Synthesis and evaluation of novel injectable and biodegradable polyglycolide-based composites

Novel 3-arm methacrylate-endcapped biodegradable polyglycolide prepolymer was synthesized and characterized. Injectable and in situ curable composites formulated with the liquid prepolymer and bioabsorbable β-tricalcium phosphate were prepared. The pastelike composites were cured at room temperature using a redox-initiation system. The initial compressive strengths (CSs), curing time, exotherm, and degree of conversion of the cured composites were determined. The composites showed initial yield CS ranging from 20.1 to 92.3 MPa, modulus from 0.73 to 5.65 GPa, ultimate strength from 119.9 to 310.5 MPa, and toughness from 630 to 3930 N mm. Increasing filler content increased yield strength and modulus but decreased ultimate strength and toughness. Diametral tensile strength test showed the same trend as did CS test. Increasing filler content also increased curing time but decreased exotherm and degree of conversion. During the course of degradation, all the materials showed a significant burst degradation behavior within 24 h, followed by a significant increase in strength between Day 1 and Day 3, and then continuous degradation until no strength was detected. The composites with higher filler content retained their strengths longer but those with lower filler contents lost their strengths in 45 or 60 days. The degradation rate is filler-content dependent.