Ionically Crosslinked Thermoresponsive Chitosan Hydrogels formed In Situ: A Conceptual Basis for Deeper Understanding

In situ formation and the performance of ionically crosslinked thermosensitive chitosan‐based hydrogels are presented. Experimental analyses, together with mechanistic descriptions of the events during hydrolysis, are employed to uncover the role of urea and isobutanol as chemical modifiers by comparing three classes of hydrogels formed in chitosan/β‐glycerolphosphate (β‐GP) solutions. Rheological measurements demonstrate that urea caused an increase in gelation time and temperature of chitosan/β‐GP systems, while isobutanol has an inverse effect. Interpretations based on increase in pH and chemical bonding of components in chitosan solutions provide further insight into hydrogel network formation. Urea can hinder the hydrophobic characteristics of chitosan‐based hydrogels, whereas isobutanol has the opposite effect. The shape retaining strategy applied here helps in simulation and interpretation of performance of thermosensitive hydrogels for biomedical purposes.