Nanostructured Polyanilines

As for PPy s, there has been an explosion of interest in the synthesis of PAn s with nanodimensions, as such materials have been shown to have enhanced electronic and electrochemical properties. Formation of PAn nanoparticles has been achieved via polymerization in micelles, using either sodium dodecyl sulfate (SDS)211 or DBSA212 214 as the surfactant stabilizer. Particle sizes in the range of 10-30 nm with conductivities as high as 24 S cm-1 have been reported. 

Control of the micelle size utilized in the formation of PAn nanoparticles has been achieved by tailoring the stabilizer to modify the resulting micelle dimensions. Kim and coworkers215 216 used amphiphilic polymer molecules and hydrophobically end-capped polyethylene oxide) [PEO], and varied the hydrophilic regions in it to control the final micelle size. The resultant nanostructures ranged from 20 to approximately 300 nm in size, depending on the molecular weight of the hydrophilic PEO midsection. 

Physical templates have also been used to facilitate the growth of PAn nanostructures. Nanofibril arrays were prepared by chemically depositing PAn into 20-200 nm pores in anodic aluminum oxide film (30-60 pm thick) that was subsequently etched away with 0.3 M H3P04or through ultrasonication.221 

Hollow CEP cigar-shaped nanotubes with sealed ends, synthesized via the track-etched polycarbonate template route, have also been reported by Mativetsky and Datars.222 These materials exhibited a small drop in conductivity as the diameter decreased from 400 to 50 nm, contrary to previous reports.223 224The small decrease 

Choi and Park226 have modified surfaces with cyclodextrins to assist in the electroformation of PAn nanowires. Others have utilized the concept of molecular templates to form PAn supramolecular rods with electrical conductivity improved by two orders of magnitude.227 

---

Figure 4. Cyclic voltammograms of nanostructured polyaniline composite films in strong acid solutions (aq. HC1 or H2S04) (a) GCE PANI/PVS (b) Au PDMA-PSS (c) Au PANSA and (d) Pt PANI-PVS-PESA.

Cyclic nanostructured polyanilines (Figure 2.23) have been synthesized by means of a simple modified aqueous/organic interfacial polymerization with the aid of PAA [405]. The cyclic PANl nanostructures were formed by severe secondary overgrowth through the electrostatic interaction between anihne/oligoaniline and PAA chains. The average diameter of the obtained cychc structure was ca. 400 nm and its conductivity was 1 S cm . ... 

Figure 2.26 SEM image of the brain-like PAN nanostructure. (Reprinted with permission from Macromolecular Rapid Communications, A new route for the preparation of brain-like nanostructured polyaniline by Y. Zhu, J. Li, M. Wan et ai., 28, 1339-1344. Copyright (2007) Wiley-VCH)...

H. Qiu and M. Wan, Synthesis, characterization, and electrical properties of nanostructural polyaniline doped with novel sulfonic acids (4- n-[4-(4-nitrophenylazo)phenyloxy]alkyl] aminobenzene sulfonic acid), J. Polym. Sci. Part A Potyrrc Chem., 39, 3485-3497 (2001). 

Z. Zhang and M. Wan, Composite films of nanostructured polyaniline with poly(vinyl alcohol), Synth. Met., 128, 83-89 (2002). 

J. Yang, Y. Ding, and J. Zhang, Uniform rice-like nanostructured polyanilines with highly crystallinity prepared in dodecylbenzene sulfonic acid micelles. Mater. Chem. Phys., 112, 322-324 (2008). 

U. Riaz, S. Ahmad, and S. M. Ashraf, Comparison of corrosion protective performance of nanostructured polyaniline and poly(l-naphthylamine)-based alkyd coatings on mild steel. Mater. Corn, 60, 280-286 (2009). 

J. Huang, S. Viiji, B. H. Weiller, and R. B. Kaner, Nanostructured polyaniline sensors, Chem. 

Figure 17.3 ESR spectra of nanostructured polyaniline samples (each of 10 mg) prepared at different potential scan rates (1) 6, (2) 12, and (3) 60 mV s (Reprinted with permission from Journal of Physical Chemistry B, Spectral Characteristics of Polyaniline Nanostructures Synthesized by Using Cyclic Voltammetry at Different Scan Rates by Shaolin Mu et al., 112, 37, 11558-11563. Copyright (2008) American Chemical Society)...

Gupta V. and Miura N., High performance electrochemical supercapacitor from electrochemically qmthesized nanostructured polyaniline. Mater. Lett., 2006,60,1466-1469. 

The effect of loading (0.5,1.0 and 2.0 wt%) nanostructured polyaniline (PANI) on the physiochemical, physicomechanical, morphological and thermal properties of soybean oil-based polyester nanocomposites has also been reported. The nanocomposites of conjugated linseed oil, acrylic acid and divinylbenzene are synthesised using modified montmoriUonite clay. The resultant nanocomposites exhibit a storage modulus in the range of 17-79 MPa at the glass transition temperature compared to the pristine polymer which is 2.1 MPa. The nanocomposites show better thermal stability (up to 200°C) than the pristine polymer. 

J. Alam, U. Riaz and S. Ahmad, Nanostructured polyaniline reinforced sustainable resource (soy oil alkyd) based composites , Polym Compos, 2010, 31, 32-7. 

S. M. Ashraf, S. Ahmad and U. Riaz, Development of sustainable resource-based nanostructured polyaniline/castor oil polyurethane composites , Adv Polym Technol, 2009, 28, 26-31. 

Mishra AK, Ramaprabhu S (2012) Nanostructured polyaniline decorated graphene sheets for reversible CO2 capture. J Mater Chem 22 3708-3712... 

FTO fluorine-doped tin oxide films, PVP poly(4-vinylphenol), Au-PVS/N-PANI gold electrode modified with LbL film of poly(vinyl sulfonic acid) (PVS) and nanostructurated polyaniline (N-PANI)... 

Dhawale DS, Vinu A, Lokhande CD (2011) Stable nanostructured polyaniline electrode for... 

---