Gas‐Induced Reversible Dispersion/Aggregation of Graphene

Abstract The low dispersibility of graphene in water, given its hydrophobic nature, is considered a serious problem that limits its use. Here, we describe a method to stably disperse graphene using a dispersant containing a tertiary amine and a pyrene group. The dispersant modifies the graphene surface via π–π stacking, allowing it to be dispersed in water. The dispersant undergoes a hydrophobic–hydrophilic transition upon being stimulated by CO₂ and N₂, exhibiting a faster response (reaction time of 1.5 min) and lower recovery temperature (40 °C) than those of compounds with amidine‐like structures. We found that the graphene modified by this gas‐sensitive dispersant exhibited reversible dispersion/aggregation behavior upon the bubbling/removal of CO₂. The proposed method is a simple one for the reversible dispersion/aggregation of graphene by stimulating it with a gas and should be suitable for fabricating sensors, drug‐delivery systems, “smart” surfaces, and switching devices.