CO 2 /N 2 -triggered water-dispersible/collectable lignin- g -DEAEMA nanoparticles were successfully synthesized and were used to prepare emulsified/demulsified switchable Pickering emulsions by gas processing under nearly neutral conditions.
Water-insoluble lignin is modified via atom transfer radical polymerization (ATRP) grafting of 2-(diethylamino)ethyl methacrylate (DEAEMA). These lignin- g -DEAEMA samples can be easily dispersed in water upon CO 2 bubbling. They can also be quickly precipitated out by N 2 bubbling. The CO 2 /N 2 -switchability of dispersion/precipitation is correlated to the graft density and chain length of DEAEMA units. This gas-switchable feature gives the lignin materials a wide range of potential applications. Demonstrated in this work is the use of lignin- g -DEAEMA as a surfactant for Pickering emulsion. An emulsion of decane is prepared with the lignin nanoparticles and it can be demulsified and re-emulsified by bubbling of the two gases. The emulsification/demulsification processes are highly reversible and easily repeatable. This work represents an innovative approach in developing value-added lignin materials.