Fabrication of highly interconnected porous poly(ɛ-caprolactone) scaffolds with supercritical CO₂ foaming and polymer leaching

Highly interconnected porous poly(ɛ-caprolactone) (PCL) scaffolds combined with supercritical carbon dioxide (CO₂) foaming and a polymer leaching process were fabricated by blending PCL with water-soluble poly(ethyleneoxide) (PEO) as a sacrificial material. The effects of foaming conditions and the phase morphology of blend on foaming behavior and pore morphology were investigated. Rheological results and phase morphology indicated that the PCL and PEO were immiscible. For both spherical droplets and co-continuous phase morphologies of PCL/PEO blend, batch foaming experimental results indicated that increasing CO₂ saturation time and foaming pressure led to significant decreases in pore size, but increasing temperature led to opposite results. The incorporation of PEO not only facilitated the foaming of PCL by increasing its viscosity, but it also improved the porosity and interconnectivity of the post-leached PCL scaffolds. The porosity improved by up to 93.5%, and the open pore content increased by up to 90.9% for the PCL50 blend (50% PCL by weight). The leaching process had more contribution on the open pore content for PCL/PEO porous scaffolds with co-continuous phase morphologies than for the spherical droplet structures due to different cell-opening mechanisms. The results gathered in this study may provide a theoretical basis and data to support research into porous scaffolds for tissue engineering.