Biodegradable poly(lactic acid) polymers

The synthesis of poly(lactic acids) from the cyclic lactides and properties of the polymers prepared have been described. Degradation rates in vitro under homogeous and heterogeneous conditions have been measured. The kinetics of deesterification under homogeneous conditions is second order and an activation energy of 11 Kcal/mol has been calculated. This is comparable to the value found for the hydrolysis of alkyl acetates. A biological in vitro method for determining the degradation of poly(lactic acids) has been described. The method indicates, in accordance with expectations, that poly(dl-lactic acid) degrades at a faster rate than L(+) lactic acid. Initial results of medical evaluation of the polymers in suture, rod, and film form are presented.