Oxygen Diffusion in Polymer Films for Luminescence Barometry Applications

Abstract

This chapter reviews recent results on the measurement of oxygen diffusion and oxygen perme-ability in thin polymer film coatings by luminescence quenching experiments. These coatings have the potential to serve as "pressure-sensitive paints" for luminescence barometry applica-tions. We compare results of steady-state measurements with those of pulsed-laser experiments for polydimethylsiloxane (PDMS), a series of commercial silicone resins, and several poly (thionyl-phosphazene) homopolymers (CnPATP) and copolymers. In some systems we com-pare the quenching properties of two different dyes and conclude that the efficiency of quenching by oxygen of platinum octaethylporphine triplets has twice the efficiency as quenching the excit-ed state of tris(diphenylphenanthroline) ruthenium dichloride. Our major interest is the rela-tionship between the polymer structure and oxygen permeation and diffusion in the polymer. When the polymer is crystalline, as in the case of poly(tetramethylene oxide) (PTHF), these pro-perties evolve as the polymer undergoes slow crystallization. In PATP-PTHF block copolymers, microphase separation introduces another level of complexity, since the dye is likely partitioned into both microphases. The block copolymers have the very attractive feature that they exhibit the high permeability of PATP itself, without the surface tackiness of the homopolymer.