Design of Fluorinated Poly(Ether‐Pyridine) Films for Impedimetric Detection of Heavy Metal Ions

ABSTRACT

A series of fluorinated poly(ether‐pyridine)s were synthesized via polycondensation of bis‐perfluoropyridine with either bisphenol A (BPA) or isosorbide, a bio‐sourced diol. The polymers were characterized using ¹H and ¹⁹F NMR spectroscopy, and their molecular weights were determined using GPC. Thermal properties were assessed using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The presence of isosorbide in polymer P2 increases the glass transition temperature and results in a lower molecular weight and a higher hydrophilicity. On the other hand, polymer P3, based on BPA, shows the best thermal stability, the highest molecular weight, and the most pronounced hydrophobic character. Electrochemical impedance spectroscopy (EIS) was used to evaluate the modified gold electrodes for the selective detection of metal ions. Among the four target ions (Ni²⁺, Cd²⁺, Pb²⁺, and Hg²⁺), defined by the European Water Framework Directive, Pb²⁺ was selectively detected on the hydrophilic polymer P2, while Cd²⁺ was selectively detected on the hydrophobic polymer P3. The achieved detection limits were 5 × 10⁻¹¹ M, corresponding to 10 ng/L for Pb²⁺ and 5.6 ng/L for Cd²⁺, respectively.