Synthesis and in vitro degradations of low‐molecular‐weight copolyesters composed of L ‐lactic acid and aromatic hydroxy acids

L‐lactic acid (LA) was copolycondensed with various aromatic hydroxy acids such as p‐hydroxybenzoic acid (HBA), p‐hydroxyphenylacetic acid (HPAA), and p‐3‐(hydroxyphenyl)propionic acid (HPPA) in the absence of catalysts, in order to investigate the copolymerizability and in vitro degradation. The results of 1H NMR spectroscopy and gel permeation chromatography (GPC) showed that the reaction proceeds quantitatively, but the molecular weight of the copolyesters is relatively low. The in vitro degradation pattern of copoly(LA/HPPA) was changed into an S‐type from a parabolic‐type with increasing HPPA content in the copolyester, in contrast to only parabolic‐type for both copoly(LA/HBA) and copoly(LA/HPAA).