Ayşegül Gök

To investigate the effects of surfactants on the properties of polyaniline (PANI), a series of PANIs was synthesized in the presence of surfactants by chemical polymerization of aniline in an acidic medium, using (NH₄)₂S₂O₈ as oxidant. Three types of surfactant were used: (i) non‐ionic poly(ethylene oxide) (20) sorbitan monolaurate (Tween 20) and poly(ethylene oxide) (20) sorbitan monopalmitate (Tween 40); (ii) cationic (1‐tetradecyl)trimethylammonium bromide; and (iii) anionic sodium 1‐dodecanesulfonate and sodium 1‐pentanesulfonate. The structural, morphological and thermal properties of the various samples were characterized using Fourier transform infrared and UV‐visible spectroscopy, scanning electron microscopy and thermogravimetric analysis. Calorimetry was used to compare enthalpy changes during polymerization. The electrochemical and glucose biosensor properties of the PANIs were investigated using cyclic voltammetry and amperometric measurements. PANI‐Tween 20 and PANI‐Tween 40 were found to be good for immobilization of glucose oxidase enzymes and potential candidates for use in glucose biosensing. Copyright © 2010 Society of Chemical Industry

A series of alternating phylene and symmetrically bithiophene containing repeat units and the respective homopolymers have been synthesized and characterized by combining FTIR, UV-Vis spectroscopy, four probe conductivity measurement, TGA and SEM analysis. Quantum mechanical calculations of the structures and infrared spectra of the monomers and respective dimers were compared with experimental results. The polymers are soluble in N-methyl-pyrrolidone (NMP). The samples have conductivities of 10⁻⁵ S/cm levels. Thermal degradation analysis results indicated that poly-bithiophene derivatives have higher thermal stabilities than poly-monothiophene derivatives. All samples exhibited different surface morphologies. The electrorheological (ER) properties of polymer suspensions in silicone oil were prepared and ER behavior was investigated as a function of shear rate, electric field strength and frequency.

The atmospheric pressure radiofrequency (RF) plasma polymerization of furan was carried out with the objective of synthesizing polyfuran thin film. The structure, compositions and morphology of the plasma deposited polyfuran film were investigated by Fourier transform infrared (FTIR), atomic force microscopy (AFM), ultraviolet‐visible absorption spectroscopy (UV‐vis) and thermogravimetric analysis (TGA). The formation of polyfuran was confirmed using FTIR and UV‐visible analysis. The properties of plasma‐deposited polyfuran were compared with those of chemically synthesized polyfuran. Although the plasma deposited thin film polyfuran shows lower thermal stability than that of chemically synthesized polyfuran. It has better solubility in CHCl₃, also. Thin uniform polyfuran films are obtained in plasma assisted polyfuran deposition, while particles are obtained in chemical polyfuran polymerization.

In-situ polymerizations were carried out in the presence of Al₂O₃, SiO_2, and red mud (RM) (host materials) to synthesize poly(2-halogenaniline)/Al₂O₃, poly(2-halogenaniline)/SiO_2, and poly (2-halogenaniline)/red mud composites. The 2-halogenanilines were polymerized without guest materials under the same conditions to compare the properties of the product with those of the composites. Homopolymers and composites were characterized by FT-IR and UV-vis spectroscopies, thermogravimetric analysis (TGA), scanning electron microscopy (SEM), X-ray diffraction spectroscopy, magnetic susceptibility, and conductivity measurements. The inclusion of either of those monomer units in the resultant composites was confirmed by FT-IR analysis. The properties of the composites changed depending on the type of host materials. Thermal stability of materials follows the trend according to their residual amounts at 800°C of Al₂O₃ > RM > SiO₂. The enhancements in thermal behaviors of poly(2-halogenanilines) were studied in the presence of host materials (RM, SiO₂, Al₂O₃). SEM revealed interesting morphological features of the composites prepared using various inorganic materials and monomers. The analyses indicated typical structural differences between RM, SiO₂, Al₂O_3, and poly(2-halogenanilines). Magnetic susceptibility measurements revealed that the composites with SiO₂ and Al₂O₃ have diamagnetic properties, whereas composites in the presence of RM show paramagnetic conductivity mechanism. The conductivities of composites synthesized using three different materials were measured by a four-probe technique. The presence of Al₂O₃, SiO₂, and RM affected the conductivities of pure polymers.

Polyaniline (PAn) emeraldine salts (PAn-Cl, PAn-Br, PAn-ClO₄) were synthesized by the electrochemical method using different acids (HCl, HBr, HClO₄). PAn salts in pellet form were used as sensors for organic (EtOH, CHCl₃, C₆H₆) and inorganic (HCl, NH₃) solvents. Electrical conductivity responses of PAns to five solvents were investigated. The change of electrical conductivity of PAns (Δσ), relative to the value measured before exposure, varied with the solvent used. The sensor properties of PAns varied depending on the nature of dopant anions such as the type and size. It was found that PAn-ClO₄ has the highest sensing power on HCl, NH₃, and CHCl₃, and it has the lowest sensing power on C₆H₆.

We report the synthesis and characterization of a series of conducting poly(2‐chloroaniline) (P2ClAn)/red mud (RM) nanocomposite materials. The polymerization of 2‐chloroaniline in an aqueous medium in the presence of (NH₄)₂S₂O₈ and RM resulted in the formation of a nanocomposite (P2ClAn/RM). The extent of P2ClAn loading in the composites increased with increasing oxidant and monomer concentrations but decreased with RM. The properties of the nanocomposites were characterized with Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis), conductivity measurements, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry analysis. The inclusion of P2ClAn in the composites was confirmed by FTIR studies. The UV–vis spectra of P2ClAn/RM nanocomposites were similar to that of P2ClAn. The conductivity changed in all the composites prepared under various conditions. Thermogravimetric analyses revealed the enhanced thermal stabilities of the nanocomposites with respect to P2ClAn. Morphological images of the as‐synthesized materials were also investigated with scanning electron microscopy and environmental scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006