Study On Preparation Of Nano Polyaniline And Its Composite Particles

Conductive polyaniline as a new material of functional polymer is given moreandmore attention by scientists because of its simple synthesis methods, particulardopingmechanism, excellent environmental stability, as well as wide application.Nanomaterial has the special physical and chemical properties. Introducingnanotechnology into the synthetical technology of polyaniline, it has conductivity andnanoparticle function togethere. Because conductive aerosol particles require light qualityand good conductivity, we choose small desity fly-ash hollow cenosphere as core and goodconductive polyaniline as shell, polyaniline/fly-ash hollow cenosphere composite particlewith core-shell structure were prepared. The main content of research include three aspectsas follow:Preparation of polyaniline nanoparticles with microemulsion polymerization method:the influences of the type of emulsifier, polymerization time and the time ofpolymerization initiator dropping on the particle size and particle size distribution ofpolyaniline nanoparticles were discussed. The effects of the molar ratio of sodiumdodecylbenzene sulfonate to aniline, the molar ratio of ammonium persulphate to anilineand the system of the reaction temperature on conductivity and the particle size ofnanoparticles were also studied. The optimum technology conditions for the preparation ofpolyaniline nanoparticles in microemulsion were obtained: the molar ratio of emulsifiersodium dodecylbenzene sulfonate Acid to aniline was 1.5:1. The molar ratio of initiatorammonium persulphate to aniline was 1.25:1. The reaction temperature and the pH value ofthe system was respectively 10℃and 0.3. The time of polymerization initiator droppingwas controlled at 30 min. The polymerization time continued for 4 hours. Particle sizedistribution of polyaniline nanoparticles of this preparation techniques was best andnarrowest. Particle size was about 40nm. The electrical conductivity is around 10⁰ S/cm.Preparation of polyanline nanoparticles with dispersion polymerization method: theinfluences of the type of dispersant, the concentration of polyvinylpyrrolidone, theconcentration of ammonium persulphate, dispersion media on the particle size and particlesize distribution of polyanline nanoparticles were discussed. The effects of theconcentration of the Hydrochloric Acid on conductivity and the yield of polyanlinenanoparticles were also studied. The optimum technology conditions for the preparation ofpolyaniline nanoparticles with dispersion polymerization were attained: The concentrationof polyvinylpyrrolidone was 8g/L. The molar ratio of ammonium persulphate to anilinewas 2:1. The concentration of the Hydrochloric Acid was 1mol/L. The volume ratio of ethanol and water of the dispersion media was 5:5. Particle size of polyanline nanoparticlesof the preparation techniques was about 60nm and particles had good dispersity. Theelectrical conductivity is around 10^-1S/cm.Preparation of nano-polyaniline/hollow cenosphere composite particle with core-shellstructure by microemulsion polymerization: the influences of the kind of emulsifier,sodium dodecylbenzene sulfonate content, hollow cenosphere content on compositeparticle coated effect were studied. The optimum technology conditions for the preparationof the even and compact coated polyaniline / hollow cenosphere composite particle inmicroemulsion were attained: aniline 1g, sodium dodecylbenzene sulfonate 3.48g, hollowcenosphere 0.4g, ammonium persulphate 2.85g, under the protection of nitrogen,temperature 20℃, reaction 4h.