Porous polycaprolactone and polycarbonate poly(urethane urea)s via emulsion templating: structures, properties, cell growth‡

PolyHIPEs, macroporous polymers templated within high internal phase emulsions (HIPEs), emulsions with over 74% internal phase, are almost always crosslinked to prevent collapse during drying. Here, elastomeric poly(urethane urea) (PUU) polyHIPEs with highly interconnected open-cell structures were synthesized in water-in-oil (w/o) HIPEs. The urethane reactions between a diisocyanate and an oligomeric polyol (a poly(ε-caprolactone) (PCL) diol, a PCL triol, or an aliphatic polycarbonate (PC) diol) occurred in the external phase, while the water-diisocyanate urea reactions occurred at the oil–water interface. The resulting linear macromolecular structures produced unusually soluble polyHIPEs whose thermal transitions and mechanical properties could be fine-tuned through the polyol macromolecular structure and molecular weight and through the urea content (the hydroxyl to isocyanate ratio). The polyHIPEs underwent almost complete degradation in 3 M NaOH, with the PCL-based PUUs undergoing a significantly more rapid degradation. Cells growing in the polyHIPEs adhered to the walls, spread, and penetrated into the porous structures. This work demonstrates that elastomeric, degradable polyHIPEs with potential for tissue engineering applications can be synthesized through the emulsion templating of PUUs with linear macromolecular structures.