The utility of poly(ε-caprolactone) (PCL) as a shape memory polymer (SMP) may be improved by accelerating its degradation. Recently, we have reported novel semi-interpenetrating networks (semi-IPNs) composed of cross-linked PCL diacrylate (PCL-DA) and thermoplastic poly(L-lactic acid) (PLLA) that exhibited SMP behavior, accelerated degradation, and enhanced moduli versus the PCL-DA control. Herein, we systematically varied the thermoplastic component of the PCLbased semi-IPNs, incorporating homo-and copolymers based on lactic acid of different M n , hydrophilicity, and crystallinity. Specifically, semicrystalline PLLAs of different M n s (7.5, 15, 30, and 120 kDa) were explored as the thermoplastics in the semi-IPNs. Additionally, to probe crystallinity and hydrophilicity, amorphous (or nearly amorphous) thermoplastics of different hydrophilicities (PDLLA and PLGAs 85:15, 70:30, and 50:50, Llactide:glycolide mole % ratio) were employed. For all semi-IPNs, the wt % ratio of the cross-linked PCL-DA to thermoplastic was 75:25. The nature of the thermoplastics was linked to semi-IPN miscibility and the trends in accelerated degradation rates.

Substitution of 4-arm star macromers into PCL/PLLA semi-interpenetrating networks (semi-IPNs) afforded SMP bone scaffolds with enhanced self-fitting properties, and reduced solution viscosity allowed for broadened fabrication utility.