Cotton fibers were modified by TEMPO oxidation, sodium periodate oxidation, and sodium chloroacetate etherification to obtain carboxylated cellulose fibers with similar carboxyl content (about 70 mmol/100 g). The characteristics of carboxylated cellulose fibers were analyzed by comparing the morphology, chemical structure, crystallinity, carboxyl content, yield, water retention value, degree of polymerization (DP), and cost. The results showed that etherification and oxidation are both important ways to introduce carboxyl groups into the molecular structure of cellulose. When the carboxyl group with similar content is introduced into cellulose, the three modification methods will encourage a certain degree of cellulose degradation. TEMPO oxidation and sodium periodate oxidation will degrade cellulose more obviously, whereas chloroacetate etherification can obtain a higher yield, DP, and lower cost.
