2.2. Preparation of cellulose/CMC hydrogels
The 3 wt% cellulose solution was prepared as follows:
3 g CF-11 was dispersed into 97 g of 6 wt% NaOH/4 wt%
urea/90 wt% water mixture with stirring for 5 min and
then was stored under refrigeration (20 C) for 12 h.
The frozen solid was thawed and stirred extensively at
room temperature to obtain a transparent cellulose solution.
CMC was dissolved in the same solvent to obtain a
3 wt% polymer concentration. The CMC and cellulose solutions
were mixed with ratio of 5:5, 6:4, 7:3, 8:2 and 9:1 by
weight, respectively. ECH was added to the mixture as
cross-linker, stirred at 30 C for 2 h to obtain a homogeneous
solution, and then kept at 60 C for 12 h to prepare
gels. Gels were washed with water to obtain hydrogels.