The mechanism of the oxidative polymerization of aniline and the formation of supramolecular polyaniline structures

Assembly of viral hydrogels for three-dimensional conducting nanocomposites

M13 bacteriophages act as versatile scaffolds capable of organizing single-walled carbon nanotubes and fabricating three-dimensional conducting nanocomposites. The morphological, electrical, and electrochemical properties of the nanocomposites are presented, as well as its ability to disperse and utilize single-walled carbon nanotubes effectively.

Investigation of Electron Transfer by Geobacter sulfurreducens Biofilms by using an Electrochemical Quartz Crystal Microbalance

Both the short- and long-term electron-transfer processes of electrode-respiring Geobacter sulfurreducens biofilms are demonstrated by using an electrochemical quartz crystal microbalance (QCM). The QCM monitors the frequency shift from the initial resonant frequency (background) in real time, while the current increases, because of biofilm growth. In the short term, the frequency shift is linear with respect to current for the biofilm. In long-term biofilm growth up to the exponential phase, a second linear region of frequency shift with respect to current is observed. In addition to the frequency shift response at constant polarization, the frequency shift response is coupled to cyclic voltammetry experiments. During cyclic voltammetry, a reproducible, negative increase in frequency shift is observed at oxidizing potentials. The results suggest that a QCM can be used in applications in which it is useful to find the most efficient current producer.

Synthesis and application of hybrid polymer composites based on silver nanoparticles as corrosion protection for line pipe steel

A facile method was developed to synthesize in high yield dispersed silver nanoparticles (AgNPs) with small particle sizes of less than 10 nm. Silver nitrate was reduced to silver nanoparticles by p-chloroaniline in the presence of polyoxyethylene maleate 4-nonyl-2-propylene-phenol (NMA) as a stabilizer. The produced AgNPs were used to prepare hybrid polymer based on N-isopropylacrylamide (NIPAm), 2-acrylamido-2-methylpropane sulfonic acid (AMPS), N,N-methylenebisacrylamide (MBA) and potassium persulfate (KPS) using a semi-batch solution polymerization method. The prepared AgNPs and hybrid polymer were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM). The corrosion inhibition activity of the AgNPs and hybrid polymer towards steel corrosion in the presence of hydrochloric acid has been investigated by polarization and electrochemical impedance spectroscopy (EIS) methods. Polarization measurements indicate that the AgNPs and hybrid polymer acts as a mixed type-inhibitor and the inhibition efficiency increases with inhibitor concentration. The results of potentiodynamic polarization and EIS measurements clearly showed that the inhibition mechanism involves blocking of the steel surface by inhibitor molecules via adsorption.

Fluoroplast-polyaniline-coated adsorbent for one-step isolation of DNA for PCR detection of viral hepatitides (HBV and TTV)

AIMS

To demonstrate the effectiveness of application of the adsorbent successively modified with nano-layers of fluoroplast and polyaniline for one-step isolation of DNA of hepatitis B virus and transfusion-transmitted virus from human serum.

MATERIALS & METHODS

The technique is based on the application of the spin-cartridges containing porous adsorbent for one-step viral DNA isolation from serum followed by polymerase chain reaction.

RESULTS

The developed adsorbent was shown to be effective for one-step isolation of viral DNA from serum samples for polymerase chain reaction diagnostics.

CONCLUSION

The effectiveness of the developed adsorbent application for isolation of viral DNA from serum for polymerase chain reaction diagnostics was confirmed in comparison with standard methods. Thus, the facile sample preparation method of viral DNA isolation was elaborated.

X-band microwave absorption and dielectric properties of polyaniline-yttrium oxide composites

This article highlights the microwave absorption and dielectric attributes of synthesized polyaniline (PAni)-yttrium trioxide (Y2O3) composites. Temperature-dependent conductivity measurements were carried out in the temperature range of 300–473 K, which indicates the presence of hopping conduction. The PAni-Y2O3 composites showed semiconductor behavior with the exponential variation of inverse temperature dependence of electrical conductivity. Microwave measurements were carried out in the X-band (8–12 GHz) frequency; the composites exhibit absorption-dominated shielding effectiveness (SEA) in the range -33 to -35 dB (>99% microwave attenuation) and minimum electromagnetic reflection. The ε′ and ε″ values of the composites are in the range of 81.5–97.5 and 80–118.5, respectively. The PAni-Y2O3 composites showed significant improvement in microwave SE and complex permittivity of the composites, indicating the influence of Y2O3 in PAni.

High-yield synthesis of poly(m-phenylenediamine) hollow nanostructures by a diethanolamine-assisted method and their enhanced ability for Ag+ adsorption

DEA induces the formation of PmPD hollow nanostructures which exhibit improved adsorption performance.

Highly homogeneous core–sheath polyaniline nanofibers obtained by polymerisation on a wire-shaped template

Homogeneous and defect-free PANI nanofibrous membranes were demonstrated with oxidative polymerization on a Nylon 6 electrospun wire-shaped template.

