Synthesis and chain extension of poly( L -lactic acid- co -succinic acid- co -1,4-butene diol). L-Lactic acid (LA) was copolymerized with succinic acid(cas:110-15-6) (SA) and 1,4-butenediol (1,4-BED) in bulk state with titanium(IV) butoxide as a catalyst to produce poly(LA-co-SA-co-1,4-BED) (PLASBED).

Poly(L-lactic acid) (PLLA) homopolymer obtained from a direct condensation polymerization of LA had weight average molecular weight (Mw) less than 4.1 × 104 and was too brittle to prepare specimens for the tensile test. Addition of succinic acid(cas:110-15-6) and 1,4-BED to LA produced PLASB with Mw as high as 1.4 × 105 and exhibited tensile properties comparable to a commercially available high-molecular-weight PLLA.

Chain extension by intermolecular linking reaction through the unsaturated 1,4-BED units in PLASBED with benzoyl peroxide further increased the molecular weight and made PLASBED more ductile and flexible to show elongation at break as high as 450%.

Biodegradability of PLASBED measured by the modified Sturm test was nearly independent of the 1,4-BED content. Gel formation during the chain extension did not exert any significant influence on the biodegradability either. 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1116–1121, 2005