Thesis (MSc)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: The primary objective of the work was to investigate the negative thermal
expansion of organic materials and to determine the mechanisms governing
this phenomenon by using the principles of crystal engineering. To this end,
the following three compounds were studied in detail:
• 4,4'-Diiodobiphenyl
• 4-Iodobenzoic acid
• Methyl Paraben
The rationale behind this work was to determine the mechanisms responsible
for the observed negative thermal expansion and to uncover the structural
factors that induce negative thermal expansion. Single-crystal X-ray
diffraction was employed as the primary analytical tool, owing to the unique
information it can provide regarding intermolecular interactions in the solid
state.
A total of twenty organic compounds were analysed, of which three
exhibited negative thermal expansion. Each compound employs a specific
mechanism for negative thermal expansion, two of which are closely related
and the third distinct. / AFRIKAANSE OPSOMMING: Die hoof doel van hierdie studie was om ondersoek in te stel in die verskynsel
van ‘negative thermal expansion’ in organiese materiale en gevolglik die
meganisme vas te stel deur die beginsels van kristalmanipulsie (‘crystal
engineering’) te gebruik. Gevolglik was drie organise stowwe ondersoek:
• 4,4'-Diiodobiphenyl /4,4'-Diiodobifeniel
• 4-Iodobenzoic acid /4-Iodobensoësuur
• Methyl Paraben
Die redenasie hieragter is om die meganisme verantwoordelik vir die
‘negative thermal expansion’ vas te stel en die verskillende faktore wat bydra
tot dit te bevestig. Enkel-kristal diffraksie word benut as die primêre
analitiese tegniek as gevolg van die unieke inligting wat verkry kan word met
betrekking tot die intermolekulêre interaksies.
'n Totaal van twintig stowwe is geanaliseer waarvan drie die spesifieke
termisie eienskap besit. Elk van die drie stowwe het ‘n ander meganisme te
vore laat kom waarvan twee baie ooreenstem en die derde verskil.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/6896 |
| Date | 03 1900 |
| Creators | Greyling, Guillaume Hermanus |
| Contributors | Barbour, L. J., Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | Stellenbosch University |
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