Development of PFAS Responsive Electrolyte‐Gated Field‐Effect Transistors Using Conjugated Polymer‐Single‐Walled Carbon Nanotube Complexes

Conjugated polymers are effective dispersants of SWNTs which also impart their properties onto polymer‐SWNT complexes. By modifying the polymer sidechain, the properties of the complex can be fine‐tuned for targeted applications. Here, we introduced pillar[5]arenes containing pendant quaternary ammonium groups onto the polymer side chains using strain promoted azide‐alkyne cycloaddition (SPAAC). The polymer effectively dispersed SWNTs, generating a polymer‐SWNT dispersion in aqueous media. Analysis by 19 F‐NMR demonstrated that this polymer exhibits electrostatic interactions between carboxylate ions of perfluoroalkyl acids and the pendant ammonium ions. Semiconducting (sc‐) enriched polymer‐SWNT complexes were prepared and subsequently functionalized with the pillar[5]arene side chains. The resulting water‐processable polymer‐SWNT complexes were incorporated in electrolyte‐gated field‐effect transistor (EGFET) devices, which demonstrated strong ambipolar performance and rapid signal stabilization using DI water as the supporting electrolyte. The EGFETs were used as proof‐of‐concept sensors capable of detecting potassium perfluorooctanoate (PFOK) and perfluorooctanoic acid (PFOH), and differentiating them from octanoic acid as a control. This work demonstrates that preparation of functional sc‐enriched polymer‐SWNT complexes enables proof‐of‐concept sensing using EGFET devices as a model platform.