Research On Synthesis And Performance Of Silver-polyaniline Composite

Polyaniline (PANI) is of interest in materials science for its many characteristics;it can be prepared from a wide range of raw materials through simple syntheticmethods, and shows excellent electrical conductivity and electrical activity.Nano-silver materials are the subject of similar interest due to their high surfaceenergy and thermal conductivity performance, as well as excellent antimicrobial andbactericidal activity and catalytic property. Materials containing both nano-silver andPANI have received much attention during the last few years. It can display uniquecombinations of the complementary advantages of each material. It has potentialapplications because of higher conductivity, electrochemical response andelectrocatalytic performance.In this thesis, silver/polyaniline nanocomposite and CNTs/silver/polyanilineternary composite have been synthesized via double in-situ composite methods andin-situ reduction methods with additional reductant. Scanning electron microscopy(SEM), Transmission electron microscopy (TEM), Fourier transform infraredspectroscopy (FT-IR) and X-ray diffraction (XRD) were used to analyze surfacemorphology and structure. The conductive performance and thermal stability propertywere investigated by conductivity test and thermogravimetric analysis.The conclusions could be summarized as follows.Firstly, the ratio of ammonium persulfate to silver nitrate, the concentration ofnitric acid and aniline had a greater influence on morphology and conductivity ofsilver/polyaniline material. Uniform rod-shaped morphology was obtained when theratio of ammonium persulfate to silver nitrate was0.4. Much bigger concentration ofnitric acid can make the polyaniline chain further decompose and reduce theconductivity. Too high or low concentration of aniline also can reduce theconductivity.0.2mol/L aniline dissolved in1.0mol/L nitric acid was polymerized viamixed oxidation with the ratio of0.4, while the conductivity of silver/polyanilinepellet is up to10.2755S·cm-1.Secondly, Incorporation of acidified carbon nanotubes can improve theconductivity of silver/polyaniline because of carbon nanotubes forming a conductivechannel in the polymer matrix. The length and amount of carbon nanotubes may affect the conductivity of ternary composite. The conductivity of composite doped3%longcarbon nanotubes is best, which is up to58.8200S·cm-1。Thirdly, the electrical conductivity of hydrochloric acid-doped polyaniline isfound to be more than2or3orders of eigenstates polyaniline, as well as the electricalconductivity of silver/polyaniline is more2orders of hydrochloric acid-dopedpolyaniline. Morphology and conductivity of silver/polyaniline material is greatlyinfluenced by the concentration of hydrochloric acid, the amount of silver and theratio of Sodium borohydride to silver nitrate. The conductivity of the compositedepends on both the oxidation state of polyaniline and the silver content. Semi-redoxpolyaniline and increasing the silver content can improve the conductivity of thecomposite.