Benzoxazine is a six-membered heterocyclic compound containing C, N, O made by condensation of phenol, primary amine and formaldehyde under Mannich condensation reaction under certain conditions. Its molecular structure contains a benzene ring, and a benzene ring is connected to the six-membered heterocyclic ring containing oxygen and nitrogen can undergo ring-opening polymerization under the action of heating or catalyst to form a network structure containing nitrogen and similar to phenolic resin. Its cured product has low dielectric constant and dielectric loss, low water absorption rate, high heat resistance, processing dimensional stability, and good flame-retardant characteristics, so that its application in the field of electronic products has attracted much attention.
Benzoxazine has good physical and mechanical properties, and it is widely used in engineering materials such as refractory materials, coating materials, friction materials and adhesives. As researchers continue to conduct in-depth research on it, it is found that benzoxazine has the characteristics of flexible structure design, many active functional groups, controllable distribution and strong acid resistance. It has the conditions to develop into a functional material, and in terms of adsorption there is great potential.
Fig 2. Synthesis of benzoxazine
With the rise and development of new material industry, benzoxazine resin has attracted more and more attention of scientists, and provides a better choice for polymer materials in microelectronics, aerospace and other industries. Benzoxazine resin can be synthesized by solution method, suspension method and solvent-free method. Researchers focus on the modification methods of p-benzoxazine resin: modification design of main chain and side chain of p-benzoxazine resin; blending with other high-performance resin or fiber, and blending with inorganic materials. The new structure benzoxazine functional resin has been enhanced in heat resistance and flame retardancy, dielectric and thermal conductivity, curing and adsorption properties. Benzoxazine Resin can be used in water treatment to remove oil and organic solvents, organic dyes, and heavy metal ions. Benzoxazine Resin can also be used to adsorb carbon dioxide as drug carrier.
In the aspect of electricity storage, benzoxazine based porous carbon materials are often used in the electrode materials of supercapacitors and batteries in combination with other materials. As a new type of energy storage device, super capacitor has the characteristics of high power density, short charging time, long service life, good temperature characteristics, energy saving and environmental protection, and is applied to portable electronic equipment, electric vehicles and energy regeneration systems. Porous carbon material is always the ideal electrode material for supercapacitor because of its high specific surface area, good chemical stability, low cost and variety of forms. In addition to the advantages of the above-mentioned carbon materials, the porous carbon materials based on benzoxazine can produce enough electron supply and electron absorption effects by selecting appropriate raw materials because of the existence of nitrogen and oxygen heteroatoms on the carbon skeleton and the introduction of more active groups of other heteroatoms through molecular design properties, wettability, number, type and distribution of surface functional groups can also be flexibly controlled by molecular design, which makes benzoxazine carbon material suitable for making electrode materials of supercapacitor.