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Title: Expanding the scope of free-radical dispersion polymerisation in supercritical carbon dioxide
Author: McAllister, Thomas D.
ISNI:       0000 0004 6494 4633
Awarding Body: University of Nottingham
Current Institution: University of Nottingham
Date of Award: 2017
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Electrophoretic displays (EPD) show several advantages over other display screen types including being easy on the eye, low power consumption, good visibility in bright daylight and a wide viewing angle. However, conventional EPDs only offer black and white images. One possible approach to colour EPD is the use of coloured particles. Here, the colours that can be displayed are dictated largely by the colour of the colloidal particles dispersed within the screen, which are traditionally carbon black and titanium dioxide white. In this thesis, dispersion polymerisation of methyl methacrylate (MMA) in supercritical carbon dioxide (scCO2) is investigated as a simple route to producing functional particles for application in colour EPDs. First, using a commercially available poly(dimethyl siloxane) PDMS based stabiliser, multi-stage injections are used in order to allow greater particle size control than previously published for any single stabiliser, producing particles between 309 and 3966 nm in diameter. Particle size distributions (PDI) of ~1.5 were consistently obtained for particles synthesised using this process. The method was then adapted in order to allow the incorporation of acid and base functionalised monomers in order to aid particle charging as well as acrylic dyes for colour. Analysis of these particles revealed that various core-shell structures were achieved and could be influenced by solvent and monomer choice. Finally, dyed particles synthesised using the techniques developed during this project were assessed for their ability to function in EPDs. Colour switching was successful and synthesis in scCO2 was shown to yield better separation of the white and coloured states of the test cells than those produced by analogous synthesis in conventional media.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: QD241 Organic chemistry