Fabrication and evaluation of polyaniline nanofibers via ethyl cellulose template

The template method for polymerization has high potential for synthesizing polymer nanotubes, nanofibers, and nanobelts because it controls the diameter and length of the material microstructure. In this study, polyaniline (PANI) nanofibers were successfully prepared with ethyl cellulose as the template. The chemical constituents and crystallinity of the PANI nanofiber samples were investigated by Fourier transform infrared spectroscopy and x-ray powder diffraction. Sample morphology was characterized by scanning and transmission electron microscopy. The size uniformity and electrical conductivity of the PANI nanofibers were also determined. The electrical conductivity of the PANI nanofibers reached up to 13.5 S cm−1 at a hydrochloric acid concentration of 1 mol L−1. The PANI nanoparticles had uniform size, and the PANI nanofibers were disordered. The mechanism of ethyl cellulose as a template for synthesizing PANI nanofibers was also analyzed. This study provides a simple method for synthesizing uniform conductive PANI nanofibers.

Formation of poly(methyl methacrylate) thin films onto wool fiber surfaces by vapor deposition polymerization

Chemical vapor deposition (CVD) polymerization is a useful technique because of the possibility of forming very thin film of pure polymers on substrates with any geometric shape. In this work, thin films of poly(methyl methacrylate) or PMMA were formed on the surfaces of wool fabrics by a CVD polymerization process. Various polymerization initiators including dicumyl peroxide, tert-butyl peroxide, and potassium peroxydisulfate have been investigated to polymerize methyl methacrylate onto the surfaces of wool by the CVD polymerization. The wool fabrics were impregnated with initiators and were then exposed to MMA monomer vapor under vacuum at the boiling temperature of the monomer. Wool fabrics with vapor-deposited PMMA surfaces were characterized by elemental analysis, TGA, FTIR, disperse dye absorption, contact angles measurement, AFM, and SEM. PMMA-coated wool fabrics showed higher contact angle and absorbed more dyes than that of the control wool. It was evident from the results obtained by various characterization techniques that MMA was successfully polymerized and formed thin films on the surfaces of wool fabrics by all initiators investigated but the best results were achieved with tert-butyl peroxide.

Electrically conductive polyaniline/polyimide nanofiber membranes prepared via a combination of electrospinning and subsequent in situ polymerization growth

Highly aligned polyimide (PI) nanofiber membranes have been prepared by electrospinning equipped with a high speed rotating collector. As the electrospun polyimide nanofiber membranes possess large surface area, they can be used as the template for in situ growth of polyaniline (PANi) by using FeCl₃ as the oxidant. It is found that PANi nanoparticles can be uniformly distributed on the surface of highly aligned PI nanofibers due to the low oxidization/reduction potential of FeCl₃ and the active nucleation sites of the functionalized PI nanofibers. The as-prepared PANi/PI composite membranes not only possess excellent thermal and mechanical properties but also show good electrical conductivity, pH sensitivity and significantly improved electromagnetic impedance properties. This is a facile method for fabricating high-performance and multifunctional composites that can find potential applications in electrical and aerospace fields.

Oriented arrays of polyaniline nanorods grown on graphite nanosheets for an electrochemical supercapacitor

Oriented arrays of polyaniline (PANI) nanorods grown on expanded graphite (EG) nanosheets are fabricated by in situ polymerization to achieve excellent electrochemical properties for applications as supercapacitor electrodes. EG serves as an excellent 3D conductive skeleton that supports a highly electrolytic accessible surface area of redox-active PANI and provides a direct path for electrons. The porous and ordered nanostructure provides a larger contact surface area for the intercalation/deintercalation of protons into/out of active materials and shortens the path length for electrolyte ion transport. The maximum specific capacitance of 1665 F g(-1) at 1 A g(-1) is observed in the PANI/EG electrode with 10% EG content. The composite electrode material also exhibits significant rate capability and good long-term cycling stability. The results demonstrate that PANI is effectively utilized with the assistance of EG conductive skeletons in the electrode. Such 3D composite nanoarchitecture is very promising for the next generation of high-performance electrochemical supercapacitors.

Reversible control of electrochemical properties using thermally-responsive polymer electrolytes

A thermally responsive copolymer is designed to modulate the properties of an electrolyte solution. The copolymer is prepared using pNIPAM, which governs the thermal properties, and acrylic acid, which provides the electrolyte ions. As the polymer undergoes a thermally activated phase transition, the local environment around the acid groups is reversibly switched, decreasing ion concentration and conductivity. The responsive electrolyte is used to control the activity of redox electrodes with temperature.

Use of facile mechanochemical method to functionalize carbon nanofibers with nanostructured polyaniline and their electrochemical capacitance

A facile approach to functionalize carbon nanofibers [CNFs] with nanostructured polyaniline was developed via in situ mechanochemical polymerization of polyaniline in the presence of chemically treated CNFs. The nanostructured polyaniline grafting on the CNF was mainly in a form of branched nanofibers as well as rough nanolayers. The good dispersibility and processability of the hybrid nanocomposite could be attributed to its overall nanostructure which enhanced its accessibility to the electrolyte. The mechanochemical oxidation polymerization was believed to be related to the strong Lewis acid characteristic of FeCl3 and the Lewis base characteristic of aniline. The growth mechanism of the hierarchical structured nanofibers was also discussed. After functionalization with the nanostructured polyaniline, the hybrid polyaniline/CNF composite showed an enhanced specific capacitance, which might be related to its hierarchical nanostructure and the interaction between the aromatic polyaniline molecules and the CNFs.