Study On The Synthesis, Characterization And Properties Of Polyaniline Doped With Sulfonic Acid

Chromogenic material is a new type of functional material, to which people have paid close attention recently. It includes thermochromic materials, photochromic materials, electrochromic materials, and so on. Usually, conductive polymers have electrochromic properties. Among them, polyaniline has wide foreground of exploitation and application in the field of smart windows,second batteries and so on because of its diversified structure(namely rich colors), excellent environmental stability, relatively high conductivity, low cost, simple polymerization process, and especially dissolvability and processability improved remarkably by special doped-method. As main methods syntheisizing polyaniline at present, many chemical methods have existed lots of questions, such as pollution to environment brought by organic solvents and high cost. Therefore this article puts forward synthesis of functional emulsion of polyaniline, which can be brushed into films directly, and preparation of polyaniline in two-phase emulsion system. In the systems which contain different additives, polyaniline/poly(vinyl alcohol), polyaniline/poly(glycol-octyl-phenyl aether), and polyaniline are synthesized. Furthermore, by comparing their processes of emulsion polymerization, qualities of films brushed with the emulsions, and electronic properties films, the author finally fixes on the system poly(vinyl alcohol) existing as the emphasis of research. In this system, dodecylbenzene sulfonic acid-doped polyaniline/poly(vinyl alcohol) emulsion, with which films gained have electrochromic properties, is prepared using situ-doped emulsion polymerization, and is easy to manufacture into films. The electrochromic properties of films after simple purification is promoted greatly(behaving widened-extension and shortened-electrochromic time). Have studied the effects of the amount of poly(vinyl alcohol), dodecylbenzene sulfonic acid and oxidant, reaction temperature, reaction time, mill speed, and dropping speed of oxidant on electrochemical properties(electrochromic properties and conductivity) of polyaniline/poly(vinyl alcohol) films and on the yield of polyaniline. The result of orthogoral experiments indicates that the best reaction craft for shortly electrochromic time of films is:5.3 percent for the quality content of poly(vinyl alcohol), 1.5 for the ratio between dopant and aniline, 1 for the ratio between oxidant and aniline, and 8℃for reaction temperature. Also, there isn't consistent between fast electrochromic time and relatively high conductivity. Moreover, electrochromic properties of films by the experimental method in this article are better than by situ-adsorption and mixed-inunction. Utilizing heat aging experiments, thermal analysis technique, X-ray diffraction etc, this article investigates stability and crystal properties of polyaniline/poly(vinyl alcohol) films. The effect of the amount of poly(vinyl alcohol) on electrochromic properties is observed and discussed by scanning electronic microscope. Based on phenomena of experiments, analyzes and discusses emulsion polymerization mechanism of sulfonic acid doped-ployaniline/poly(vinyl alcohol) and electrochromic mechanism of films, which bears some guidance in theory and practice for the preparation of polyaniline by situ-doped emulsion polymerization.