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Qiu W.,Chongqing University | Qiu W.,Guizhou Nanomaterials Engineering Center | Qiu W.,Guizhou Institute of Metallurgy and Chemical Engineering | Ma L.,Chongqing University | And 5 more authors.
Polymer Engineering and Science | Year: 2013

Polyaniline (PANI) nanofibers were prepared via the reaction of aniline with ammonium persulfate carried out in ethylene glycol (EG) medium without water. These purified PANI nanofibers could be dispersed in water and other polar solvents, such as ethanol, EG, and N,N-dimethylformamide, to form colloids. The morphology and structure of the PANI nanofibers were characterized and the effects of mechanical stirring on the morphology, structure, and electrical performance of PANI were investigated. The results indicated that the intermolecular H-bonding interaction between molecules of PANI and alcohol is advantageous to the one-dimensional growth of PANI, and a stirring reaction results in a lager size, a higher doping level, conductivity, degree of crystallinity, and oxidation than a nonstirring reaction. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers. Copyright © 2012 Society of Plastics Engineers. Source


Meng P.,Southwest University of Science and Technology | Xiong K.,Southwest University of Science and Technology | Ju K.,Guizhou Institute of Metallurgy and Chemical Engineering | Li S.,Southwest University of Science and Technology | Xu G.,Southwest University of Science and Technology
Journal of Magnetism and Magnetic Materials | Year: 2015

To achieve stronger microwave attenuation and larger bandwidth in electromagnetic absorber, the nickel ions (Ni2+) and manganese ions (Mn2+) were employed to partially replace the cobalt ions (Co2+) in BaCoTiFe10O19, and the doped barium hexaferrite (Ba(MnNi)0.2Co0.6TiFe10O19 and Ba(MnNi)0.25Co0.5TiFe10O19) powders were synthesized via the sol-gel combustion method. Subsequently, the microwave absorbing composites were prepared by mixing the ferrite powders with the paraffin. The X-ray diffraction (XRD) patterns of the doped ferrites confirmed the formation of the M-type barium ferrite, and no other types of barium ferrite could be found. Based on the electromagnetic parameters measured by the vector net-analyzer, it was found that the composite (Ba(MnNi)0.2Co0.6TiFe10O19) possessed a minimum reflection loss of -52.8 dB at 13.4 GHz with a matching thickness of 1.8 mm and the bandwidth below -15 dB was 5.8 GHz. Moreover, the maximum attenuation of Ba(MnNi)0.25Co0.5TiFe10O19 could reach -69 dB when its thickness was 1.8 mm, and also the bandwidth less than -20 dB was ranging from 13.2 GHz to 18 GHz. Thus, Ba(MnNi)0.2Co0.6TiFe10O19 and Ba(MnNi)0.25Co0.5TiFe10O19 could be the good microwave absorbers, which have great potentials to be applied in the high frequency fields of the microwave absorbing materials. © 2015 Published by Elsevier B.V. Source


Bai Y.,Chongqing University | Gan M.,Chongqing University | Qiu W.,Chongqing University | Qiu W.,Guizhou Nanomaterials Engineering Center | And 5 more authors.
Polymer Science - Series B | Year: 2014

The polyaniline-gold (PANI-AuNPs) fibrillar nanocomposites were prepared via a simple onepot synthesis route in ethylene glycol (EG) medium. The morphology of PANI-AuNPs was characterized by transmission electron microscopy (TEM), and their electrochemical properties were studied by CV, TAF and EIS measurement using an electrochemical workstation. The results show that the morphology of nanocomposites can be controlled by changing the temperature. The diameter of PANI-AuNPs composite nanofiber reduce from about 80 to 30 nm, and the size of AuNP also reduce from about 20 to 4 nm, with the rise of synthesized temperature. When the synthesized temperature is 10°C, the distribution of AuNPs is the best, and the amount of AuNPs dispersed in PANI is the most, as well as the electrochemical performance of PANI-AuNPs is the most excellent. © Pleiades Publishing, Ltd., 2014. Source


Qiu W.,Chongqing University | Qiu W.,Guizhou Nanomaterials Engineering Center | Qiu W.,Guizhou Institute of Metallurgy and Chemical Engineering | Ma L.,Chongqing University | And 6 more authors.
Journal of Nanoparticle Research | Year: 2014

The uniform polyaniline (PANI) nanorods were prepared by the chemical method with the assistance of ethylene glycol (EG) medium. The morphology and structure of the PANI nanorods were characterized by SEM, TEM, FTIR, and UV-vis technique, and the effects of stirring on the morphology, structure, electrical conductivity, and electrochemical behavior of PANI were investigated. The results showed that as-synthesized PANI can be facilely dispersed in water and ethanol to form colloids. During the reaction, the H-bonding between molecules of PANI and EG plays a key role for the one-dimensional. In the presence of stirring, uniform PANI nanorods with diameters of 50-80 nm and length up to 400-800 nm can be obtained, and the aspect ratio is about 4. While in the absence of stirring, the aspect ratio of nanorods increases to more than 10, the diameter and length are 20-60 nm and 0.2-1 lm, respectively. In addition, the stirring can result in a higher doping level, conductivity, and degree of oxidation. Based on these results, a possible formation mechanism of PANI nanostructures is presented. © Springer International Publishing Switzerland 2014. Source


Qiu W.,Guizhou Institute of Metallurgy and Chemical Engineering | Qiu W.,Guizhou Nnaomaterials Engineering Center | Qiu W.,Applied NanoMaterials | Huang H.,China Electric Power Research Institute | And 7 more authors.
Journal of Polymer Research | Year: 2011

Chloroaurate acid (HAuCl4) was used as an oxidant and aniline (ANI) was used as a reducing agent to prepare a polyaniline-gold (PANI-Au) composite film by in situ polymerization. The formation of the composite film was monitored using a quartz crystal microbalance (QCM). The effects of the concentrations of HAuCl4 and ANI as well as the reaction temperature on the formation of the PANI-Au composite film are discussed. The kinetics of the reaction were investigated by the QCM technique. The results indicate that the kinetics of the reaction are of order 0.5 with respect to HAuCl4 and 1.5 with respect to aniline. The film growth rate increased with increasing ANI, HAuCl4 concentration and reaction temperature. The activation energy calculated from the temperature dependence of the growth rate was 40.32±0.15 kJ/mol. In situ UV-visible spectra of the reaction process were obtained and compared to the reaction process using the QCM technique. © 2010 Springer Science+Business Media B.V. Source

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