Identifier

etd-1113102-112657

Degree

Master of Science in Chemical Engineering (MSChE)

Department

Chemical Engineering

Document Type

Thesis

Abstract

Polysilanes are ¥ò-conjugated conductive polymers with a one-dimensional Si backbone and organic substituted side chains. The conventional Wurtz-type coupling reaction has been used for preparing various alkyl substituted polysilanes, i.e. poly(di-n-hexyl)silane and poly(hexylmethyl)silane. For each polysilane examples with methoxy (-OCH3) and allyl (-CH2CH=CH2) end caps have been prepared. The solution UV absorption characteristics of the polysilanes at room temperature have been measured, from which the wavelength maximum of the UV-VIS absorption and the absorptivity have been obtained. Allyl end capped polysilanes have the same wavelength maximum as methoxy end capped polysilanes. However, the absorptivities of allyl end capped polysilanes are always higher than those of the methoxy end capped polysilanes, presumably as a result of the fact that they contain fewer defects. The conformation of poly(di-n-hexyl)silanes with methoxy end caps and polysilanes with allyl end caps in polymer networks has been studied. The polymer networks have been obtained by cross-linking vinyl terminated poly(dimethyl)siloxanes and methylhydrosiloxane-dimethylsiloxane copolymers. The correlation between the mechanical properties of the composites and the conformation of the polysilanes in the composites has been studied using rheology and UV-VIS spectroscopy. It has been determined that the conformation of poly(di-n-hexyl)silane is dependent on the flexibility of poly(di-n-hexyl)silane/polysiloxane composites. In addition, the thermochromism of the polysilane/polysiloxane composites has been studied. Noticeable differences in the transition behavior have been observed in comparison to polysilanes in solution and the solid state. The reduced degree of conformational freedom of the polysilanes results in different transition temperatures and a shoulder at longer wavelength at high temperature.

Date

2002

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Thomas J. Cleij

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