The chemical synthesis of conductive polyaniline doped with dicarboxylic acids

Electrochemical Biosensors Based on Conducting Polymers: A Review

Conducting polymers are an important class of functional materials that has been widely applied to fabricate electrochemical biosensors, because of their interesting and tunable chemical, electrical, and structural properties. Conducting polymers can also be designed through chemical grafting of functional groups, nanostructured, or associated with other functional materials such as nanoparticles to provide tremendous improvements in sensitivity, selectivity, stability and reproducibility of the biosensor’s response to a variety of bioanalytes. Such biosensors are expected to play a growing and significant role in delivering the diagnostic information and therapy monitoring since they have advantages including their low cost and low detection limit. Therefore, this article starts with the description of electroanalytical methods (potentiometry, amperometry, conductometry, voltammetry, impedometry) used in electrochemical biosensors, and continues with a review of the recent advances in the application of conducting polymers in the recognition of bioanalytes leading to the development of enzyme based biosensors, immunosensors, DNA biosensors, and whole-cell biosensors.

Synthesis of conductive polyaniline nanofibers in one step by protonic acid and iodine doping

In this study, protonic acid and iodine-doped conductive polyaniline (PANI) nanofibers were successfully fabricated in one step using ammonium persulfate (APS) and potassium biiodate (KH(IO3)2) as the co-oxidant. The resultant PANI nanofibers were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and X-ray photoelectron spectroscopy. Their electrochemical properties were examined by cyclic voltammetry and the standard four-probe technique. Additionally, the molecular weight of the conductive PANI nanofibers was measured using a viscometer. It is found that the PANI nanofibers are codoped with protonic acid (hydrochloric acid and iodic acid) and iodine (I3 − and I5 −), and the KH(IO3)2 shows a significant acceleration effect for the oxidation polymerization of aniline. The conductivity of PANI reaches 21 S·cm−1, which is much higher than that of another PANI prepared by APS. This is ascribed to the iodine-doping effect and the nanofibers’ morphology. Additionally, the reaction mechanism of PANI is systematically discussed, and the codoped mechanism is proposed. Systematic investigations indicate that APS/KH(IO3)2 is an excellent co-oxidant for the preparation of highly conductive PANI nanofibers in one step.

Recent Progress in the Development of Conducting Polymer-Based Nanocomposites for Electrochemical Biosensors Applications: A Mini-Review

Among various immobilizing materials, conductive polymer-based nanocomposites have been widely applied to fabricate the biosensors, because of their outstanding properties such as excellent electrocatalytic activity, high conductivity, and strong adsorptive ability compared to conventional conductive polymers. Electrochemical biosensors have played a significant role in delivering the diagnostic information and therapy monitoring in a rapid, simple, and low cost portable device. This paper reviews the recent developments in conductive polymer-based nanocomposites and their applications in electrochemical biosensors. The article starts with a general and concise comparison between the properties of conducting polymers and conducting polymer nanocomposites. Next, the current applications of conductive polymer-based nanocomposites of some important conducting polymers such as PANI, PPy, and PEDOT in enzymatic and nonenzymatic electrochemical biosensors are overviewed. This review article covers an 8-year period beginning in 2010.

Filme autosuportado de polianilina desdopada para aplicações anticorrosivas

Os polímeros intrinsecamente condutores (PIC), como a polianilina (PAni), têm sido estudados com alternativa em filmes protetores de metais oxidáveis contra a corrosão. Dada a dificuldade de fusão ou dissolução da PAni para a produção de filmes, investigou-se a possibilidade de obter filmes pela mistura de PAni no estado oxidado e desdopado, conhecida como base esmeraldina, com plastificante não dopante 4-cloro-3-metilfenol (CMF) e solvente conveniente. Filmes produzidos desta forma foram caracterizados por espectroscopia FTIR e RAMAN, por TGA e ensaio de voltametria cíclica. A caracterização mostrou filmes termicamente estáveis até a temperatura de 200 ºC com indícios de interação da PAni com o CMF, com a PAni se mantendo no estado oxidado no filme produzido, condição necessária para futura aplicação como filme anticorrosivo de proteção anódica.

