Cellulose-Based Irreversible Hydrogels Used for CO2 Sequestration

CO2-switchable hydrogels have been well documented during the past decade; however, the reversible response makes them unable to sequestrate CO2 owing to the gas release and viscosity reduction under high temperatures, weakening their capacity to absorb CO2. To address this issue, a series of copolymers based on grafting poly(dimethylaminopropyl methacrylamide) onto the backbone of sodium carboxymethyl cellulose (NaCMC) were prepared, characterized, and examined rheologically. In the semidilute entangled regime, the copolymer aqueous solutions can be gelled in the presence of CO2, but they cannot revert to the solution phase after bubbling N2 at 60 °C. With such irreversibility, 1 wt % aqueous solution of the copolymer with 24.88 mol % DMAPMAm can absorb CO2 up to 12.1 mg·g–1, whereas only 18.2% of the absorbed CO2 is released after heating at 60 °C. This work paves a new way to develop irreversible hydrogels for CO2 sequestration.