Formation mechanism of a nanotubular polyanilines prepared by an emulsion polymerization without organic solvent

New Inverse Emulsion-Polymerized Iron/Polyaniline Composites for Permanent, Highly Magnetic Iron Compounds via Calcination

The hydrophilic initiator potassium persulfate (KPS) was converted into a hydrophobic molecule by complexing with cetyltrimethylammonium bromide (CTAB) at both ends of the molecule (CTAPSu). Inverse emulsion polymerization thus proceeded inside micelles dispersed in the affluent toluene with CTAPSu as the initiator. Polyaniline (PANI) formed inside the micelles and entangled with Fe₃O₄ nanoparticles already esterified with oleic acid (OA). Iron composites consisted of OA-esterified Fe₃O₄ nanoparticles covered with PANI after de-emulsification. After calcination at 950 °C in an argon atmosphere, the resultant iron compound was a mixture of α-Fe (ferrite) and Fe₃C (cementite), as determined by X-ray diffraction. Eventually, the calcined iron compounds (mixtures) demonstrated superparamagnetic properties with a high saturation magnetization (Ms) of 197 emu/g, which decayed to 160 emu/g after exposure to the atmosphere for four months.

Superparamagnetic, High Magnetic α-Fe & α″-Fe16N2 Mixture Prepared from Inverse Suspension-Polymerized Fe3O4@polyaniline Composite

Oleic acid (OA)-modified Fe₃O₄ nanoparticles were successfully covered with polyanilines (PANIs) via inverse suspension polymerization in accordance with SEM and TEM micrographs. The obtained nanoparticles were able to develop into a ferrite (α-Fe) and α″-Fe₁₆N₂ mixture with a superparamagnetic property and high saturated magnetization (SM) of 245 emu g⁻¹ at 950 °C calcination under the protection of carbonization materials (calcined PANI) and other iron-compounds (α″-Fe₁₆N₂). The SM of the calcined iron-composites slightly decreases to 232 emu g⁻¹ after staying in the open air for 3 months. The calcined mixture composite can be ground into homogeneous powders without the segregation of the iron and carbon phases in the mortar without significantly losing magnetic activities.

Some Important Issues of the Commercial Production of 1-D Nano-PANI

One-dimensional polyaniline nano-materials (1-D nano-PANI) have great promise applications in supercapacitors, sensors and actuators, electrochromic devices, anticorrosive coatings, and other nanometer devices. Consequently, commercial production of 1-D nano-PANI at large-scale needs to be quickly developed to ensure widespread usage of this material. Until now, approaches—including hard template methods, soft template methods, interfacial polymerization, rapid mixing polymerization, dilute polymerization, and electrochemical polymerization—have been reported to be used to preparation of this material. Herein, some important issues dealing with commercial production of 1-D nano-PANI are proposed based on the complexity of the synthetic process, its characters, and the aspects of waste production and treatment in particular. In addition, potential solutions to these important issues are also proposed.

Efficient Synthesis of Nanostructured Poly(aniline-co-m-aminobenzoic acid) Copolymer in Presence of DBSA Surfactant

A new series of novel nanostructured poly (aniline-co-m-aminobenzoic acid) copolymer has been synthesized by chemical oxidative in-situ polymerization method using dodecylbenzene sulphonic acid (DBSA) as a soft template. The synthesized copolymers were characterized by Fourier Transform Infrared spectroscopy, Ultraviolet visible spectroscopy, X-ray diffraction and scanning electron microscopy. The infrared spectrum shows the characteristic peaks confirming the formation of the copolymer. The ultraviolet visible spectrum shows the π to π∗ transition and n to π∗ transition. X-ray diffraction pattern confirms the amorphous nature of the polymer. Scanning electron microscopic images show the new morphology of spherical granular sponge like structures in the range of 100 to 200 nm. Conducting properties of the copolymers were studied using four probe method. Copolymers doped with DBSA showed an increased conductivity in the order of 10–4 S/cm. These copolymers are found to be more soluble in polar solvents comparing to polyaniline homopolymer.

Facile synthesis of high-concentration, stable aqueous dispersions of uniform silver nanoparticles using aniline as a reductant

A facile method was developed for preparing uniform silver nanoparticles with small particle sizes of less than 10 nm at high concentrations, in which aniline was used to reduce silver nitrate (AgNO(3)) to silver nanoparticles in the presence of dodecylbenzenesulfonic acid (DBSA) as a stabilizer. Upon the addition of excess NaOH to the DBSA-aniline-AgNO(3) (DAA) system, the formation of silver nanoparticles was almost complete in just 2 min at 90 °C (in 94% yield). The average size of those resultant silver nanoparticles was 8.9 ± 1.1 nm, and the colloids were stable for more than 1 year at ambient temperature. A possible mechanism for the formation of silver nanoparticles was proposed to be related to two factors: one was the mesoscopic structures of the DAA system in which silver ions were restricted in the dispersed phases composed of DBSA and aniline; the other was Ag(2)O nanocrystallites generated in situ that could be readily reduced by aniline to small silver nanoparticles at high concentrations.

Synthesis and characterization of "hairy urchin"-like polyaniline by using β-cyclodextrin as a template

A novel synthesis of "hairy urchin"-shaped polyaniline (PAni) and its surface coverage with nanospikes was achieved from a simple microemulsion polymerization technique in the presence of β-cyclodextrin (β-CD). The rodlike micelle phase was characterized, and the key factors affecting the formation of PAni nanostructures were systematically examined. Ferric chloride (FeCl(3)) has played a role as a structural directing agent to fabricate the polymer as hairy urchin-like structure/nanorods via a cooperative interaction between FeCl(3) and DoTAC in an aqueous medium. Host-guest inclusion complex of β-cyclodextrin with aniline was used as a monomer. It has been revealed that the formation of the supramolecular complexes of polyaniline with β-CD due to host-guest interaction is indispensable for the fabrication of these unique PAni nanostructures, and a suitable β-CD to aniline molar ratio is essential to their exclusive formation. Different varieties of PAni nanostructures such as hairy urchin, branched particles consisting of rodlike branches, and regular rodlike particles were obtained in the presence of FeCl(3). Also, in the absence of FeCl(3), a predominant product of regular spherical particles and wirelike aggregation exhibiting faceted surfaces were obtained. The structures of polyaniline hairy urchin-like nanorods were analyzed using transmission electron microscopy (TEM). The synthesized polymer was characterized by Fourier-transform infrared spectroscopy and X-ray diffraction technique. Additionally, the relationship between the morphology and the conductivity of the PAni nanostructures was investigated as well.