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Research on the Preparation of Polyaniline Nanostructures by High Gravity Chemical Oxidative Polymerization

Author: LvXinWei
Tutor: WuWei
School: Beijing University of Chemical Technology
Course: Chemical Engineering and Technology
Keywords: Polyaniline High Gravity Polymerization Nanomaterials
CLC: TB383.1
Type: Master's thesis
Year: 2011
Downloads: 76
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Abstract

Polyaniline is a typical intrinsic type conductive polymer, it has the synthesis is simple, easily available cheap raw materials, the structural diversity, reversible doping / undoping performance, the reversible oxidation / reduction performance as well as good conductive properties, etc. advantage of by the people's attention. Nano polyaniline can be introduced to the special physical and chemical properties of nanomaterials have the size effect, surface effect and quantum effects conductive polyaniline, it sets conductivity nanomaterials functionality and integration, and thus has a very broad application prospects. Gravity technology is a new type of chemical process enhancement technology, can greatly strengthen the multiphase fluid between the mass transfer and micromixing. Rotating packed bed (RPB) is a common high gravity device, and has been successfully applied to a variety of nano-powder materials gravity technology. Gravity technology nanopowder materials have the advantages of short reaction time, small particle size of the product, and narrow particle size distribution, low cost, and amplification effect is small, easy to industrialization. On the basis of rapid mixing, the innovative gravity technology by chemical oxidation polymerization preparation of nano polyaniline successfully prepared nano-fiber morphology and nanoparticle morphology of polyaniline products and research The formation mechanism of nano polyaniline preparation process, influencing factors and application performance. The full text of the main research contents are as follows: 1. Were used rapid mixing and gravity method to the solution of chemical oxidative polymerization prepared polyaniline nanostructures, and proposed two different gravity technology nano polyaniline synthesis process: batch process and cyclic process. The study showed that: gravity environment has significant role in promoting the nucleation process of polyaniline, the nucleation induction of polyaniline in the reaction solution can be significantly shortened. The polyaniline prepared by the process of gravity method intermittently for nano-fibrous structure, having a diameter of 30-50nm; the gravity method circulating prepared resulting polyaniline nanoparticle structure. In the batch process, the process of the preparation of polyaniline of gravity method, the nano-polyaniline is the gradual growth from the start of grain structure of one-dimensional fibrous structure, the Super gravity environment to promote the reaction solution, a high degree of supersaturation formed in this process, conducive the formation of homogeneous nucleation environment conducive to the preparation of morphology the polyaniline nanofibers uniform structure. Gravity method can be implemented in a high monomer concentration (0.5mol / L) under the conditions of preparation of polyaniline nanofibers. Study the impact of various factors on the morphology and properties of nano polyaniline high gravity batch process, the preparation process of the polyaniline nanofibers. The study showed that: in a monomer concentration of 0.1 to 0.5 mol / L range, the diameter of the preparation of a batch process that can take advantage of gravity method in 30-50m, smooth surface of the polyaniline fibers. The average diameter of the polyaniline nanofibers with gravity rotating packed bed gravity level increases gradually reduced. The morphology of the polyaniline nanofibers prepared under the conditions of the higher reaction temperature was significantly superior to the product prepared under low temperature conditions. Prepared in the cold condition of polyaniline doping level is relatively high, the degree of crystallinity is also better. Perchloric acid, hydrochloric acid, sulfuric acid and phosphoric acid can be used as the gravity method preparation of a batch process the doping of the polyaniline nanofibers acid, wherein the perchloric acid and hydrochloric acid to the acid prepared in the morphology and properties of the polyaniline nanofibers is doped more excellent . Gravity prepared polyaniline nanofibers most suitable oxidizing dosage range for the molar ratio of the monomer with the oxidizing agent (An: APS) of between 4:1 and 2:1. 0-60 ℃ under conditions of gravity prepared polyaniline sample a weight-average molecular weight greater than 20,000, and polyaniline having a narrow molecular weight distribution prepared by the low temperature conditions. The reaction temperature for the conductive properties of the nanocrystalline 20 ℃ polyaniline. . Hypergravity prepared polyaniline nanofibers dispersion stability in different media, and to study the adsorption properties of polyaniline in the water system of hexavalent chromium ions. Study: the hypergravity prepared polyaniline nanofibers dispersion stability in the water system is better, poor dispersion stability in hydrochloric acid and anhydrous ethanol system. Polyaniline hexavalent chromium ions in aqueous solution has a strong adsorption capacity, adsorption equilibrium can be achieved within a short period of time (30min), but the equilibrium adsorption rate (about 99.7%).

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