Synthesis of poly(butylene succinate) and poly(ethylene succinate) including diglycollate moiety

Poly(butylene succinate) (PBS) copolymers were prepared from succinic acid, diglycollic acid, and 1,4-butanediol, in the presence of titanium tetraisopropoxide and magnesium hydrogen phosphate trihydrate. All the polymers produced exhibited a higher number-average molecular weight than 65,000. The composition of the copolymers was found to be almost the same as the feed composition. The copolymers exhibited a higher break strain compared to the homopolymer. The biodegradability of copolymers showed a maximum when 2% diglycollic acid was added. However, the addition of more diglycollic acid decreased biodegradability. Poly(ethylene succinate) (PES) copolymers, including diglycollate moiety, were also prepared from succinic acid, diglycollic acid, and ethylene glycol, using the same reaction conditions as the PBS copolymers. Unlike the PBS copolymers, the molecular weights of the PES copolymers decreased for an increasing amount of diglycollate while the biodegradability rose with an increase of the diglycollate ratio in the copolymers, in the range 0-20%.