Photopolymerization of Plasticizer in Ion-Sensitive Membranes on Solid-State Sensors

Article abstract of DOI:10.1021/ac00178a012

Poyl(vinyl chloride) membranes containing the K⁺ ionophore valinomycin and plasticized with dihexenyl adipate (DHA) can be photopolymerized in the presence of a radical initiator.Photolysis times of 30 min result in ca. 1.5percent reaction of DHA in the presence of O₂ and 8percent reaction in its absence, while 90 min is required for 7percent reaction with O₂ present.Photolysis for 30 min in air results in a 3- to 5-fold increase in lifetime for membranes coated on solid-state Si sensors, despite the low extent reaction of DHA.The slope of 57.5 mV, and selectivity coefficient for K⁺ over Na⁺ of 8 X 10^-5, are similar to dioctyl adipate plasiticized K⁺ membranes.Photolysis for 30min in the absence of O₂ results in 3-fold increase in lifetime of membrane-coated Si sensors, but the success rate of electrode preparation is only 50percent.The probability that polymerization and interfacially induced stresses are a factor in membrane degradation is discussed, as is the relevance to ion-sensitive field effect transistors.