Study On Synthesis And Properties Of PANI Nanotubes By Self-assembly Method

Nanotubes have particular capability and purpose as nanomaterials of especialstructure, which is a new type nanomaterials in recent years. It is foreland andhotspot of the new international materials, and has obtained focus attention uponachievement. The synthesis of nanotubes gets a great deal of interest. Especially,Polymer nanotube s has become a new research hotspot as nanotube's importantembranchment. Scientists predicted that polymer nanotubes have attractedapplication foreground and potential value in the microelectronics,medicine fieldbecause of it's unique structure and excellent electrology,magnetic and opticscharacteristic.So far "template synthesis" method is a way of synthesizing nanotubes ofPANI at present time. However, these cases often require a rather tediouspostsynthesis process in order to remove the template, which make synthesis costhigh and produce rate low. Recently, Wan et al. invented termed as an in situ dopingpolymerization without template to synthesize polyaniline nanotubes, It has beendemonstrated that both acid as a dopant and in situ doping polymerization played animportant role in the forming process of nanotubes. Generally, nanostructures ofPANI was been synthesized by oxidant polymerization in the water with Ammoniumpersulfate(APS) as the oxidant and different acids as the dopant. Up to now, there aremany organic acids in order to synthesis nanotube,nanonod,flake of PANI, but nothree acids on our paper. This paper firstly introduced to synthesize nanotubes ofPANI with binary acid-Oxalic acid,surfactant-Ethylenediaminetet macetic acid,bioreagent -Amino acetic acid as the dopant and APS as the oxidant. The organicacid and aniline can form micelles that act as templates for synthesizingnanostructure of PANI by the self –assembly. The synthesizing nanotubes hasconductivity and been synthesized by equal ratio. The different nanotubes havedifferent conductivity because of different anion. On the bases of the results obtainedfrom IR,XRD and Uv-vis proved the structure of PANI and we find theconductivity of oxalic acid highest by comparing three acid. The morphology ofsynthesizing PANI by self-assembly method was changed, but molecule structureand mass state don't change, which is amorphous.Recently, conductive polymeric materials with attractive semiconductingproperties are finding growing applications in optoelectronic and microelectronicfields. Polyaniline(PANI) is unique among the known conducting polymer as itsconductivity is controlled by oxidation doping and proton doping. The authorsynthesized polyaniline nanotubes by self-assembly method and loaded Lithiumchloride from the viewpoint of applied science. The impedance of compositeproducts was studies at the different solvent and concentration of loading. The rangeof the variation of the impedance for composite products is extremely higher thanthat of bulk polyaniline. This kind of material has excellent sensitivity in humidityrange and overcame the defect of Lithium chloride when we used THF as the solvent.With the increase of the loading concentration, the humidity of material is better andbetter;when we used the water as solvent, the material overcame defect of bulk LiClin small range, but the humidity lag of the material is biggish.It is universally acknowledged that the polymeric process of Polyaniline isoxidative process of the monomer of aniline. Polyaniline was synthesized by themethod of anode oxidation and oxidant, it is electrochemical polymerization andchemical polymerization respectively. There are many oxidants in the polymerizationprocess of aniline, for example ammonium persulfate (NH4)2S2O8,H2O2,Fe3+,K2Cr2O7 and so on. The product of oxidative polymerization of aniline usingdichromate oxidant (K2Cr2O7) is soluble Cr3+ that would not remain in thepolyaniline product. This idea was sustained in lots of literatures. But in this paper,the product exist Cr(OH)3 intermediate when we used ammonium persulfate (APS)and potassium dichromate (K2Cr2O7) as the oxidant together andβ-Naphthalenesulfonic acid (β-NSA) as a dopant by self-assembly. The part ofCr(OH)3 react with β-NSA acid, the other were capped immediately by the aniliniumcations and be protected in the acid solution, in which caped Cr(OH)3 act as substrateand the micelle act as template formed the new morphology .The product was provedto be Polyaniline by the method of IR,XRD. The green powder was obtained bycalcined experiment and was analysed by XRD. The result indicates that the greenpowder is Cr2O3;The XRD peak of the product by carbonizing experiment reveal thepresence form of Cr compound;The EDX analysis indicated effectively that Crcompound existed in the resulting product. The potential reaction process wasdiscussed and guessed in this paper. The analysis indicated that two kinds ofreactions were taken place at the same time and Cr(OH)3–intermediate played a keyrole in the formation of cluster of nanorod .When the molar ratio of [An] / [K2Cr2O7]is 1, it is propitious to form cluster PANI morphology. There are a lot of clusternanonods, which possessed preferably orientation and conductivity. However, theexact growth mechanism of the cluster PANI nanorod is not very clear, the reactionmechanism need further study.