▎ 摘　　要

NOVELTY - Producing silica hollow sphere/graphene oxide/polyimide composite film involves carrying out template method to obtain 'core-shell' structure of the microspheres and sintering at 650 degrees C for 3 hours to obtain nano-silica hollow spheres. The Hummers process is carried out to obtain graphene oxide nano-sheets. The 0.6g polyacrylic acid, water and 9 mL ammonia are mixed in 250mL three-necked flask at room temperature. The 180mL ethanol is added to 250mL three-necked flask. The mixture is stirred and 4.5mL tetraethyl orthosilicate is added to mixture to obtain white emulsion. USE - Method for producing silica hollow sphere/graphene oxide/polyimide composite film for printed circuit board (claimed). ADVANTAGE - The method enables to produce silica hollow sphere/graphene oxide/polyimide composite film that is high temperature resistant, flame retardant, and has high electric insulation, high frequency, low energy consumption, low dielectric constant, high speed transmission rate and good mechanical properties. DETAILED DESCRIPTION - Producing silica hollow sphere/graphene oxide/polyimide composite film involves carrying out template method to obtain 'core-shell' structure of the microspheres and sintering at 650 degrees C for 3 hours to obtain nano-silica hollow spheres. The Hummers process is carried out to obtain graphene oxide nano-sheets. The 0.6g polyacrylic acid, water and 9 mL ammonia are mixed in 250mL three-necked flask at room temperature. The 180mL ethanol is added to 250mL three-necked flask. The mixture is stirred and 4.5mL tetraethyl orthosilicate is added to mixture to obtain white emulsion. The emulsion is dried, ground and calcined at 650 degrees C to obtain white nano-silica hollow spheres. The 25mL concentrated sulfuric acid and concentrated nitric acid mixed solution is added to 75mL flask. The 2g expanded graphite and 12g potassium permanganate are slowly added to solution for 6-60 minutes. The solution is placed in ice water bath. The three-neck flask is placed in water bath at 35 degrees C and reaction is continued for 2 hours. The appropriate amount of deionized water is repeatedly added to mixture and the temperature of water bath is raised to 98 degrees C for 1 hour to obtain brown solution. The appropriate amount of 30% hydrogen peroxide solution is added to obtain bright yellow solution. The large amount of deionized water is added to mixture and reaction mixture is filtered to remove unreacted mixture of high potassium permanganate. The obtained liquid is centrifuged repeatedly until the pH of solution is 7. The obtained mixture is dried and pulverized to obtain graphite oxide powder. The obtained graphite oxide powder is added to deionized water and subjected to ultrasonic vibration for 3 hours. The mixture is dried to obtain graphene oxide nano-sheets. The desired composite material according to the performance requirements of inorganic content is selected. The required amount of graphene oxide nano-sheets and N,N-dimethylacetamide are added to the flask. The mixture is mechanically stirred and appropriate amount of 4,4'-diaminodiphenyl ether is added under nitrogen protected environment at 60 degrees C. The mixture is refluxed for 12 hours. The hollow nano silica spheres are added and mixture is ultrasonically stirred for 1 hour at 60 degrees C. The mixture is refluxed for 12 hours. The appropriate amount of pyromellitic dianhydride is added to the mixture and viscosity of mixture is sharply raised. The mixture is stirred to at room temperature for 24 hours to obtain nano-silica hollow spheres/graphene oxide/polyimide solution. The obtained nano-silica hollow spheres/graphene oxide/polyimide solution is coated on the glass film machine and then heated in oven. The thermal imidization process is carried out at 80 degrees C, 120 degrees C, 150 degrees C, 180 degrees C, 200 degrees C, 250 degrees C and 300 degrees C for 30 minutes each. The film is naturally cooled to obtain nano-silica hollow spheres/graphene oxide/polyimide composite film. The glass plate is placed in deionized water for stripping and dried in oven.