Concomitant degradation in periodate oxidation of carboxymethyl cellulose

Conversion of carboxymethyl cellulose (CMC) to its dialdehyde derivatives by periodate oxidization in acid solutions has been investigated as a function of pH, temperature, reaction time and periodate dosage. Our results show that the stoichiometric ratio of NaIO4 to CMC and the pH of aqueous medium are substantially responsible for the aldehyde content and yield of the product. Laser light scattering (LLS) and wide angle X-ray diffraction (WAXD) measurements demonstrate that physical and chemical degradations concomitant with the oxidization process occur, leading to the decrease in 〈Rh〉 and crystallinity, respectively. The degradation mechanism for acid-catalyzed cleavage of β-1-4-glycosidic bond is proposed. Atomic force microscopy (AFM) images reveal the morphological changes of CMC with the degree of oxidization. The present study quantitatively indicates the substantial degradation in derivatization of cellulose by periodate oxidization method, and is helpful for exploring novel carboxymethyl polysaccharide derivatives.