Influence of Acidity and Oxidant Concentration on the Nanostructures and Electrochemical Performance of Polyaniline during Fast Microwave-Assisted Chemical Polymerization

Abstract

Polyaniline (PANI), a typical conducting polymer, has attracted great interest as an electrode material. A series of PANIs were prepared through fast microwave-assisted chemical oxidative polymerization with varying HCl and APS concentrations here. It was found that the microwave synthesized PANIs had ~4 times higher for the yields and 7~10 times higher for the electrical conductivity in comparison to PANI samples prepared using conventional method. PANI nanosheets could easily be fabricated in weakly acidic solution due to their oligomeric structure, which contained flat phenazine rings. By contrast, linear PANI chains produced in highly acidic solutions formed nanofibers. The APS concentration did not significantly affect the molecular structures of PANIs under the conditions here. However, increasing the concentration of APS produced nanofibers with shorter branches, which may be due to secondary nucleation during chain growth resulting from increases in active initiation centers. The electrical conductivity and electrochemical performance of PANIs were both improved with increasing HCl and APS concentrations. Improvements due to increases in HCl concentration may be attributed to additions in conjugation length and enrichment of doping levels, while improvements due to increases in APS concentration could be attributed to the increased crystallinity of PANI, which facilitates ion transport.

Recovery of Electrochemical Properties of Polyaniline-Based Multilayer Films with Improved Electrochemical Stability

“…For instance, PANI films commonly suffer from the loss of electroactivity during the repeated electrochemical tests . Many efforts have been reported to enhance the PANI stability and durability, such as doping, structural engineering, incorporating carbon-based materials or inorganic materials, and so on. − Previously, PANI multilayer films having improved electrochemical stability were fabricated using polymer dopants, showing that poly­(acrylic acid) (PAA) can improve the PANI electrochemical stability, whereas polystyrene sulfonate (PSS) enhances the conductivity and chemical stability of PANI . Even if PANI–polyacid multilayer films possess improved electrochemical stability compared to PANI homopolymers, their electroactivity characteristics still gradually degrade .…”

Acid-assisted polymerization: the novel synthetic route of sensing layers based on PANI films and chelating agents protected by non-biofouling layer for Fe2+ or Fe3+ potentiometric detection

“…For example, templated method leads to obtain multiple nanostructural polyaniline such as zero-dimentional nanospheres, one dimentional nanotubes, nanofibers and nanorods and twodimentional, nanosheets 20, 22 . However, the polyaniline produced by electrodeposition, templated method or electrospinning are limited because of their low yield and fussy postprocessing 23 . Chemical oxidative polymerization has a large potential to be used in the field of synthesis technology and recognized as the major route for producing PANI with controllable size and morphology.…”

“…20,22 However, polyanilines produced by electrodeposition, templated method or electrospinning are limited because of their low yield and fussy postprocessing. 23 Chemical oxidative polymerization has a large potential to be used in the field of synthesis technology and is recognized as the major route for producing PANI with controllable size and morphology. In this route, the evolution of polymerization can be observed.…”

Seed polymerization and capacitive performances of polyaniline nanofibers

“…In this work, we prepared polyaniline nanofibers by seed polymerization. The aniline oligomers would be produced in weak acidic solution of phosphoric acid, and then seed polymerization would be carried out in 1 M hydrochloric acid aqueous solution by adding more aniline monomers again to form highly conductive PANI nanofibers [6]. The microstructure and capacitance performances would be investigated in detail.…”