Reaction kinetics and gel properties of blocked diisocyinate crosslinked chitosan hydrogels

Cure kinetics and network properties of hydrogels prepared by the reaction of chitosan and a water-soluble blocked diisocyanate cross-linker have been measured using swelling experiments and rheometry. The gel time measured by two different rheological methods, the rate equivalence of the change in modulus as a function of reaction time (G′G″ crossover) and the critical gel via the Winter–Chambon approach, are comparable. The reaction rate increased with increased temperature following the Arrhenius behavior, from which apparent activation energies can be determined. The network moduli can be tailored by adjusting the ratio of chitosan to cross-linker or the solution concentration. This allows for the formation of processable chemically cross-linked chitosan hydrogels with controlled kinetics and mechanical properties.