Synthesis Of Micro/Nanostructures Of Functional Polyaniline And Its Derivatives By Self-assembly Method

In this article, micro/nanostructures of polyaniline(PANI) and its derivatives weresuccessfully prepared by self-assembly method. The formation mechanism and factors onstructure and properties of PANI were investigated. The morphology, size and fluorescenceproperty of the synthesized polyaniline were controlled by adjusting the multiple reactionconditions on purpose. In a redox reaction system, poly(o-chloroaniline) with differentmorphologies were successfully obtained through a self-assembly method and some of itsproperties were measured. Nanostructures of poly(dimethylaniline) were also investigatedby self-assembly method.The main results were as follows:1. Polyaniline micro/nanotubes with fluorescence propertiy were controllablyobtained in the presence of trifluoroacetic acid(TFA) and fluorescein sodium(FSS) as bothdopants in aqueous.The size,morphology, and fluorescence propertiy of the PANIstructures were controllably adjusted. The morphologies were affected by fluoresceinsodium concentration,acid concentration,acid and aniline molar ratio ([TFA]/[An]),reaction temperature,etc. In aqueous solution(0~5℃), w hen the0.25, polyaniline microtubes were both formed with an out diameter of about300nm, theinner diameter synthesized at [TFA]/[An]=0.5is about200nm, while the inner diameter is70nm as the [TFA]/[An] ratio is0.25. When the concentration of TFA increased from0.01M to4M, the prepared polyaniline transformed from micro/nanotube with a diameterof about300nm into nanorod a diameter of about200nm. The X-ray diffractionexperiments suggested that PANI was partly crystal.The conductivity of the synthesizedpolyaniline microtubes were10-2S/cm. The fluorescence properties of polyanilinemicrotubes were closely associated with the pH value. Infrared analysis and fluorescencespectra showed that fluorescein sodium structure had been introduced into the structure ofpolyaniline chain.2. In a redox initiation system of ascorbic acid(AA) and APS, shape-controllablepoly(o-chloroaniline)(POC) nanostructures including1D-nanorod,2D-nanoflakes, 3D-nanofiber networks and microspheres were obtained through a self-assembly process.It was found that the POC morphologies were strongly affected by the initial content ofascorbic acid used as as initiation system with APS and the molar ratio of ascorbic acid too-chloroaniline ([AA]/[OC]),and also affected by the the molar ratio of APS toOC([APS]/[OC]) and the temperature of reaction system.It was difficult to get1D-nanostructure for POC in normal acid(hydrochloric acid, sulfuric acid, phosphate,tartaric acid, citric acid, dodecyl benzene sulfonic acid) by self-assemly process. Theinitiation system of ascorbic acid and ammonium persulfate(AA-APS) was considered tobe probably playing an important role in forming the POC1D-nanostructures. X-raydiffraction experiments suggested that POC was mostly amorphous.3. The exploration of nanostructures of poly(dimethylaniline), such aspoly(2,3-dimethlaniline), poly(2,5-dimethylaniline), poly(2,6-dimethylaniline), was madehere by self-assembly method in trifluoroacetic acid and ascorbic acid. The experimentresults show that, as the larger space steric hindrance of dimethyl aniline, it was hard forpoly(dimethylaniline) to form uniform micro/nanostructures, the product was spherical, butit is less regular than poly(o-chloroaniline) microspheres. XRD analysis showed thatpoly(2,5-dimethylaniline) was part of crystalline material, the rest of thepoly(dimethylaniline) were amorphous materials.