Mechanisms of polymer degradation in implantable devices. I. Poly(caprolactone)

Poly(caprolactone) is a biodegradable aliphatic (poly(alpha-hydroxy acid), with important applications in the field of human therapy, due to its biocompatibility and bioresorbability. The degradation of poly(alpha-hydroxy acids) depends on chemical hydrolysis, but there is much interest in the precise mechanisms, including the role of free radicals, especially oxygen free radicals and their role in human disease. The hydrolytic degradation of poly(caprolactone) in aqueous environments was used as the control in a study of the effects of hydroxyl radicals in aqueous solutions. Different methods (GPC, DSC, SEM) were employed to investigate the mechanism of degradation of this semicrystalline physiologically absorbable polymer. The data indicate that hydroxyl radical is likely to be a major factor in the degradation of this polymer.