Presence Of Β-naphthalene Sulfonic Acid Research Articles

Morphology transition control of polyaniline from nanotubes to nanospheres in a soft template method

A soft template route is reported for the fabrication of polyaniline nanospheres via the oxidative polymerization of aniline in the presence of β-naphthalenesulfonic acid (β-NSA) as both surfactqant and dopant, and ammonium persulfate as oxidant at 2–5 °C. Control over the morphology and size of the nanoparticles was achieved by changing the reaction medium via addition of an organic cosolvent (i.e. ethanol or ethylene glycol) and by controlling the concentrations of aniline and β-NSA and the molar ratio of β-NSA to aniline. By this means the size of the β-NSA–aniline micelles and the way that aniline monomer interacts with the micelles were controlled. In fact the lower dielectric constant of organic cosolvent, due to reduction of the possibility of dissociation of ionic species, causes the monomer to exist mostly as neutral aniline molecules rather than as anilinium cations. The neutral aniline molecules form aniline-filled micelles with β-NSA, which act as soft templates for the formation of polyaniline nanospheres. Scanning and transmission electron microscopies, dynamic light scattering, and Fourier transform infrared and UV-visible spectroscopies were used to characterize the products. The mechanism of morphology transition from nanotubes to nanoparticles is discussed based on the experimental observations. © 2014 Society of Chemical Industry

Synthesis and Structural and Electrical Characteristics of Polypyrrole Nanotube/TiO2 Hybrid Composites

Hybrid composites of conducting polypyrrole nanotubes with TiO2 nanoparticles were synthesized in the presence of β-naphthalenesulfonic acid by chemical oxidative polymerization. The morphology, structure, and electrical properties were investigated by several experimental techniques. The results indicated that the structural and electrical properties of the composites were influenced by the content of TiO2 nanoparticles. The DC conductivity of the composites increased by one order of magnitude when the concentration of TiO2 was 0.1 M compared with pure PPy nanotubes. AC conductivity of the composites showed the similar trend with the TiO2 content and obeyed the power law index in the 101–107 Hz range. The electrorheological properties of the composite under steady and oscillatory shear were also evaluated.

Core–shell structured and electro-magnetic functionalized polyaniline composites

Core–shell structured and electro-magnetic functionalized polyaniline (PANI) composites were chemically prepared by micro-spherical hydroxyl iron (Fe(OH)) magnet as the hard-template associated with a self-assembly process in the presence of β-naphthalene sulfonic acid (β-NSA) as the dopant. Field emitting scanning electron microscope (SEM) and transmission electron microscope (TEM) measurements indicate that the electro-magnetic functionalized PANI–β-NSA/Fe(OH) composites have a novel core–shell structure, in which micro-spherical Fe(OH) magnet (0.5–5 μm in diameter) is as the core, and self-assembled PANI–β-NSA nanofibers (30–50 nm in diameter) formed on the surface of the Fe(OH) microspheres is as the shell (60 nm in thickness). Moreover, the electro-magnetic properties of the core–shell micro/nanostructured composites are adjustable by changing the ratio of Fe(OH) to aniline monomer.

The electrocatalytic oxidation of ascorbic acid on polyaniline film synthesized in the presence of β-naphthalenesulfonic acid

Abstract Polyaniline–β-naphthalenesulfonic acid composite film on platinum electrode surface has been synthesized via the electrochemical polymerization of aniline in the presence of β-naphthalenesulfonic acid (NSA). FT-IR, UV-vis and electrochemical characterization indicate the formation of the doped polyaniline. Further investigations found that the polyaniline (PAN) doped with NSA extended the electroactivity of PAN in neutral and even in alkaline media. The PAN–NSA composite film coated platinum electrodes are shown to be good electrocatalytic surfaces for the oxidation of ascorbic acid (AA) in phosphate buffer solution (PBS) of pH 7.0. The anode peak potential of AA shifts from 0.62 V at bare platinum electrode to 0.34 V at the PAN–NSA composite modified platinum electrode with greatly enhanced current response. A linear calibration graph is obtained over the AA concentration range of 5–60 mM using cyclic voltammetry. The kinetics of the catalytic reaction is investigated using rotating disk electrode (RDE) voltammetry, cyclic voltammetry and chronoamperometry. The results are explained using the theory of electrocatalytic reactions at chemically modified electrodes. The PAN–NSA composite film on the electrode surface shows good reproducibility and stability.

