Luminescence quenching studies of oxygen diffusion in highly permeable media

Luminescence Quenching Stuclies of ûxygen -sion in Highly Permeable Media Master of Science, 1998 Christine Jayarajah, Graduate Department of ChernistIy, University of Toronto Investigations on the nature of gas dfisivity in polymers are important not only to various industrial applications, but also to fùrther our conceptual understanding of this ubiquitous process. In this thesis, I desmie the application of a relatively new technique based on luminescence quenching to probe the nature of oxygen diaision in a series of poly[alky1(amino)thionylphosphazenes) (PTP) and high molecular weight PDMS, with varying Tg's ranging fiom -127 to 2Z0 C. Experiments performed on thin £ h s of these highly permeable media show that gas diftiisivity exhibits strong dependence on the microstructure of these polymers. The two main types of experiments under consideration are steady-state the-scan experiments and pdsed excitation experiments. While steadystate measurements provide bulk-averaged values for dfisivity and permeability, pulsed laser experiments oEer some insight into diffusivity on a microscopic scale. Attempts at the fitting of data to kinetic modeis reveal that the models applicable to quenching reactions in fluid media are incapable of rationaliong quenching in polyrneric media.