M.Sc Thesis

M.Sc StudentBialystocki Tslil
SubjectCarbonate-containing Porous Poly(urethane-urea)s from
DepartmentDepartment of Materials Science and Engineering
Supervisor PROF. Michael Silverstein
Full Thesis textFull thesis text - English Version


PolyHIPEs are highly porous polymers synthesized within high internal phase emulsions (HIPEs), emulsions with dispersed, internal phase contents of over 74 %. Almost all polyHIPEs are polymerized using conventional free radical polymerization (FRP) and almost all polyHIPEs are crosslinked to prevent collapse due to capillary forces during drying. Recent work has shown that biodegradable poly(urethane urea) (PUU) polyHIPEs based on polycaprolactone (PCL) oligomers and diisocyanates (DIs) can be synthesized using step-growth polymerization (SGP). The highly interconnected porous structures of such biocompatible, biodegradable polyHIPEs may prove advantageous for tissue engineering applications.

            The objectives of this research were: to synthesize crosslinked and non-crosslinked highly porous PUU polyHIPEs through the SPG of polyols; to evaluate the macromolecular structures, porous structures, and properties of the resulting materials; and to evaluate the potential of these materials as scaffolds for tissue engineering. Crosslinked polyHIPEs were synthesized using an oligomeric PCL triol and hexamethylene DI (HDI). Non-crosslinked polyHIPEs were synthesized using an oligomeric PCL diol or oligomeric polycarbonate (PC) diols and HDI. The macromolecular structures were characterized using Fourier transform infrared (FTIR) spectroscopy and the porous structures were characterized using scanning electron microscopy (SEM). The thermal properties were characterized using differential scanning calorimetry (DSC) and the mechanical properties were characterized using uniaxial compression tests. The potential for tissue engineering applications was evaluated by cell culture and cell growth.

The successfully synthesis of non-crosslinked PUU polyHIPEs was unprecedented and will enable the generation of novel families of non-crosslinked PUU polyHIPEs. The porous structures were, for the most part, similar to those of typical polyHIPEs. Most of the polyHIPEs had densities ranging from 0.13 to 0.21 g/cc. While the crosslinked polyHIPE was insoluble, the non-crosslinked polyHIPEs were, for the most part, soluble. The PUU properties were varied through polyol copolymerization. Unusually, one particular copolymer exhibited a relatively low modulus (0.07 MPa compared to around 0.18 MPa for the other polyHIPE copolymers). Interestingly, the cell growth on this particular copolymer was more successful than that on the other PCL-based and PC-based PUU polyHIPEs. This work demonstrated that the optimization of the chemical, physical, and mechanical properties of these polyHIPEs through a judicious choice of monomers can be used to facilitate the synthesis of novel scaffolds for tissue engineering applications.