M. Sh. Zoromba

Novel and economic acid-base indicator based on (p-toluidine) oligomer: Synthesis; characterization and solvatochromism applications

A new (p-toluidine) oligomer (PTO) was facile synthesized and economically routed via chemical oxidative polymerization by potassium dichromate as an initiator in an acidic aqueous medium at room temperature. The characterization of (p-toluidine) oligomer (PTO) has been described by various techniques including Fourier transform infra-red (FTIR), UV-Visible measurements, Mass spectra, H NMR, and thermal gravimetric analysis (TGA). Solvatochromism of PTO was studied in different polaritiy solvents such as acetic acid, acetone, dimethyl formamide, ethanol, isopropanol, chloroform, p-xylene, dichloromethane and carbon teterachloride. The absorption bands were bathochromically shifted with increased polarity of the solvent (positive solvatochromism). PTO shows three isosbestic points at 333, 388 and 472nm in a binary mixture of acetone and chloroform. The deprotonation constants of PTO were found to be 3.1 and 5.8, based on spectrophotometric calculations. PTO was successfully used as an acid-base indicator; the acid solution color sharply turned from pink (acidic medium) to yellow (basic medium) at the end point.

Facile synthesis and fabrication of a poly(ortho-anthranilic acid) emeraldine salt thin film for solar cell applications

Poly(o-anthranilic acid) emeraldine salt (PANA-ES) as a conjugated semiconductor polymer has been synthesized in an acidic medium based oxidative polymerization route. The identification of the PANA-ES powder has been carried out using the following techniques: FT-IR and UV-Vis. SEM has been used to investigate the morphology of the resulting PANA-ES powder. The structural properties of the resulting nanostructured PANA-ES thin film have been investigated by X-ray diffraction (XRD). The analysis of the spectral behavior characteristics of the nanostructured PANA-ES thin film, in the absorption region, displayed a direct and indirect allowed transition, and the fundamental energy gaps were estimated as (1.89, 3.24 eV) and (2.35, 4.06 eV), respectively. A hybrid (polymer/inorganic) heterojunction device built on PANA-ES (deposited by the spin coating technique onto a p-Si single crystal wafer) was fabricated. The dark I–V characteristics were determined at different temperatures in the range from 298 to 386 K of the Au/PANA-ES/p-Si/Al heterojunction diode. The device showed rectification behavior and an ideality factor of 85 at ±2 V and 3.229 determined at room temperature. Under the following different light intensities: 10.1, 15.3 and 20.5 W m−2, the Au/PANA-ES/p-Si/Al showed photovoltaic performance data with a short circuit current (Isc) and open circuit voltage (Voc) of (0.09 mA 1,41 mV), (0.16 mA, 176 mV) and (0.26 mA and 211 mV), respectively. The filling factor (FF) and electrical conversion efficiency (η) of the Au/n-PANA-ES/p-Si/Al device were found to be 0.205 and 6.07%, respectively.

Characterization of Vinyl Ester/Jute Fiber Bio-Composites in the Presence of Multi-Walled Carbon Nanotubes

In this study, vinyl ester –Jute fiber biocomposites were prepared using vacuum-assisted resin infusion (VARI) process. Woven Jute fibers were used with mass fraction 0.68. Multi-walled carbon nanotubes (MWCNTs) are added to the resin with weight ratio 0.5: 99.5 to investigate the thermo-mechanical properties of bio-composites. Storage and loss modulus of vinyl ester bio-composites were investigated in the presence MWCNTs over a range of temperature (25 to 160 oC) to measure the capacity of bio-composite to store and dissipate energy. Damping properties of vinyl ester bio-composites were studied in terms of tan (d). Viscoelastic test using dynamic mechanical analysis (DMA) showed that the glass transition temperature increases with the addition of MWCNTs up to 112.4 oC. Addition of jute fiber reinforcements improves the storage modulus value of vinyl ester more than 65% at room temperature. Significant improvement in storage modulus was found in the presence of MWCNTs.