High-Efficiency Carboxymethylation Achieved by Enhancing Hydroxyl Accessibility Through Glycerol Pretreatment of Bacterial Cellulose.

Due to its dense crystalline structure and extensive hydrogen bonding network, cellulose exhibits limited reactive accessibility and reactivity, which severely restricts the reaction efficiency, degree of substitution, and uniformity of cellulose modifications such as carboxymethylation. To overcome these limitations, this study developed a novel glycerol-based pretreatment strategy to disrupt the hydrogen bonding network of bacterial cellulose (BC), thereby improving its reactive accessibility. The results confirmed that glycerol pretreatment significantly enhanced the reactivity of BC. The reaction time for preparing carboxymethyl cellulose (CMC) from glycerol-pretreated powdered BC was reduced from 2 to 1 h, representing a 100% improvement in reaction efficiency. In addition, glycerol pretreatment facilitated the exposure of hydroxyl groups in BC, thereby increasing the degree of substitution of CMC from 0.297 to 0.433 and from 0.427 to a peak value of 0.626, an approximately 46% enhancement. In addition, the CMC films prepared from glycerol-pretreated BC exhibited significantly improved light transmittance, reaching over 95% in the wavelength range of 300-1000 nm. This study provides theoretical support and technical guidance for the efficient production of CMC, expands its application potential in high-end fields, and promotes the high-value utilization of cellulose resources.