dc.contributor.author | Bourque, Alexander | |
dc.date.accessioned | 2014-04-04T14:57:37Z | |
dc.date.available | 2014-04-04T14:57:37Z | |
dc.date.issued | 2014-04-04 | |
dc.identifier.uri | http://hdl.handle.net/10222/49088 | |
dc.description | An assessment of the thermochromic behaviour of three-component chemical systems comprising a colour-changing leuco dye, an electron-accepting phenolic developer, and a long-chain alkyl alcohol solid solvent. | en_US |
dc.description.abstract | Thermochromic materials undergo temperature-dependent colour changes. Although there are several origins of thermochromism, two distinct types of thermochromism are common in thermochromic mixtures. Melt-lightened thermochromism occurs when the colour density of a mixture decreases with increasing temperature, and is usually associated with colour loss upon mixture melting. Melt-darkened thermochromism occurs when the colour density of a mixture increases with increasing temperature, and is usually associated conversion from a decoloured solid state to a coloured melt.
Three-component thermochromic systems generally consist of a leuco dye (minor component), a phenolic colour developer (intermediate component), and a high melting-point organic solvent (dominant component). In these systems, the colouring behaviour is controlled by competing binary interactions, with the dye:developer interaction responsible for colour formation and the developer:solvent interaction responsible for colour erasure.
In the present study, three-component mixtures composed of CVL (dye), long-chain alkyl gallates (phenolic developer), and long-chain alkyl alcohols (long-chain solvent) were examined. The thermochromic behaviour (i.e., melt-lightened vs. melt-darkened thermochromism) of these mixtures was examined as a function of the matching of the alkyl chain length of the gallate developer and alcohol solvent. When the alkyl chain lengths were well matched, the developer:solvent interaction dominated in the solid state and melt-darkened thermochromism was observed. When the alkyl chain lengths were poorly matched, the dye:developer interaction dominated in the solid state, and melt-lightened thermochromism was observed. The colour density of the molten state was determined by the developer:dye molar ratio, with high molar ratios yielding coloured melts and low molar ratios yielding decoloured melts.
Additional studies employing chemically dissimilar developers and solvents (e.g., bisphenol A with 1-hexadecanol) yielded mixtures that displayed optimal melt-lightened thermochromism. The high solid-state colour density due to weak developer:solvent interactions provides further evidence that competing binary interactions are responsible for the colouring behaviour observed for three-component thermochromic systems.
Ternary thermochromic phase diagrams were used to define compositional regions of optimal thermochromic behaviour (i.e., high colour contrast), providing a useful experimental tool for the rapid identification of ideal sample compositions. Additionally, an examination of the properties of thermally erasable ink-jet printer inks was carried out during the present study. | en_US |
dc.language.iso | en | en_US |
dc.subject | Thermochromism | en_US |
dc.subject | Leuco Dyes | en_US |
dc.subject | Colour chemistry | en_US |
dc.subject | Polymorphism | en_US |
dc.title | Investigations of Reversible Thermochromism in Three-Component Systems | en_US |
dc.date.defence | 2014-03-27 | |
dc.contributor.department | Department of Chemistry | en_US |
dc.contributor.degree | Doctor of Philosophy | en_US |
dc.contributor.external-examiner | Dr. Bart Kahr | en_US |
dc.contributor.graduate-coordinator | Dr. Mark Stradiotto | en_US |
dc.contributor.thesis-reader | Dr. D. Jean Burnell | en_US |
dc.contributor.thesis-reader | Dr. Jeff. R. Dahn | en_US |
dc.contributor.thesis-reader | Dr. Peng Zhang | en_US |
dc.contributor.thesis-supervisor | Dr. Mary Anne White | en_US |
dc.contributor.ethics-approval | Not Applicable | en_US |
dc.contributor.manuscripts | Not Applicable | en_US |
dc.contributor.copyright-release | Yes | en_US |