Controlling sol-gel polymerization by solvent selection to create tissue engineering scaffolds

Polyurethane xerogels with open pore networks were created via solution-gelation (sol-gel) polymerization. The solubility parameters of the solvent(s) and prepolymers and equilibrium swelling and extraction data were both used to select solvent(s) giving porous xerogels. Polycaprolactone (PCL) diol was combined with either poly(tetramethylene glycol) (PTMEG) or castor oil (CO), and the prepoplymer mixture gelled in an array of solvents through reaction with a triisocyanate. The behavior of the PCL/PTMEG system was mapped vs. all pure solvents used as well as several binary blends, and regions generating porous bodies were identified. Both this and the PCL/CO system were also prepared as dense materials, with equilibrium swelling and extractable fraction data generated in various solvents Analysis of this data also allowed for selection of appropriate solvents for porous xerogel formation. Porous xerogels were characterized via scanning electron microscopy and mercury intrusion porosimetry.