Switching Ionic Diode States with Proton Binding into Intrinsically Microporous Polyamine Films (PIM-EA-TB) Immersed in Ethanol

Intrinsically microporous polyamines (PIM-EA-TB) provide tertiary amine binding sites for protons and in this way allow switching/gating from a low ionic conductivity state to semipermeable anion conductivity through micropores. In ethanolic NaClO ₄ media ionic conductivity in PIM-EA-TB films (approx. 10 μm thick; deposited asymmetrically onto a 10 μm diameter microhole in 5 μm thick Teflon) is lowered by ion exclusion compared to conductivity observed in aqueous environments. However, in the presence of protons in ethanol PIM-EA-TB films are shown to switch from essentially insulating to anionic diode behaviour. Similar observations are reported for Cu ²⁺ but not for other types of cations such as Na ⁺, K ⁺, Mg ²⁺ (all as perchlorate salts). Binding constants are evaluated, and protonation is identified to cause gating for both H ⁺ and Cu ²⁺. Both chemical and electrochemical gating/switching is demonstrated by placing a platinum electrode close to the PIM-EA-TB film and applying positive or negative bias to locally generate acid/base.