Design of remoldable, shape-memory, welded biomass composites based on the acetal bond of the cellulose chain

The growing environmental concern over petrochemical-based plastics continuously promotes the exploration of green and sustainable biomass-based covalent adaptable networks composites (CANs). Compared with petrochemical products, cellulose and its derivatives have overwhelming superiority in terms of availability, cost and biodegradability; nevertheless, CANs using the abundant acetal bonds in the cellulose chain rather than elaborately designing other types of dynamic covalent bonds still have not received sufficient attention. Herein, we report acetal-based cellulose covalent adaptable networks (ACC) synthesized with poly(ethylene glycol) diglycidyl ether as the crosslinker for hydroxypropyl cellulose and tetrabutylammonium bromide (TBAB) as an accelerant. For the first time, exchangeability of the cellulose chain acetal reversible bonds at elevated temperature have been demonstrated to endow ACC reprocessability, shape memory and welding. The TBAB has been used as an accelerant of dynamic exchange for acetal bonds first and its accelerating mechanism and advantages have also been investigated. In addition, the thermal, mechanical and hydrophilic properties of ACC can be adjusted by simply adjusting the raw material ratio and the ACC has excellent chemical and biodegradability. Hence, ACC will provide new ideas for solving white pollution and building new CANs.