Carboxymethylcellulose (CMC) is a water-soluble polymer, which is widely used in various
fields such as food additives, textiles, pharmaceuticals and cosmetics. In this study, hydrogel
was prepared from CMC by using calcium chloride as a crosslinking agent. Optimization
of the reaction was done through investigation of four different parameters which had
different percentage of CMC (w/v), percentage of calcium chloride (w/v), reaction time and
temperature. The gel content and swelling properties of the CMC hydrogel were studied.
The highest gel content was 85.33% at 7% of CMC (w/v) with 2% of calcium chloride (w/v)
in 24 hours reaction time at room temperature. The gel content increased with the increasing
concentration of CMC and CaCl2. This was due to the higher number of functional groups
of COO- that were available in more concentrated CMC which could crosslink with CaCl2
to give higher gel content. Increasing the percentage of CaCl2 will increase the electrostatic
attraction between anionic charges of polymer chains and multivalent cation (Ca2+) that
leads to increase in ionic crosslinking of CMC. The swelling properties of CMC hydrogel
showed that the optimum degree of swelling was 45.33 (g/g). The swelling capacity of the
hydrogel in water decreased with the increase of the gel content of CMC hydrogel. This
could be due to the increase in the degree of crosslinking of the CMC hydrogel.