Hydroxylation and hydroxylation graphene belong to functional graphene.Generally, graphite and alkali metal solids are milled continuously in a high energy ball mill, and graphene dispersed in water is treated with low frequency and high voltage pulse current. Hydroxyl-only water-soluble graphene can be obtained. Hydroxyl graphene has a strong affinity for polar molecules such as water and other polar molecules in aqueous solution - OH is dominantly neutral, and has good biocompatibility.
Graphene is one of the materials with the highest known strength. At the same time, it has good toughness and can be bent. The theoretical young's modulus of graphene is up to 1.0tpa, and its inherent tensile strength is 130GPa. Reduced graphene modified by hydrogen plasma also has very good strength, with an average modulus of 0.25TPa. Graphene paper made of graphene sheets has many holes, making it brittle. However, when functionalized graphene is oxidized and made from functionalized graphene, graphene paper is exceptionally strong and tough.
Graphite oxide (GO) was added to a certain concentration of alkali solution and dispersed into graphene oxide colloidal solution by ultrasonic wave. The hydroxyl and epoxy groups on graphene oxide were converted into carboxyl groups by adding excessive chloroacetic acid. Homogeneous carboxylated graphene oxide solution was obtained. Carboxyl modified graphene oxide plays an important role in the preparation of functionalized graphene oxide. By amidation or esterification of active carboxyl groups on the surface of graphene oxide, various organic small molecules, polymers, biological macromolecules and functional materials containing active groups can be covalently bonded to graphene oxide.