An Electrochemical Impedance Spectroscopy/Neutron Reflectometry Study of Water Uptake in the Poly(3,4-Ethylenedioxythiophene):Poly(Styrene Sulfonate)/Polymethyl Methacrylate-Polydecyl Methacrylate Copolymer Solid-Contact Ion-Selective Electrode

Abstract

Further to previous work on the ion-selective electrode (ISE) comprising a poly(3,4-ethylenedioxythiophene:poly(styrene sulfonate) [PEDOT : PSS] solid-contact (SC) and a plasticised polyvinyl chloride (PVC) membrane that led to blurring of interference fringes in neutron reflectometry (NR) data, the lipophilic polymethyl methacrylate/polydecyl methacrylate (PMMA-PDMA) copolymer ISE membrane was used to provide high quality NR data that is relatively free of interfacial roughening and unequivocal information on the uptake of water in this important SC ISE. The outcomes revealed that the hydrophobic PMMA-PDMA membrane remains free of absorbed water, while the underlying the PEDOT : PSS SC absorbs water, swelling and changing its neutron scattering properties.