In situ curable alpha-hydroxyacid based degradable polymer composites for injectable biomedical applications

In situ polymerizable liquid degradable oligomeric polyesters based upon alpha-hydroxyacids were synthesized and characterized. Injectable and in situ curable composites formulated with these oligomeric polyesters and bioabsorble beta-tricalcium phosphate, were prepared at room temperature using the redox-initiation system. The results show that increasing glycolic acid/l-lactic acid molar ratio increased the initial compressive and diametral tensile strengths and curing time but decreased the degree of conversion. Increasing molecular weight of oligomeric polyesters decreased the initial strengths, exotherm and conversion but increased the curing time. Increasing the number of initiator arm decreased the initial strengths and curing time but increased the exotherm and conversion. During the course of degradation, all the materials showed a burst degradation behavior within 24 h, followed by an increase in strength. The degradation rate is found to be dependant upon the molar ratio, molecular weight of oligomeric polyester, number of initiator arm and type of comonomer.