Thioxanthone polyimide with high planar rigidity as well as preparation method and application thereof

The invention discloses thioxanthone polyimide with high planar rigidity and a preparation method of the thioxanthone polyimide. According to the preparation method, halogen atoms of dihalogenated thioxanthone are converted into cyano groups, then hydrolysis and acylating chlorination are carried out and then groups containing nitro groups are grafted through an amide reaction; then diamine monomers containing thioxanthone structures are obtained through reduction, and the thioxanthone polyimide with high planar rigidity is obtained through polymerization of the diamine monomers and dianhydride. According to the invention, a large-volume planar rigid thioxanthone structure is introduced into a polyimide main chain, so that a polyimide molecular chain can be piled up more tightly, the freevolume of a polymer is reduced, and the barrier property of polyimide is effectively improved. Meanwhile, the conjugated structure of the thioxanthone structure can improve the heat resistance and oxidation resistance stabili