Smart graphene dispersion stabilized by a CO2-removable polymer

Abstract

Polymeric dispersants play a pivotal role in improving graphene solubility in common solvents; however, the presence of such a foreign dispersant may exert a negative influence on the intrinsic properties of graphene. Thus, it is particularly important and challenging to remove the dispersant when graphene is used in end applications. Here, we report a smart graphene dispersion by a CO₂-triggered removable diblock polymer – poly(ethylene oxide)-b-poly(N-(3-((3-((4,6-bis((3-(dimethylamino)propyl)amino)-1,3,5-triazin-2-yl)amino)propyl)(methyl)amino)propyl)methacrylamide) (PEA). Using absorption spectroscopy, Raman spectroscopy, XPS spectroscopy and TGA measurements, it was found that PEA can not only strongly interact with graphene to form a stable, concentrated aqueous dispersion, but it can also be removed from the graphene surface upon CO₂ treatment as the tertiary amino groups along the polymer chain can be protonated, thus diminishing the affinity for graphene. This study may offer a general strategy for the design of removable dispersants for nanomaterials.