Mengyu Gan

Preparation and microwave absorbing properties of polyaniline-modified silicon carbide composites

Polyaniline (PANI)/silicon carbide (SiC) composites were prepared by emulsion polymerization using sodium dodecylbenzene sulfonate and ammonium persulfate as emulsifier and oxidant, respectively. The structure and morphology of the composites were characterized by Fourier transform infrared (FTIR) spectroscopy, x-ray diffraction (XRD), and scanning electron microscopy (SEM). The FTIR and XRD results indicated that there existed an interaction between PANI molecules and SiC particles. The SEM results indicated that SiC particles were covered with the conducting PANI. Microwave absorbing properties were investigated by measuring complex permittivity and complex permeability at 26.5–40 GHz. The results showed that the reflection loss (RL) properties of PANI/SiC composites exhibited significant improvements compared with pure SiC. A maximum RL of −36.3 dB was observed at 38.6 GHz with a thickness of 0.9 mm for the composites and the effective absorption band under −10 dB reached 6.2 GHz.

Effect of temperature on the morphologies and electrochemical properties of polyaniline-gold fibrillar nanocomposites

The polyaniline-gold (PANI-AuNPs) fibrillar nanocomposites were prepared via a simple one-pot 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.

The effect of H2O2/Fe2+ catalytic oxidation system on the morphology, structure and properties of flake-like poly(2,3-dimethylaniline)

In this work, flake-like poly(2,3-dimethylaniline) (P(2,3-DMA)) with enhanced thermal stability and anticorrosive ability was synthesized by in situ polymerization using H2O2/Fe2+ catalytic oxidation system, comparing with traditional oxidant ammonium persulfate (APS) synthetic method. The structure and morphology of the samples were characterized Fourier transform infrared (FTIR) spectra, X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM). The experimental results demonstrated that using H2O2/Fe2+ catalytic oxidation system was more inclined to form the two-dimensional P(2,3-DMA) flakes. The enhancement in thermostability and corrosion resistance was attributed to the formation of phenazine-like structures in the polymer chains, which could serve as templates to form the flake-like morphology. In addition, using H2O2/Fe2+ catalytic oxidation system is more environmental friendly than the APS method that can avoid ammonium pollution on aquatic life as well as waters.

Conjugated system in metal-free 1D polyaniline nanotubes/carbon nitride hollow composites with strong adsorption and enhanced visible-light photocatalytic activities

Metal-free 1D polyaniline nanotubes/carbon nitride (PNCN) hollow composites are fabricated by self-assembly chemisorption and solvent evaporation method for the first time. The results show that carbon nitride (g-C3N4) is successfully covered onto polyaniline (PANI) nanotubes. Due to similar electronic structures of nitrogen-rich materials of PANI and g-C3N4, the combination of two π-conjugated system not only benefits the separation of photogenerated charge carriers but also increases the light absorption range of g-C3N4. The compact contact of the PANI nanotubes and g-C3N4 nanosheets as well as their matched energy level is the determinant factor for interfacial heterojunction. Specially, the hollow 1D “Janus” heterojunction impels photogenerated charge pairs to separate and transfer to opposite directions in a short diffusion path, with the additional benefits of exposure of more active sites and transmission of reactants for catalytic surface reactions. As expected, PNCN composites are photoactive and exhibit enhanced photocatalytic performance under visible-light irradiation over pure g-C3N4 and PANI nanotubes. In addition, PNCN composites possess strong adsorption capacity. This versatile 1D PNCN hollow composites prepared from a cost-effective and green process have potential applications in catalysis, drug delivery system, sensors, and energy storage and conversion.

Effect of a constant magnetic field (0.4 T) on electromagnetic properties of chiral polyaniline

Chiral polyaniline doped with d-camphorsulfonic acid (d-CSA) (PANI-(d-CSA)) was synthesized by in situ polymerization in the presence of a constant magnetic field (0.4 T). The micromorphology, conductivity, and electromagnetic properties of chiral polyaniline were systematically investigated using scanning electron microscopy, electrochemical workstation, four-point probe conductivity measurements, and a vector network analyzer. The results showed that when compared with PANI-(d-CSA)-O synthesized in the absence of a magnetic field, PANI-(d-CSA)-M synthesized in the presence of a magnetic field had increased length–diameter ratio, higher conductivity, and stronger electromagnetic loss property. The minimum reflectivity of PANI-(d-CSA)-M reduced by 21.78% and the bandwidth of microwave absorption (reflection loss < −10 dB) of PANI-(d-CSA)-M increased 4.7 times.