Development of tailored polysaccharide gels through selective Diels–Alder crosslinking

Novel polysaccharide gels were prepared by a covalent crosslinking of xylan and cellulose derivatives through Diels–Alder (DA) cycloaddition. For this purpose, polysaccharide carbamates were synthesized through a modular approach that incorporated either furfuryl or maleimide moieties for DA reaction as well as solubilizing tertiary amino or quaternary ammonium moieties that facilitated water solubility. All compounds were fully characterized with respect to degrees of substitution (DS) and molecular structures. Organogels and hydrogels were prepared by selective covalent crosslinking of the derivatives through DA reaction. The gelation process was monitored by rheological measurements to evaluate the kinetics with respect to different crosslinking conditions and the gels were characterized with respect to mechanical properties as well as drying and reswelling behavior. Moreover, several side reactions that occurred during the gelation were identified and it was possible to adjust the molecular structure accordingly to avoid these issues. Thus, it was possible to obtain novel polysaccharide-based organogels and hydrogels that displayed thermoreversible behavior, as well as good mechanical stability and re-swelling capacities.