Ayşegül Gök

Synthesis and Characterization of Polyindole/Poly(vinyl acetate) Conducting Composites

Composites of a polyindole (PIN) and poly(vinyl acetate) (PVAc) were prepared chemically using FeCl3 as an oxidant agent in anhydrous media. The composite compositions were altered by varying the indole monomer during preparation. The composites were characterized by FTIR and UV‐visible spectroscopies, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), stress‐strain experiments and conductivity measurements. Moreover, the film of PVAc and PIN/PVAc composites were prepared by casting on glass Petri dishes to examine their stress‐strain properties. PIN/PVAc composites are thermally more stable than PIN. It was found that the conductivities of PIN/PVAc composites depend on the indole content in the composites.

Synthesis and Characterization of Polyvinylferrocene/Polypyrrole Composites

Conducting polymer composites of polyvinylferrocene and polypyrrole (PVF/PPy) were synthesized chemically by the in situ polymerization of pyrrole in the presence of PVF using FeCl3 as oxidant. Acetic (CH3COOH) and boric (H3BO3) acids were used as the synthesis medium. Effects of the synthesis medium on the properties of the PVF/PPy composite were investigated. The PVF/PPy composites and homopolymers were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and magnetic susceptibility techniques. Conductivity measurements were performed using the four‐probe technique. We found that the conductivities of PVF/PPy‐H3BO3 (1.19 S cm−1) and PVF/PPy‐CH3COOH (4.5×10−1 S cm−1) increased relative to those of the homopolymers of PPy‐H3BO3 (2.1×10−2 S cm−1) and PPy‐CH3COOH (1.2×10−2 S cm−1) due to the interaction of PVF with the pyrrole moiety. The stability of all homopolymers and composites were investigated by thermogravimetric analysis and by conductivity measurements during heating‐cooling cycles. There was a small drop in conductivity caused by the annealing of PVF/PPy composites at 70°C. The conductivity of all samples increased with temperature and exhibited stable electrical behavior with increasing temperature. TGA analysis of samples showed that the composites were more stable than the homopolymers or PVF separately. The magnetic susceptibility values of samples were negative, except for PVF/PPy‐H3BO3. Morphology changes of the composites investigated by scanning electron microscopy (SEM), attributed to synthesis conditions, have a significant effect on their conductivity.

Conducting Polyaniline Sensors for Some Organic and Inorganic Solvents

Abstract 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.

Preparation and Characterization of Poly(2-halogenaniline) Composites with Al2O3, SiO2, and Red Mud

Abstract In-situ polymerizations were carried out in the presence of Al2O3, SiO2, and red mud (RM) (host materials) to synthesize poly(2-halogenaniline)/Al2O3, poly(2-halogenaniline)/SiO2, 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, Al2O3, 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.

Electrorheological Properties of Polyaniline/Red Mud Composite

Abstract In this study, electrorheological (ER) properties of polyaniline (PANI) and polyaniline/red mud (RM) composites were investigated. Polyaniline and polyaniline/red mud (PRM) composites were prepared by oxidative polymerization. PANI and PRM particle-based ER suspensions were prepared in silicone oil (SO) and their ER behavior was investigated as a function of concentration, shear rate, electric field strength, frequency, and temperature. Sedimentation stabilities of these suspensions were determined. ER activities of all the suspensions were observed to increase with increasing electric field strength, dispersed particle concentration, and decreasing shear rate. The suspensions show shear thinning non-Newtonian viscoelastic behavior, in which viscosity of suspension decreases with increasing shear rate. Shear stress of composite suspensions increases linearly with increasing applied electric field strength and concentration of the particles. Effect of high temperature on ER activity of ER fluids system was also investigated.

Atmospheric Pressure Plasma Deposition of Polyfuran

Summary form only given. The atmospheric pressure plasma polymerization of furan was carried out with the objective of synthesizing polvfuran film. RF (13.56 MHz) plasma electrical characteristics and optical characteristics are examined. The structure, compositions and morphology of the plasma deposited poly furan film were investigated by Fourier transform infrared (FTIR), atomic force microscopy (AFM), ultravioletvisible absorption spectroscopy (IJV-vis) and thermogravimetric analysis (TGA). The formation of polyfuran was confirmed using FTIR and UV-visible analysis. The properties of plasma-deposited polvfuran were compared with those of chemicallv synthesized polyfuran. Although the plasma deposited polyfuran shows lower thermal stability than that of chemicallv synthesized polyfuran, it has better solubility in common solvents.