Zhitao Li

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.