Preparation of poly(butylene succinate) copolymers including L-aspartic acid

Copolymers of poly(butylene succinate) (PBS) with amino acids were produced from succinic acid (1), 1,4-butanediol (2) and 1 mol% of various amino acids. Their reaction time and molecular weight, as well as thermal and mechanical properties, were studied. The reaction time for polymerization was found to increase as the amount of amino acid was increased, except when L-aspartic acid (3) was used. The preparation of PBS copolymer including 3 was found to be quite different compared with the preparation of copolymer produced using amino acids. The thermal properties of copolymers including 3 are similar to those of the homopolymer without 3, yet the reaction time, molecular weight distribution and mechanical properties of the copolymers depend significantly on the amount of 3. The reaction time was found to decrease in proportion to the amount of 3. If 3 mol% of 3 is added to the polymerization process, the weight-average molecular weight was found to reach 247 000 in only 15 min. The molecular weight distribution (M-w/M-n) was found to increase and the break strain was found to decrease as the amount of 3 was increased. Similar effects due to the inclusion of 3 were observed in PBS copolymers including e-caprolactone (4) or 3-octadecyloxy-1,2-propanediol (5). Polymer Journal (2010) 42, 411-415; doi:10.1038/pj.2010.16; published online 24 March 2010