Graphene is a new material of monoatomic lamellar structure composed of carbon atoms. It has excellent light transmittance and thermal conductivity and is the thinnest, hardest and least resistive material known.Generally, graphite and alkali metal solids are used for continuous ball grinding in high-energy ball mills. Low-frequency and high-voltage pulse current is applied to the graphene dispersed in water to obtain water-soluble graphene containing only hydroxyl groups. Hydroxyl fossil inks show greater affinity to polar molecules such as water.
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 was added to a certain concentration of lye and dispersed into graphene oxide colloid solution by ultrasound. Excessive chloroacetic acid was added to convert the hydroxyl and epoxy groups on graphene oxide into carboxyl groups. Homogeneous carboxylated go solution was obtained. Carboxy-modified go plays an important role in the preparation of functionalized go. Various organic small molecules, macromolecules, biomacromolecules and functional materials containing reactive groups can be covalently bound to go by using the active carboxyl groups on the surface of go through amideation or esterification reaction.