Abstract
In this paper, we examine the influence of 10 nm diameter silica nanospheres on oxygen diffusion in films of two different amorphous polymers characterized by a low glass-transition temperature and a high oxygen permeability. The two polymers, poly(dimethylsiloxane) (PDMS) and poly(n-butylamino thionylphosphazene) (C4PATP), are useful matrixes for oxygen sensors based upon luminescence quenching. In these applications, the dye platinum octaethylporphine (PtOEP), with a long-lived excited state, is incorporated into the polymer, and the presence of oxygen is registered through a quenching of the dye luminescence. For some sensor applications, these linear polymers themselves are too soft and tacky. Silica as a filler improves the mechanical properties of the matrix but perturbs the measurement of oxygen diffusion and permeation. We show that PtOEP adsorbs to the silica particles in PDMS but remains in the polymer matrix in C4PATP. The quenching kinetics of dye fluorescence is complex in PDMS because of con...
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