Low‐molecular‐weight copolymers composed of L‐lactic acid and various DL‐hydroxy acids as biodegradable carriers

Abstract

AbstractBiodegradable copolymers of L‐lactic acid (L‐LA) and DL‐α‐hydroxy acids with relatively low molecular weights, for example L‐LA/DL‐lactic acid (DL‐LA), L‐LA/DL‐α‐hydroxybutyric acid (DL‐HBA), L‐LA/DL‐α‐hydroxyisovaleric acid (DL‐HIVA), and L‐LA/DL‐α‐hydroxyisocaproic acid (DL‐HICA), were synthesized by quantitative direct copolycondensation without catalysts at 200°C. The in vitro degradation, which was evaluated by measuring the weight loss of these copolymers in M/15 phosphate buffer solution (pH 7,2) without enzymes at 37°C, is strongly dependent on the kind and molecular weight of these copolymers, resulting in the formation of different degradation patterns such as parabola type (L‐LA/DL‐HBA system), linear type (L‐LA/DL‐LA system), and S type (L‐LA/DL‐HIVA and L‐LA/DL‐HICA systems).