Achieving reversible dispersion and facile modification of dried cellulose nanocrystals using polyethylene glycol dimethyl ether as a superior capping agent

The irreversible aggregation of nanocellulose during drying poses severe limitations to its practical applications. In this study, we developed a novel oven-drying system for cellulose nanocrystals (CNCs) using polyethylene glycol dimethyl ether (PD) as a capping agent. The incorporation of only 10 wt% PD (relative to dried CNC mass) into the CNC suspension effectively inhibited the formation of irreversible hydrogen bonds during drying, significantly enhancing both the redispersion rate and redispersion stability of dried CNCs. The redispersed CNC suspension fully restored the nanostructure and physicochemical properties identical to those of the original CNC suspension. The dried CNCs incorporated with PD (CNC PD ) not only retained its original crystal structure and crystallinity but also achieved higher thermal stability compared to original CNCs. Furthermore, CNC PD exhibited excellent redispersion in strongly polar aprotic solvents such as THF and DMSO, facilitating subsequent chemical modifications. In the modification process, PD can be regarded as a co-solvent without affecting the chemical modification of CNCs. After that, PD was conveniently removable through a simple water rinsing step. These results demonstrate PD's exceptional efficacy as a capping agent for preventing CNCs aggregation, thereby enabling convenient storage and application of CNCs in dried solid form.