Emulsion-templated macroporous polycaprolactone: Synthesis, degradation, additive manufacturing, and cell-growth

PolyHIPEs are macroporous polymers templated within high internal phase emulsions (HIPEs). The ability to tailor the macromolecular and porous structures makes polyHIPEs of interest for three dimensional tissue engineering scaffolds. In this work, polyHIPEs with densities ranging from 0.18 to 0.28 g/cc were synthesized from novel biodegradable poly(ɛ-caprolactone) (PCL) macromers based on methacrylated oligomeric PCL diols of various molecular weights. Different types of internal phases generated porous structures that varied from networks of channels to highly interconnected voids. The crosslinked macromolecular structure limited PCL crystallization, resulting in elastomeric behavior with moduli of around 20 kPa. The HIPEs proved suitable for 3D printing both in air and in an innovative gel-bath. The suitability of the polyHIPEs for tissue engineering applications was indicated by their moduli, by their complete degradation within 4 h in 3 M NaOH, and by mesenchymal stem cells adhering and proliferating. The high level of viability can be attributed to the porosity that enables sufficient nutrient and waste diffusion. These results provide a foundation for designing 3D HIPE inks for printing macroporous tissue engineering scaffolds.