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Degree

PhD, University of Cincinnati, Arts & Sciences : Chemistry, 2003.

Abstract

Poly(dimethylsiloxane) (PDMS) is a versatile silicone polymer studied very extensively for various applications. However, because of its mechanical weakness, it is filled with many different filler particles including SiO2, TiO2 and ZrO2. In the present research work, some specialty filler particles were generated by in-situ sol-gel method in PDMS networks. These composites were studied for their structure-property effects in relevance to their transparency, magnetic, electrical and mechanical properties. Structure-property and kinetic studies were performed on TiO2 and ZrO2 filled PDMS composites. Hydrolysis and condensation process was controlled by selecting alkoxides, with longer chain length and bulky side groups (titanium-2-ethyl hexoxide and zirconium butoxide). SAXS, SEM, Instron was used for characterizing these composites. Fe2O3 particles with different shapes and sizes were generated in-situ in PDMS networks using aqueous solutions of FeCl3 and HCl. Non-aqueous method and ferric acetylacetonate [Fe(acac)] however yielded higher amounts of filler. Magnetic and mechanical properties were studied using vibrating sampling magnetometer (VSM) and Instron respectively. Attenuated Total Reflectance (ATR), SEM and EDS. was used to determine the structure, shape and composition of the composite. Polyaniline (PANI) was generated in-situ from monomer aniline, by chemical oxidation in PDMS networks. The effects of temperature, dopant and oxidant were also studied. The structures of the PANIs were studied using ATR. Conductivity was measured using a four-point probe. Conductivity of this composite depends on the degree of oxidation and doping of the generated PANI. A novel approach along with a structure-property study for ZrO2 and TiO2 filled PDMS was performed. A small amount of a stannous compound mixed in alkoxide, dramatically reduced the time for particle generation. The composites were transparent, with ZrO2 filled having higher transparency than TiO2. SAXS data showed a correlation between the particles. Surface of an injection molded microfluidic component made from cyclic olefinic copolymers (COC) was modified in order to change the surface properties applicable to bio-fluidic devices. Plasma treatments and ASG (aerosol gel) coating were used to achieve the surface modifications. Structural changes after the plasma treatments were examined by ATR spectroscopy. Contact angle measurements with water were used as a measure of hydrophobicity.

Subject Headings

Chemistry, Polymer

Keywords

in situ; composites poly(dimethylsiloxanes); magnetic composites; conducting composites polyaniline; small angle x-ray scattering analysis of composites

Advisor

Dr. James E. Mark

Pages

182p.

Document number: ucin1059393661
Permalink: http://rave.ohiolink.edu/etdc/view?acc_num=ucin1059393661

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