Synthesis and Characterization of Poly(ethylene glycol) Dimethacrylate Hydrogels

Facile synthesis and detailed characleri7.ation of photopolymerizable and biocompatible poly(ethylene glycol) dimetbacrylates (PEGDM) and their hydrogels are described. Combined analyses of H NMR and MALDI-TOF MS confirmed the formation of prepolymers of high purity and narrow mass distribution (PD < 1.02). A systematic investigation into the struCtW'e and mechanical properties of PEGDM hydrogels was performed to characterize the relationships between the network structure and gel properties. Small-angle neutron scattering was usccl to characterize the structural features of hydrogels with respect to their semidilute solution precursors. A welldefined structural length scale (correlation length) manifested as a maximum in the scattering intensity was observed for hydrogels derived from high molecular mass PEGDMs and/or high oligomer mass fractions. Hydrogels derived from lower molecular mass PEGDMs and/or low oligomer mass fractions exhibited multiple correlation lengths suggesting the formation of inhomogeneous gel structures. The shear moduli, determined from uniaxial compression measurement, showed that the gel structures correlate well with the gel mechanical properties.