Study On Polyaniline Synthesized By Microwave And Ionic Liquid Assisted & PAn/TiO₂ Composite

In the most of conductive polymer materials, polyaniline(PAn) will be one of conductive polymer, having the most application prospect, because of its environmental stability, structure diversity, high conductivity and low-production cost, etc. At present, polyaniline has already been utilized in many fields such as energy, photoelectron parts of an apparatus, sensor, molecular device as well as the electromagnetic screen, metal anticorrosion and the stealth technology.In this article, conductive polymer-polyaniline was synthesized by microwave method and microwave assisted ionic liquid method using aniline as the monomer, ammonium persulfate as initiator, sulfuric acid as doping agent. It had been considered four factors: microwave irradiating temperature, microwave irradiating time, microwave power and ionic liquid amount, which enormously influenced the performance of polyaniline in the polymerization process. Moreover, PAn/TiO2 composites, having different thickness of polyaniline, were synthesized in the suspending liquid of titanium dioxide (TiO2).The conductivity, chemical structure, thermostability, crystallinity of polyaniline were analyzed and characterized by modern testing, such as four-probe conductivity meter, FT-IR, XRD, TGA and UV, etc. It had been studied that the polyaniline thickness of PAn/TiO2 composite influenced its light degeneration performance. Light degeneration mechanism of PAn/TiO2 composite had been discussed. The results indicated that the conductivity of polyaniline reached 0.29S/cm, when the molar ratio of ammonium persulfate to aniline was 1:1, the microwave irradiating temperature was 60℃, the microwave irradiating time was 25min, and the microwave power was 800w.The conductivity of polyaniline was improved by adding the ionic liquid in the polymerization system; the conductivity may reach 0.61S/cm. The infrared spectrum analysis indicated that the doping of PAn was a protonation process in which the quinone imine nitrogen atom was preferential. The X-ray diffraction and the thermogravimetric analysis results indicated that polyaniline synthesized by microwave assisted ionic liquid, had higher crystallinity and thermostability. When the initial aniline volume was 0.3ml, an optimum of the synergetic effect was found for PAn/TiO2 composite to degrade methyl orange. Under visible light illumination, PAn/TiO2 composite absorbed photon, then generated electron-hole pairs. Electron-hole pairs could react with water to generate hydroxyl free radical and the ultra oxygen free radical, which degraded the methyl orange.