Date of Award

6-2002

Document Type

Thesis

Degree Name

Master of Materials Science and Engineering (MMatSE)

Department

Materials Science

First Advisor

Dr. Ahmed Galal Helmy

Second Advisor

Dr. Kamal Mohammed Sayed khalil

Third Advisor

Dr. Mamdouh Ahmed Abdel Rehim

Abstract

Conducting polymers emerged as a new class of materials by the end of the sixties. Since then many efforts have been made to put these materials to

industrial use. Among the achievements are their applications in the semiconductor industry, medical field, chemical and biological sensors, etc. A

different track that alleviated the prospects of the application of conducting

polymers is the modification of the polymer film, namely through the inclusion of metallic moieties for specific target usage. In this thesis the candidate aimed

to synthesis well established and extensively studied class of electrically conductive polymer, 3-methylthiophene. The polymer was then subjected to a

modification by an inorganic component. The work was intended to examine the evolution of several properties upon the inorganic component inclusion

within the polymer film matrix. Basically, one of the achieved goals is the hybridisation of the two phases in a semi-quantitative protocol. Conducting polymer films were electro-synthesized and the film thickness was varied depending on the amount of charge used. The modification of the polymer films was achieved by the application of an inorganic layer by dip-coating the film-covered substrate in an electrolyte prepared via sol- gel process.

The electrical properties of the prepared films were examined by running electrochemical impedance spectroscopy experiments. The experimental data, thus obtained were then fitted using numerical/graphical methods of some equivalent circuits. The films were tested in contact with organic and aqueous medium. The data were compared and analysed using the suggested equivalent circuit models. The inorganic film material, the polymer films, and the "modified" organic-inorganic film hybrids were further investigated using thermo-gravimetric, Fourier Transform infrared spectroscopic, scanning electron microscopy, and x-ray diffraction analyses.

The hybrid films possessed improved electrical properties, namely increased capacitance. The film hydrophilic property affected the

electronic/ionic conduction when examining the film in water vs. acetonitrile.

A proposed model in which the inorganic layer provides a surplus of charge storage at the film/electrolyte boundaries to high capacitance "inner" organic

layer is suggested. This model is more accepted especially in the case where the polymer film is less conductive and when the ionic diffusion is restricted. Unique hybrid film morphologies were found to depend on the thickness of the

polymer film and the time needed to deposit the inorganic layer. Phase separation between the organic polymer film and the inorganic layer was

realized when inorganic deposition time was minimum. Inorganic particle size ranged between 20 nm and few mm. Thermal gravimetric analysis proved that

the inclusion of the inorganic layer stabilized the thermal degradation of the film. The presence of the iron-doped silica based inorganic moieties was confirmed from the EDXA and XRD measurements. On the molecular level, infrared spectroscopy data showed silicon and iron oxide vibrations and confirming the inclusion of the inorganic layer within the polymer m

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