Novel optical oxygen sensing material: metalloporphyrin dispersed in fluorinated poly(aryl ether ketone) films

A series of new fluorine-containing poly(aryl ether ketone)s (8F-PEKEK(Ar); Ar: 2-2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane (6FBA), 2,2-bis(4-hydroxyphenyl)propane (BA), 2-(4-hydroxyphenyl)-2-(3-hydroxyphenyl)propane (3,4′-BA) or 9,9′-bis(4-hydroxyphenyl)fluorine (HF)) are synthesized and applied to the matrix of optical oxygen sensing using phosphorescence quenching of metalloporphyrins, platinum and palladium octaethylporphyrin, (PtOEP and PdOEP) by oxygen. The phosphorescence intensity of PtOEP and PdOEP in 8F-PEKEK(Ar) films decreased with increase of oxygen concentration. The ratio I0/I100 is used as a sensitivity of the sensing film, where I0 and I100 represent the detected phosphorescence intensities from a film exposed to 100% argon and 100% oxygen, respectively. For PtOEP in 8F-PEKEK(Ar) film, I0/I100 values are more than 20.0 and large Stern–Volmer constants more than 0.19%−1 are obtained compared with PtOEP in polystyrene film. For PdOEP in 8F-PEKEK(Ar) film, on the other hand, the large I0/I100 values more than 143 are obtained. However, the Stern–Volmer plots of PdOEP in 8F-PEKEK(Ar) films exhibit considerable linearity at lower oxygen concentration range between 0% and 20%. These results indicate that PtOEP and PdOEP films are useful optical oxygen sensor at the oxygen concentration range between 0% and 100% and between 0% and 20%, respectively. The response times of PtOEP and PdOEP dispersed in 8F-PEKEK(Ar) films are 5.6 and 3.0 s on going from argon to oxygen and 110.1 and 160.0 s from oxygen to argon, respectively.