6 research outputs found
Glyceraldehyde as an efficient chemical crosslinker agent for the formation of chitosan hydrogels
The rheological changes that occur during the chemical gelation of semidilute solutions of chitosan in the presence of the lowâtoxicity agent glyceraldehyde (GCA) are presented and discussed in detail. The entanglement concentration for chitosan solutions was found to be approximately 0.2 wt.% and the rheological experiments were carried out on 1 wt.% chitosan solutions with various amounts of GCA at different temperatures (25 \ub0C and 40 \ub0C) and pH values (4.8 and 5.8). High crosslinker concentration, as well as elevated temperature and pH close to the pKa value (pH â 6.3â7) of chitosan are three parameters that all accelerate the gelation process. These conditions also promote a faster solidâlike response of the gelânetwork in the postâgel region after long curing times. The mesh size of the gelânetwork after a very long (18 h) curing time was found to contract with increasing level of crosslinker addition and elevated temperature. The gelation of chitosan in the presence of other chemical crosslinker agents (glutaraldehyde and genipin) is discussed and a comparison with GCA is made. Small angle neutron scattering (SANS) results reveal structural changes between chitosan solutions, incipient gels, and mature gels