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 (M
c) 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 hydrogels increased
above 27%, regardless of the molecular weight of PEG, the elastic moduli decreased. This is not consistent
with prediction based on the rubber-elasticity theory, and this is likely due to the fact that this model
does not consider cross-linking with a second macromolecule. Importantly, the results of this study suggest
that the mechanical properties of hydrogels will be strongly affected by the properties of the cross-linking
molecule as the M
c of hydrogels falls below the molecular weight of the cross-linking molecule.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.