▎ 摘　　要

NOVELTY - Preparation of graphene-carbon nanotube/waterborne polyurethane composite material comprises preparing graphene oxide aqueous dispersion; modifying with gamma -aminopropyltriethoxysilane; ultrasonically mixing with carbon nanotubes and freeze-drying to obtain graphene-carbon nanotube hybrid particles; reacting diisocyanate and oligomer diol in the presence of catalyst and chain extenders to obtain isocyanate (-NCO)-terminated linear polyurethane prepolymer; and adding graphene-carbon nanotube hybrid particles to -NCO-terminated linear polyurethane prepolymer, stirring, cooling, neutralizing, adding ethylenediamine, continuously stirring, and vacuum distilling. USE - Method for preparing graphene-carbon nanotube/waterborne polyurethane composite material used as environment-friendly waterborne paint. ADVANTAGE - The two components of prepared composite material have good compatibility. Modification with graphene-carbon nanotube hybrid particles improves thermal stability, mechanical properties and hydrophobicity of waterborne polyurethane. DETAILED DESCRIPTION - Preparation of graphene-carbon nanotube/waterborne polyurethane composite material comprises: (A) uniformly mixing graphite powder, concentrated sulfuric acid and sodium nitrate in ice water bath, slowly adding potassium permanganate, stirring and reacting in ice water bath for 0.5 hour, heating to 35 degrees C, stirring and reacting for 24 hours, placing in ice water bath, dropping distilled water to the reaction mixture, stirring for 0.5 hour, diluting with distilled water, dropping hydrogen peroxide and hydrochloric acid solution, standing for settling, centrifugally washing until pH is 5- 7, and ultrasonically stripping to obtain graphene oxide aqueous dispersion; (B) adjusting pH of graphene oxide aqueous dispersion to 8-12 with base, adding gamma -aminopropyltriethoxysilane, reacting at room temperature for 8-12 hours, washing with organic solvent, washing with distilled water until neutral, adding L-ascorbic acid, adjusting pH to 8-12 with base, heating to 70-90 degrees C and reacting for 2-6 hours, and washing with distilled water until neutral to obtain modified graphene oxide aqueous dispersion; (C) ultrasonically mixing carbon nanotubes and modified graphene oxide aqueous dispersion for 1-4 hours, and freeze-drying to obtain graphene-carbon nanotube hybrid particles; (D) reacting diisocyanate and oligomer diol in the presence of catalyst at 60-100 degrees C for 0.5-4 hours under inert atmosphere, adding first chain extender, reacting at 60-100 degrees C for 0.5-5 hours, adding second chain extender, reacting at 50-90 degrees C for 10 minutes to 4 hours, and adjusting viscosity with acetone to obtain isocyanate (-NCO)-terminated linear polyurethane prepolymer; and (E) adding graphene-carbon nanotube hybrid particles to -NCO-terminated linear polyurethane prepolymer, stirring at 50-70 degrees C for 1-2 hours, cooling to 30 -40 degrees C, adding neutralizer and neutralizing for 5-10 minutes, adding ethylenediamine, continuously stirring for 0.25-0.5 hour, and vacuum distilling to remove acetone.