A Cross-Linker-Based Poly(Ionic Liquid) for Sensitive Electrochemical Detection of 4-Nonylphenol

In this study, we report a cross-linker-based poly(ionic liquid) (PIL) for the sensitive detection of 4-nonylphenol (4-NP). PIL was poly(1,4-butanediyl-3,3′-bis-l-vinylimidazolium dibromide) (poly([V(2)C(4)(mim)(2)]Br(2))). Poly([V(2)C(4)(mim)(2)]Br(2)) was prepared via one-step free-radical polymerization. The poly([V(2)C(4)(mim)(2)]Br(2)) was characterized by infrared spectroscopy, Raman spectroscopy, thermal gravimetric analyzer and scanning electron microscope. The poly([V(2)C(4)(mim)(2)]Br(2)) was then drop-cast onto a glassy carbon electrode (GCE) to obtain poly([V(2)C(4)(mim)(2)]Br(2))/GCE. In comparison with a bare GCE, poly([V(2)C(4)(mim)(2)]Br(2))/GCE exhibited higher peak current responses for [Fe(CN)(6)](3−/4−), lower charge transfer resistance, and larger effective surface area. While comparing the peak current responses, we found the peak current response for 4-NP using poly([V(2)C(4)(mim)(2)]Br(2))/GCE to be 3.6 times higher than a traditional cross-linker ethylene glycol dimethacrylate (EGDMA) based poly(EGDMA) modified GCE. The peak current of poly([V(2)C(4)(mim)(2)]Br(2)) sensor was linear to 4-NP concentration from 0.05 to 5 μM. The detection limit of 4-NP was obtained as 0.01 μM (S/N = 3). The new PIL based electrochemical sensor also exhibited excellent selectivity, stability, and reusability. Furthermore, the poly([V(2)C(4)(mim)(2)]Br(2))/GCE demonstrated good 4-NP detection in environmental water samples.