CMC is easily dispersed in water at all temperatures, forming clear, colloidal solutions. The aqueous solubility varies with the degree of substitution (DS). The DS is defined as the average number of hydroxyl groups substituted per anhydroglucose unit and it is this that determines the aqueous solubility of the polymer. Thermal crosslinking reduces solubility while retaining water absorption, therefore producing materials suitable for water absorption.

I believe this is not the perfect answer you are seeking, but this would help you to understand the behavior of CMC with water. Hope it did help.

Disperse CMC in small amount of water by stirring it, then add the melt salt hhydride into the dispersed solution. and heating or you could use other solvent to aviod agglomeration. (I think you will find an answer more important to you, but you can benefit from what I wrote).

Hello dear Muhammad. CMC form aggregates in cool water, however you have to stir the solution for long time. Another hand, you can prepare your solution heating slightly your system, CMC will be completely soluble in water (2 or 7 wt%), despite that the system come back to room temperature Best regard.

Thank you for all the answers.

For Edwin A. Murillo, I did heating the solution while stirring the water-CMC solution (around 1% CMC i guess). But it separate into two different phases not long after the process was done. But when I use higher CMC concentration (around 5%) with exactly same technique, I can get homogeneous liquid. And I don't know why.

I make cmc solutions regularly with no problem. I mix them on a stir plate with a stir bar at 4*C for 4H to overnight, until it is in solution