| Summary: | A review of sensors for carbon dioxide and oxygen, with special focus on optical sensors, is presented in Chapter 1. The major experimental procedures and materials used in the PhD research project are given in Chapter 2. The results of a study of the use of different plasticisers, including phosphate-, phthalate- and adipate-based types for the creation of a range of colourimetric plastic film sensors for carbon dioxide are reported in Chapter 3. The response characteristics, <I>i.e.</I>, carbon dioxide sensitivity and the response/recovery times are studied when different types of plasticiser are used in the formulation of a sensor for carbon dioxide. Of the types of plasticisers used in this work, the most efficient appeared to be phosphate-based. Chapter 4 describes the results of an investigation of the response characteristics, <I>i.e.</I>, carbon dioxide sensitivity, temperature and response/recovery characteristics, of a plastic film colourimetric sensor for carbon dioxide when a small amount of aromatic alcohol, such as <I>m</I>-cresol, is included in the film formulation. The effects on the carbon dioxide sensitivity containing different aromatic alcohols is also examined. Chapter 5 investigates the luminescent ruthenium ion-pair [Ru(dpp)<SUB>3</SUB><SUP>2+</SUP>(Ph<SUB>4</SUB>B<SUP>-</SUP>)<SUB>2</SUB>] incorporated into the hydrophobic medium of the polymer, poly(vinyl chloride), plasticised with tributyl phosphate. A detailed study on the response characteristics, <I>i.e.</I>, film sensitivity towards oxygen and response and recovery times, were studied as a function of plasticiser content, temperature and stability in use, and with age. The major response characteristics depend very strongly upon the overall level of plasticiser present in the film. In Chapter 6, pyrene is incorporated into a number of polymer-plasticiser encapsulation media for the creation of a new range of luminescent plastic film sensors for optical sensing of oxygen. Furthermore, pyrene and Reichardt's dye are used as single polarity probes of the encapsulation medium in an attempt to correlate the oxygen-sensitivity of a pyrene-based oxygen sensor and the encapsulating medium polarity.
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