Rigidity of Two-Component Hydrogels Prepared from Alginate and Poly(ethylene glycol)−Diamines

Abstract

Alginate hydrogels have been attractive for a variety of biomedical applications, but they possess limited mechanical properties when ionically cross-linked with divalent cations. Therefore, covalent cross-linking of alginate with poly(ethylene glycol)−diamines of various molecular weights was investigated as a means to generate hydrogels with a range of mechanical properties. Hydrogels with a range of elastic moduli could be generated by controlling either the chain length of the cross-linking molecule or the cross-linking density. The elastic modulus increased gradually with an increase in cross-linking density or weight fraction of PEG in the hydrogel up to ∼27% (w/w) of PEG. The change of mechanical properties was interpreted in terms of molecular weight between cross-links (Mc) according to the rubber-elasticity model, and the results of this analysis were generally consistent with the measured PEG−diamine incorporation efficiencies in this range. However, as the weight fraction of PEG in the hydroge...