This study focuses on the electrochromic device (ECD) applications of poly(3,4‐ethylenedioxythiophene)/tungsten oxide (PEDOT/WO3) hybrid nanofibers prepared via electrospinning method. Nanoporous WO3 films were initially electrosynthesized on Pt sheet. The PEDOT layer was electropolymerized onto the entire surface of the WO3 nanoporous host framework in the presence of different ionic liquids: 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4), 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6), 1‐butyl‐ 3‐methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIMTFSI), and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPTFSI). The morphological features and elemental surface characterization of hybride nanofibers were monitored by scanning electron microscopy and energy dispersive X‐ray spectroscopy. ECDs changed color reversibly from transparent to light brown by switching from +3 V to −3 V. It was found that the highest optical modulation of 47.89 % and maximum coloration efficiency of 363.72 cm2/C is achieved for PEDOT/WO3/BMIMPF6 based electrochromic device. Hybrid nanofibers exhibited excellent long term stability even after 1000 chronoamperometric cycles. This work could not only push forward the facile preparation of PEDOT/WO3 nanofibers but also represent, for the first time, the possibility that the hybrid nanofibers could be a promising material for the highly efficient ECDs.

A facile approach of polypyrrole (PPy)/tungsten oxide (WO3) composites electrosynthesized in ionic liquids for fabrication of electrochromic devices is discussed. The electrochromic properties of PPy/tungsten oxide nanocomposite films (PPy/WO3) prepared in the presence of four different ionic liquids, 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIMBF4), 1‐butyl‐3‐methylimidazolium hexafluorophosphate (BMIMPF6), 1‐butyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl) imide (BMIMTFSI), and 1‐butyl‐1‐methylpyrrolidinium bis(trifluoromethylsulfonyl) imide (BMPTFSI) were investigated in detail. Cyclic voltammetry results revealed that PPy/WO3 nanocomposite films have much more electrochemical activity than those of WO3 and PPy film. The electrochromic contrast, coloration efficiency, and switching speed of the composite films were determined for electrochromic characteristics. The maximum contrast and the maximum coloration efficiency values were measured as 33.25% and 227.89 cm2/C for the PPy/WO3/BMIMTFSI composite film. Copyright © 2015 John Wiley & Sons, Ltd.

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In this study, the effects of silane‐treated nano‐CaCO3 particles on the flexural, Mode‐I, Mode‐II and interlaminar shear strength (ILSS) properties of carbon fiber/epoxy composites are investigated experimentally. The surface of nano‐CaCO3 particles is treated with a silane coupling agent, namely, (3‐Glycidyloxypropyl) trimethoxysilane (GPTMS). Three‐point bending, double cantilever beam (DCB), end‐notch flexure (ENF), and short beam shear (SBS) tests are carried out on the prepared composite specimens according to the relevant ASTM requirements. The results show that with the dispersion of 5 wt% silane‐treated nano‐CaCO3 particles the flexural modulus, flexural strength, Mode‐I fracture toughness, Mode‐II fracture toughness, and ILSS values can be enhanced by 16.8%, 13.6%, 25.7%, 19.6%, and 19.8%, respectively, compared to reference composites. The storage modulus is also increased by about 15.3% with the silane‐treated nano‐CaCO3 particles. The silane‐treated nano‐CaCO3 particles had no significant effect on the glass transition temperature of the composites.

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