The role of acidic m-cresol in polyaniline doped by camphorsulfonic acid

Self-powered PtNi-polyaniline films for converting rain energy into electricity

Developing novel rainwater energy harvesting beyond conventional electricity is a promising strategy to address the problems of the energy crisis and environmental pollution. In this current work, a class of self-powered PtNi and optimal PtNi-polyaniline (PANI) films are successfully developed to convert rainwater into electricity for power generation. The maximized current, voltage and power of the self-powered PtNi-PANI films are 4.95 μA per droplet, 69.85 μV per droplet and 416.54 pW per droplet, respectively, which are attributed to the charging/discharging electrical signals between the cations provided by the rainwater and the electrons offered by the films. These results indicate that the optimized signal values are highly dependent on the elevated electron concentration of films, as well as the concentration, radius and charge of ions in rainwater. This work provides fresh insights into rain energy and enriches our knowledge of how to convert renewable energy into electricity generation.

Enhanced Thermoelectric Performance of Carbon Nanotubes/Polyaniline Composites by Multiple Interface Engineering

Here, we put forward an effective strategy to regulate the interface structure of carbon nanotubes/polyaniline (CNTs/PANI) composite films and improve their thermoelectric (TE) properties by sequential dedoping-redoping treatment. Dedoping induces conductive resistance-undoped PANI to enhance the energy barrier between CNTs and PANI, leading to a greatly increased Seebeck coefficient and deteriorated conductivity. Subsequently, upon the redoping process, the electrical conductivity is dramatically improved owing to the generated conductive PANI chains, while Seebeck coefficient is maintained at 90% of the dedoped composites. This yields a significantly improved power factor of 407 μW m^-1 K^-2 from the as-prepared composites (234 μW m^-1 K^-2), which is the highest value among those of all the reported CNTs/PANI composites. The outstanding TE performanceis probably ascribed to the multiple interface structure of the PANI composite generated from incomplete dedoping and redoping processes, contributing to the enhanced carrier-filtering effect to retain a relatively high Seebeck coefficient and efficient charge transport to improve conductivity. Furthermore, the flexible TE device generates a high power of 1.5 μW at ΔT = 50 K, demonstrating the applicability of this composite for energy-harvesting electronic devices.

Synthesis and effect of secondary dopant on the conductivity of conducting polymer polyaniline

Polyaniline (PANI) in its emeraldine salt form was synthesized by chemical method from aniline monomer in the presence of HCl mixed with LiCl and ammonium persulfate as oxidant. Then, a portion of sample was dedoped with NH3 solution and another equal portion was separately postdoped with secondary dopants, such as H2SO4 and HClO4, respectively. Finally, the dried samples of PANI prepared in all its three different forms (emeraldine salt form, undoped emeraldine base, and the two secondary doped forms of PANI) were characterized by UV-visible spectroscopy, cyclic voltammetry (CV) techniques, Fourier transform infrared (FT-IR) spectroscopy, and electrical conductivity measurement. The cyclic voltammograms of PANI in its emeraldine base (PANI-EB) determined the electrochemical behavior and the growth mechanisms of the polymer. The FT-IR and UV-vis spectra confirmed the expected structural modification up on doping, undoping, and postdoping processes of the polymer. Their measured electrical conductivities were from 0.02 for undoped, 156 for primary doped form, and increasing from 158 to 257 S/cm for those secondary doped PANI. The influence of secondary doping on the electrical conductivity was also investigated from their spectroscopic data which shows dramatic rise in conductivity. The result also shows that secondary doping increased the π conjugation.

Conducting Polyaniline Nanowire and Its Applications in Chemiresistive Sensing

One dimensional polyaniline nanowire is an electrically conducting polymer that can be used as an active layer for sensors whose conductivity change can be used to detect chemical or biological species. In this review, the basic properties of polyaniline nanowires including chemical structures, redox chemistry, and method of synthesis are discussed. A comprehensive literature survey on chemiresistive/conductometric sensors based on polyaniline nanowires is presented and recent developments in polyaniline nanowire-based sensors are summarized. Finally, the current limitations and the future prospect of polyaniline nanowires are discussed.

Facile synthesis of water-dispersible conducting polymer nanospheres

Water-dispersible polypyrrole nanospheres with diameters of less than 100 nm were synthesized in high yield without any templates, surfactants, or functional dopants by the introduction of 2,4-diaminodiphenylamine as an initiator into a reaction mixture of pyrrole monomer, oxidant, and acid. The initiator plays a critical role in tailoring the nanostructures of polypyrrole. 2,4-Diaminodiphenylamine interacts with acid to form cations, which combine with various anions to self-assemble resulting in different size nanomicelles. These nanomicelles, stabilized by initiator molecules, act as templates to encapsulate pyrrole and oxidant leading to the formation of nanospheres during polymerization. When smaller acids are used, smaller diameter sphere-like polypyrrole nanostructures are obtained. The as-synthesized polypyrrole nanospheres can then be used to fabricate highly conducting nitrogen-doped carbon nanospheres with controllable sizes of 50-220 nm with monodispersities up to 95% after pyrolysis. The size of the carbon nanospheres decreases by 20-30 nm due to carbonization when compared to the original polymer nanospheres. The molecular structures, morphologies, and electrical properties along with the formation mechanism of the polypyrrole and carbon nanospheres are discussed.

Polyaniline nanoparticle-carbon nanotube hybrid network vapour sensors with switchable chemo-electrical polarity

Chemo-resistive sensors were prepared from monodisperse poly(aniline) nanoparticles (PaniNP) synthesized via oxidative dispersion polymerization. Poly(styrene sulfonic acid) (PSSA) was used as the stabilizer and dopant agent. PaniNP transducers were assembled by spraying layer by layer a solution containing different concentrations of PaniNP and multi-wall carbon nanotubes (MWNT) onto interdigitated electrodes. This process led to stable sensors with reproducible responses upon chemical cycling. Chemo-electrical properties of these sensors have been investigated in sequential flows of pure nitrogen and nitrogen saturated with a set of volatile organic compounds (VOC). Interestingly the sensing mode of PaniNP transducers (the NVC or PVC effect) can be switched simply by increasing PaniNP content or by the addition of only 0.5% of MWNT to reach a resistance lower than 150 Omega. Due to their original conducting architecture well imaged by atomic force microscopy (AFM), i.e. a double percolated conductive network, PaniNP-MWNT hybrids present both higher sensitivity and selectivity than other formulations, demonstrating a positive synergy. Mechanisms are proposed to describe the original chemo-electrical behaviours of PaniNP-based sensors and explain the origin of their selectivity and sensing principle. These features make them attractive to be integrated in e-noses.