| Crosslinked hydrogels of poly(ethylene glycol) diacrylate (PEGDA) have been extensively used as scaffolds for applications in tissue engineering. In this thesis, PEGDA hydrogels were synthesized using visible light (514 nm in wavelength) in the presence of the visible light photosensitive dye, EosinY, the co-initiator, triethanolamine (TEA), a comonomer, N-vinyl pyrrolidone (NVP), a crosslinking agent, PEGDA, and an optional PEG monoacrylate monomer that contained the cell adhesive ligand RGD. Two major parts are included in this study, the first is investigation of this photo-initiation, and the second is development of a hydrogel synthesis model.;The initiation was investigated by coupling the experiments with an initiation model. The light absorption and the NVP polymerization under various conditions were measured. Based on the observations from experiments and previously reported data, a mechanism was proposed. This mechanism was able to describe the dynamics of light absorption in the polymerization. Also, the proposed mechanism was validated by NVP polymerization and implemented in a hydrogel synthesis model.;The hydrogel synthesis model was developed based on the kinetic approach using the Numerical Fractionation Technique. The model was used to predict the hydrogel properties such as gel fraction, crosslink density, and RGD incorporation under various polymerization conditions. The model and the experiments show that the synergistic cross-propagation between NVP and PEGDA results in an increase in rate of polymerization and leads to higher crosslink density. The model shows a reasonable agreement with the measured RGD concentration, except when measurements were deviated by swelling. The crosslink densities were compared with measured inverse swelling ratio. The model predictions were in agreement with the experimental measurements. In some cases, model predictability is affected by nonideality due to gelation such as the reduction in free volume and the reduction in available pendant double bonds.;Nevertheless, the hydrogel synthesis can be used as a guide for designing a hydrogel with the desired properties for the tissue engineering applications. |
