Gelatin cryogel sheets (5%) were synthesized using...

Gelatin cryogel sheets (5%) were synthesized using glutaraldehyde as the cross-linker. The aldehyde groups of glutaraldehyde form covalent imine bonds with amino groups of gelatin. Initially different concentrations of gelatin were used (4%, 5%, 6% and 8% respectively). On physical examination of the cryogels produced with these concentrations, it was observed that at higher concentration of gelatin polymer (8%) the rate of polymerization was very fast and hence cryogel sheets formed were not proper. As the percentage of gelatin was increased the amount of cross-linker required was low i.e., the amount of cross-linker required decreases with increase in monomer concentration. Increase in polymer concentration also leads to less elasticity†¦show more content†¦Decrease in glutaraldehyde cross-linker on increasing the polymer precursor might be happening due to the increased probability of colliding polymers and cross linking agent in this unfrozen liquid microphase where all chemical reactions take place. More probability of colliding might be decreasing the amount of glutaraldehyde required to crosslink polymers for gel synthesis. It was also observed that if the amount of glutaraldehyde used was more than the optimum concentrations (Table 1.1), the gel formed lack porous network and were tough and brittle. When the glutaraldehyde concentration was reduced and kept lower than the optimized one, the gels were weak in mechanical strength. This observation suggests that there seems to be some competition between the nucleation process which takes place in frozen regions and gelation process which takes place in unfrozen liquid microphase. When the concentration of glutaraldehyde was lower than optimum, nucleation process dominates the gelation process and the gels formed were weak due to large pores and less polymer wall formation by cross linking of polymers. When glutaraldehyde quantity was taken more than optimum, gelation dominates the nucleation proc ess and the gels formed were without any pores and were brittle. Figure 1.1A shows the digital images of optimized gelatin sheets. Figure 1.1B and 1.1C shows that at an optimized polymer and cross-linker ratio