Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT:
The use of various ‘smart materials’ (briefly meaning materials that respond to a change in
their environment) is currently of interest to both academics and industry. The primary aim of
the current study was to entrap photochromic (PC) dyes in miniemulsions, as a means to
improve their fatigue resistance, thus synthesizing smart nanoparticles. In the coatings industry
the use of aqueous systems is becoming a common requirement for health and environmental
reasons.
Miniemulsion entrapment allows the direct dispersion of PC dyes into aqueous systems while
allowing for the opportunity to tailor-make the host matrix in order to obtain a suitable PC
response and improved fatigue resistance.
The optimal instrument set-up required to establish the PC response of films of the so-called
smart nanoparticles (i.e. PC miniemulsions) was determined. A UV-Vis instrument with a
chip-type UV LED mounted inside for activation of the samples provided PC response results.
A tungsten lamp with filter provided deactivation of the samples.
A stable butyl methacrylate (BMA) miniemulsion formulation was established by conducting a
design of experiments. A chromene and spironapthoxazine (SNO) PC dye were entrapped in
the BMA miniemulsion. A hindered amine light stabiliser (HALS) was also entrapped with the
SNO dye in the BMA miniemulsion to further improve the fatigue resistance. The following
PC properties of the smart nanoparticles films were evaluated: colourability, thermal decay
rate, half-life and fatigue resistance. To compare results with conventional systems, a BMA
solution polymer was prepared. The SNO dye and different concentrations of the HALS were
mixed with the BMA solution polymer.
In comparison to the SNO smart nanoparticles the chromene smart nanoparticles films had
lower colourability, but better fatigue resistance.
Incorporating HALS at levels of 0.5–2% in the BMA miniemulsion with PC dye did not lead
to any significant improvement in fatigue resistance, yet films of the BMA solution polymer
showed some improvement.
SNO dye incorporated at 1% gave similar colourability in both miniemulsion and in solution
polymer, yet the fatigue resistance of the films of the PC miniemulsions was much better. / AFRIKAANSE OPSOMMING:
Die gebruik van verskeie “slim materiale’ (kortliks beskryf as materiale wat reageer op `n
verandering in hul omgewing) is tans van belang vir beide akademici en die industrie. Die hoofdoel
van hierdie studie was om miniemulsietegnologie te gebruik om fotochromiese (FC) kleurstowwe
vas te vang, vir die sintese van slim nanopartikels, om sodoende die weerstand teen afgematheid te
verbeter. In die verfindustrie word die gebruik van waterbasissisteme meer algemeen weens
gesondheids- en omgewingsredes.
Die gebruik van miniemulsie sisteme om materiale vas te vang maak dit moontlik om FC
kleurstowwe direk in waterbasissisteme te meng. Die sintese van `n unieke gasheer matriks word
benodig om die optimum FC verandering te toon en weerstand teen afgematheid te verbeter.
Om die FC verandering van die sogenaamde slim nanopartikel films (d.w.s. FC miniemulsies) te
ondersoek was `n gepaste instrumentele opstelling nodig. Dit is vasgestel dat `n UV-Vis instrument
waarin `n skyfie-tipe UV LED gemonteer is vir aktivering van die monsters, reproduseerbare
resultate gegee het. Die monsters is gedeaktiveer deur gebruik te maak van `n tungsten lig met ‘n
filter.
`n Eksperimentele ontwerp is toegepas om `n stabiele butielmetakrielaat (BMA) miniemulsie
formulasie te verkry. `n ‘Chromene’ en ‘spironapthoxazine’ (SNO) FC kleurstof is in die BMA
miniemulsie vasgevang tesame met `n verhinderde amien ligstabiliseerder (VALS) om die
weerstand teen afgematheid verder te verbeter. Die volgende FC eienskappe van die slim
nanopartikels is gemeet: kleurintensiteit, tempo van termiese verwering, half-lewe en weerstand
teen afgematheid. `n BMA polimeeroplossing is berei om resultate mee te vergelyk. Die SNO
kleurstof en verskillende konsentrasies van die VALS is met die BMA polimeeroplossing gemeng.
In vergelyking met die slim SNO nanopartikels het die intelligente chromene nanopartikelfilms `n
swakker kleurintensiteit gehad, maar `n hoër weerstand teen afgematheid.
Die gebruik van 0.5–2% VALS in die BMA miniemulsie met FC kleurstof het minimale
verbetering in weerstand teen afgematheid getoon, maar daar was wel `n beduidende verbetering in
die geval van films met FC kleurstof in `n BMA polimeeroplossing.
Byvoeging van 1% SNO kleurstof in `n BMA miniemulsie of polimeeroplossing het dieselfde
kleurintensiteit gelewer, maar die weerstand teen afgematheid van die FC miniemulsie was baie
beter.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/5356 |
| Date | 12 1900 |
| Creators | Koen, Yolande |
| Contributors | Sanderson, R. D., McLeary, J. B., University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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