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 (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 SA 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.