▎ 摘　　要

NOVELTY - Preparing flame retardant polycarbonate using lanthanum stannate coated with graphene oxide comprises e.g. mixing aqueous solution of lanthanum nitrate having a molar concentration of 0.1 mol/l and aqueous solution of sodium stannate having a molar concentration of 0.1 mol/l in equal volume, stirring and then allowing to stand, ultrasonically dispersing oxidized graphene powder in water to obtain oxidized graphene dispersion, mixing solution with oxidized graphene dispersion, stirring, adjusting pH, stirring, allowing to stand, stirring and then washing with distilled water. USE - The method is useful for preparing flame retardant polycarbonate using lanthanum stannate coated with graphene oxide (claimed). ADVANTAGE - The polycarbonate has excellent mechanical properties, antistatic property and thermal stability. DETAILED DESCRIPTION - Preparing flame retardant polycarbonate using lanthanum stannate coated with graphene oxide comprises (i) mixing aqueous solution of lanthanum nitrate having a molar concentration of 0.1 mol/l and aqueous solution of sodium stannate having a molar concentration of 0.1 mol/l in equal volume, stirring and then allowing to stand, (ii) ultrasonically dispersing oxidized graphene powder in water to obtain oxidized graphene dispersion having a mass concentration of 0.8-1.4 mg/ml, (iii) mixing solution obtained in step (i) with oxidized graphene dispersion obtained in step (ii) in a mass ratio of 2-3:1, stirring, adjusting pH to 10-12 by adding saturated ammonia solution, stirring at room temperature for 3-5 hours, allowing to stand for 24-48 hours, under water bath at 80-90 degrees C, stirring to evaporate liquid, resulting solid was then washing with distilled water to neutral, washing resulting solid with distilled water to neutral, vacuum drying, grinding, sieving by 200-400 mesh sieve, raising temperature to 460-540 degrees C at a rate of 5-7 degrees C/minutes under nitrogen atmosphere, insulating for 1-2 hours, then raising temperature to 720-780 degrees C at a rate of 4-6 degrees C/minutes, insulating for 1.5-2.5 hours, under helium atmosphere at 340-390 degrees C at a rate of 3 -5 degrees C/minutes, insulating for 0.5-1 hours, then raising temperature to 800-850 degrees C at a rate of 2-4 degrees C, insulating for 2-3 hours, reducing temperature at 610-670 degrees C at a rate of 1-3 degrees C/minutes under carbon dioxide atmosphere, insulating for 1-2 hours, cooling to 240-280 degrees C at a rate of 2-4 degrees C/minutes, insulating for 0.5-1 hours, and then air-cooling to room temperature to obtain oxidized graphene coated lanthanum stannate, (iv) mixing mixture of bisphenol A, dimethyl carbonate at atmospheric pressure, adding 1-2 wt.% monobutyltin oxide equivalent to bisphenol A and 1-2 wt.% triphenylphosphine, heating in oil bath at 180-200 degrees C under nitrogen atmosphere, stirring reaction for 6-9 hours, distilling off unreacted dimethyl carbonate under reduced pressure at 130-150 degrees C to obtain to obtain pale yellow viscous bisphenol A dibutyl carbonate, and (v) mixing bisphenol A dibutyl carbonate and graphene-coated lanthanum stannate in a mass ratio of 3-4:1, ultrasonic dispersing for 1-2 hours, heating in oil bath at 180-200 degrees C, stirring reaction for 4-6 hours, distilling off unreacted dimethyl carbonate at 130-150 degrees C under reduced pressure, melt polymerizing to obtain crude polycarbonate, dissolving in methylene chloride, precipitating ethanol, filtering, and then vacuum drying to constant weight to obtain final product.