κ-Carrageenan-grafting-copolymers by RAFT polymerization exhibiting CO2 adsorption properties

As sustainability requirements escalates in designing materials for CO 2 capture, approaches that utilize abundantly available biopolymers are becoming increasingly important. Carrageenan, a natural polysaccharide derived from red seaweed, is favored for its environmental advantages, unique functional properties, and plenty of hydroxyl groups that can be functionalized to enhance its overall performance. This study reports the first modification of κ-carrageenan (κC) as a novel macro-RAFT agent, achieved through a mixed anhydride formation approach. Successful functionalization of κC with tertiary amine-containing polymers through grafting was confirmed, and the controlled RAFT polymerization was validated through a kinetic study, with dispersity ( Ð ) values ranging from 1.7 to 2.9. The resulting κC-based graft copolymers modified κC’s initial solubility in organic solvent to become more soluble of up to 8 mg/mL, exhibited moderate thermal stability with degradation in the range of 250–450 °C, and altered its morphology compared to the pristine κC. The resulting κC-based graft copolymers demonstrated CO 2 capacity of up to 0.186 mmol g -1 at 1 bar and 273 K, indicating their potential to be developed as sustainable solid sorbents for CO 2 capture.