Ionic, Covalent, and Covalent-Ionic Chitosan Hydrogels with 5-Norbornene-2,3-Dicarboxylic Crosslinker

Ionic, covalent, covalent-ionic hydrogels of chitosan and 5-norbornene-dicarboxylic acid or its anhydride as crosslinker were obtained. The developed synthetic routes of ionic and covalent crosslinking of chitosan make it possible to have a significant effect on the molecular structure of polymer networks of hydrogels, their rheological properties, and ability to swell at various pH. The concentration of the crosslinker is an additional factor in the directional regulation of the listed properties of hydrogels in intervals, the boundaries of which are set by the nature of chemical bonds in crosslinkers. The results obtained make it possible to predict and select the optimal samples for the development and improvement of hydrogel materials based on chitosan for biomedical applications.