence of succinic acid. The subsequent polymerization, catalyzed by Novozym 435 suspended in toluene, yields PBS with a molecular weight above 73 000 g mol(-1). The recovered lipase catalyst appears to give similar performance after six cycles. The versatility of this atmospheric synthetic route to PBS copolymers is validated through the syntheses of poly(butylene succinate-co-butylene malate) (PBSM), poly(butylene succinate-co-butylene fumarate) (PBSF), and poly(butylene succinate-co-butylene terephthalate) (PBST), in which succinic acid is replaced by corresponding di-acids as monomers.