Unusual polymer dispersions—polypyrrole suspensions made of rings, frames, and platelets

Experimental results show that the polymerization of pyrrole in the presence of β-naphthalenesulfonic acid and different fluorosurfactants like perfluorooctanesulfonic acid, perfluorooctyldiethanolamide, and ammonium perfluorooctanoate leads to polypyrrole with special morphologies, such as rings or disks and rectangular frames or plates. The formation of these unusually shaped particles of polymer dispersions is explained by the chemical and colloidal peculiarities of the oxidative pyrrole polymerization with ammonium peroxodisulfate in aqueous medium.

Polyaniline/TiO2 Composite Nanotubes

Polyaniline (PANI) composite nanotubes (90−130 nm in diameter) containing titanium dioxide (TiO2) nanoparticles (about 10 nm in diameter) were synthesized through a self-assembly process in the presence of β-naphthalenesulfonic acid (β-NSA) as the dopant. It was found that the morphology, size, conductivity, and hydrophobicity of the PANI−β-NSA/TiO2 composite nanotubes were affected by the content of TiO2 nanoparticles in the nanotubes. The micelles composed of β-NSA anions and anilinium cations containing TiO2 were proposed to interpret the formation mechanism of the self-assembled composite nanotubes. The Raman spectra and X-ray diffraction characterizations show that the main chain of the composite nanotubes is identical to that of the doped PANI, and indicate that there is no chemical interaction between PANI and TiO2.

Self-assembled conducting polypyrrole micro/nanotubes

Self-assembled polypyrrole (PPy) micro/nanotubes, whose diameters androom temperature conductivities were within the ranges of 50–2000nm and 2–40 S cm−1 respectively, were successfully synthesized bya chemical and electrochemical method in the presence of β-naphthalene sulfonicacid or p-toluenesulfonateacid as the dopant. By changing the polymerization method and conditions aswell as dopant structures, one can control the morphology, size and electricalproperties of the doped PPy. It was proposed that dopant micelles orpyrrole/dopant clusters act as templates in the formation of the micro/nanotubes.

Nanostructures of polyaniline composites containing nano-magnet

With an average diameter of 80–100 nm, nanostructures (nanorods or nanotubes) of polyaniline (PANI) composites containing Fe 3O 4 nanoparticles ( d≈10 nm) were prepared by a template-free method in the presence of β-naphthalene sulfonic acid (NSA) as a dopant. PANI–NSA/Fe 3O 4 nanostructures exhibited a superparamagnetic behavior (i.e. no hysteresis loop) and their conductivity was around 10 −2 S/cm. However, it was found that the electrical and magnetic properties of PANI–NSA/Fe 3O 4 nanostructures could be adjusted by changing the content of Fe 3O 4 nanoparticles in the composites. A template-like model was proposed to interpret the formation of the nanostructures.

Formation Mechanism of Self-Assembled Polyaniline Micro/Nanotubes

Self-assembled micro/nanotubes (650−76 nm in diameter) of polyaniline (PANI) were synthesized in the presence of β-naphthalene sulfonic acid (β-NSA) as a dopant. It was found that the diameter and room-temperature conductivity of the PANI−NSA tubes decreased with the decrease of the molar ratio of β-NSA to aniline. On the bases of the results obtained from X-ray diffraction (XRD) and dynamic lighting scattering (DLS), it was proposed that when the molar ratio of β-NSA to aniline was high (e. g. 2), the NSA−An salt precipitate formed by β-NSA and aniline played a “template-like” role in forming the PANI−NSA tubes, while the “template-like” role was played by the NSA−An micelle when the ratio is low (e.g., 1/2 or 1/4).