Preparation and characterization of composites that contain small carbon nano-onions and conducting polyaniline

Small multilayer fullerenes, also known as carbon nano-onions (CNOs; 5-6 nm in diameter, 6-8 shells), show higher reactivity than other larger carbon nanostructures. Here we report the first example of an in situ polymerization of aniline on phenyleneamine-terminated CNO surfaces. The green, protonated, conducting emeraldine polyaniline (PANI) was directly synthesized on the surface of the CNO. The functionalized and soluble CNO/PANI composites were characterized by TEM, SEM, DSC, Raman, and infrared spectroscopy. The electrochemical properties of the conducting CNO/PANI films were also investigated. In comparison with pristine CNOs, functionalized carbon nanostructures show dramatically improved solubility in protic solvents, thus enabling their easy processing for coatings, nanocomposites, and biomedical applications.

Oxidation of aniline in the presence of phenolic acids

Aniline was oxidized with ammonium peroxydisulfate (APS) in aqueous solutions of various phenolic acids: 5-sulfosalicylic acid (SSA), 3,5-dinitrosalicylic acid (DNSA) and gallic acid (GA). Polymerizations were performed at the constant molar ratios [acid]/[aniline]=0.5 and [APS]/[aniline]=1.25. The conductivity of synthesized polyaniline (PANI) is affected by the dopant anion type and decreases in order: PANI-SSA > PANI-DNSA > PANI-GA, the last polymer being nonconducting. This decrease is in accordance with the increase of initial pH value of the reaction mixture. The differences in molecular structure of synthesized PANI have been revealed by FTIR spectroscopy. FTIR spectra of PANI-SSA and PANI-DNSA show typical features of PANI conductive emeraldine salt segments. On the contrary, FTIR spectrum of PANI-GA shows absence of bands typical for conducting PANI polaronic lattice, and indicates the higher oxidation state of this polymer than that of emeraldine, the presence of substituted phenazines as constitutional units, as well as significant content of monosubstituted benzene rings which reflects low polymerization degree and/or pronounced chain branching. The strong hydrogen bonding between GA and PANI can obstruct propagation of oligoanilines and formation of longer conducting PANI chains.

Productive Synthesis and Properties of Polydiaminoanthraquinone and Its Pure Self-Stabilized Nanoparticles with Widely Adjustable Electroconductivity

Wholly aromatic poly(1,5-diaminoanthraquinone) (PDAA) particles were productively synthesized for the first time by chemically oxidative polymerization of 1,5-diaminoanthraquinone (DAA) by using CrO3, K2Cr2O7, K2CrO4, or KMnO4 as oxidants in acidic DMF. The effects of the oxidant species, oxidant/DAA ratio, polymerization temperature, and medium on the polymerization yield, macromolecular structure, size, electroconductivity, solubility, solvatochromism, thermostability, photoluminescence, and silver-ion sorption of the PDAA particles were systematically studied by IR, UV/Vis, fluorescence, and solid-state 13C NMR spectroscopies, wide-angle X-ray diffraction, scanning and transmission electron microscopies, and laser particle-size, differential scanning calorimetry (DSC), and thermal gravimetric (TG) analyses. It seems that the DAA is oxidatively polymerized at the 1,4- and 5,8-positions. Surprisingly, the chemical oxidative polymerization of DAA with CrO3 at 0 degrees C in H2SO4/DMF in the absence of external stabilizer simply affords novel PDAA nanoparticles of around 30 nm in diameter with high purity, clean surfaces, inherent semiconductivity, and self-stability that can be ascribed to the presence of a large number of 1,4-benzoquinone units that are negatively charged on their macromolecular chains. The polymers exhibit a high thermal stability at temperatures below 400 degrees C. Two unique nanoeffects were found, namely the strongest silver-ion adsorbability and photoluminescence of the PDAA nanoparticles. This gives a facile and general route for the application of the versatilities of PDAA nanomaterials. The PDAA particles are good semiconductors with a widely adjustable conductivity that moves across seven orders of magnitude through simple HClO4 redoping or Ag+ sorption, as expected.