How to prepare carboxymethyl chitosan into hydrogel (without adding other chemical reagents)

This problem seems to depend on the definition of hydrogel.

In fact, after carboxymethyl chitosan is dissolved in water, it will form a sol.

If the molecular weight is relatively small, the concentration is very dilute, which is basically in a solution state;

If the molecular weight is large, the concentration can be slightly larger, and the basically thick sol can also be called hydrogel.