Ayse Gul Yavuz

The effect of synthesis media on the properties of substituted polyaniline/chitosan composites

Substituted polyaniline/chitosan (sPANI/Ch) composites were chemically synthesized in H(2)SO(4) and CH(3)COOH synthesis media. Structural and physical properties of the composites were characterized by using FTIR, SEM, TGA, UV-vis, XRD techniques, and conductivity measurements. The effect of synthesis media on morphology, thermal stability, conductivity, and crystalline properties was investigated. Chemical interactions between substituted polyanilines and chitosan were explained using FTIR spectra results. The different morphological surfaces were observed in SEM images of the composites. The size of the substituted polyaniline/chitosan (sPANI/Ch) composites was in nanoscale, and the composites synthesized in acetic acid media showed smaller structures than those of H(2)SO(4) media and pure chitosan. It was interpreted from XRD results that the composites have amorphous structure and the PNEANI/Ch-CH(3)COOH composite has the highest crystallinity.

Some Novel Conducting Polythiophene Derivatives: Theoretical Analysis, Synthesis, Characterization and Electroreological Properties

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.

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.