Composite films of nanostructured polyaniline with poly(vinyl alcohol)

The uniform composite films of nanostructured polyaniline (PANI) (e.g. nanotubes or nanorods with 60–80 nm in diameter) were successfully fabricated by blending with water-soluble poly(vinyl alcohol) (PVA) as a matrix. The PANI nanostructures were synthesized by a template-free method in the presence of β-naphthalene sulfonic acid (β-NSA) as a dopant. The molecular structures of PANI–β-NSA and the related composite films were characterized by UV–Vis absorption spectrum, FTIR spectrum and X-ray diffraction. It was found that the electrical, thermal and mechanical properties of the composite films were affected by the content of nanostructured PANI–β-NSA in the PVA matrix. The composite film with 16% PANI–β-NSA showed the following physical properties: room-temperature conductivity is in the range 10 −2 S/cm, tensile strength ∼603 kg/cm 2, tensile modulus ∼4.36×10 5 kg/cm 2 and ultimate elongation ∼80%.

Studies on formation mechanism of polypyrrole microtubule synthesized by template-free method

The influence of the polymerization time and rate as well as the solution's ionic strength on the morphology, conductivity, and molecular structure of the polypyrrole (PPy) microtubule [synthesized by the template-free method in the presence of β-naphthalene sulfonic acid (β-NSA) as the dopant] were investigated. It was found that the formation of the PPy-NSA microtubule was a slow and self-assembled growth process. Moreover, the β-NSA dopant played a “templatelike” role in the formation of tubular PPy-NSA, which might be relative to its surfactant characters. This assumption was further confirmed by the phenomenon that the morphology of PPy-NSA could be modified by increasing the ionic strength by adding inorganic salt. © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 997–1004, 2001

Microtubules of polypyrrole synthesized by an electrochemical template­free method

Microtubules of polypyrrole (PPy) were synthesized by an electrochemical template-free method in the presence of β-naphthalenesulfonic acid (β-NSA) as a dopant for the first time. The influence of electrochemical polymerization conditions, such as material of the working electrode, the concentration of β-NSA and pyrrole monomer, current density and polymerization time on the tubular morphology of PPy-NSA was systematically investigated. PPy-NSA tubules 0.8–2.0 µm in diameter and 15.0–30.0 µm in length were obtained when a non-corrosive steel plate was used as the working electrode, and the size of the tubules was affected by other polymerization conditions. The molecular structure of the tubules was characterized by FTIR and X-ray diffraction, indicating that their polymer chains are similar to granular PPy synthesized by other chemical or electrochemical methods, and the tubules were amorphous. The conductivity of the tubules at room temperature was found to be about 5.0 S cm−1 and the temperature dependence of the conductivity followed a two-dimensional Variable Range Hopping (2D-VRH) model. It was proposed that the absorbed micelles of β-NSA, which result from the surfactant characteristics of β-NSA dopant on the working electrode, act like templates in forming PPy-NSA tubules by this new method.

Tubular polypyrrole synthesized byin situ doping polymerization in the presence of organic function acids as dopants

Tubular polypyrrole (PPy) could be synthesized by in situ doping polymerization in the presence of β-naphthalene sulfonic acid (NSA) as dopant. The resultant tubular PPy–NSA not only exhibits high room temperature conductivity (ςRT = 10 S/cm) but is also soluble in m-cresol. The molecular structure of PPy–NSA is identical to the characteristic structure of PPy synthesized by a conventional method. It has been demonstrated that NSA dopant with large molecular size and plate–lebe structure is a key factor to control formation of tubular PPy–NSA. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1443–1449, 1999