Intrinsic phosphine oxide polyimide with high dielectric property and preparation method thereof

The invention belongs to the technical field of high polymer materials, and particularly relates to intrinsic phosphine oxide polyimide with high dielectric property and a preparation method of the intrinsic phosphine oxide polyimide. The preparation method comprises the following steps: firstly, reacting 4-bromobenzocyclobutene, n-butyllithium and phenyl phosphorus dichloride, and oxidizing with hydrogen peroxide to prepare phosphorus-oxygen benzocyclobutene; and then carrying out a Diels-Alder reaction with bismaleimide to prepare the intrinsic phosphine oxide polyimide with high dielectric property. The prepared phosphorus-oxygen benzocyclobutene is low in melting point, is soluble in most organic solvents, has excellent processability, can be fused and cured with bismaleimide in a mold, and can also be used for preparing a polyimide film by a tape casting method. Due to the existence of phosphorus-oxygen double bonds with high polarity, the polyimide prepared by the method has high thermal stability and h