Self-Stratified Coating with Multiresponsive Self-Healing Polymer

Self-stratifying coating produces multicoat films by single-coat application, which offers superior performance by enhancing both the adhesion and surface properties simultaneously, suitable for many special coatings and industrial applications. Here, we have developed a well-defined multifunctional self-stratifying coating material with self-healing abilities from blending two copolymers based on fluorous/thiol/siloxane. Combinations of silyl copolymer (PMEA-co-PCMA-co-PTEPA) and fluorous copolymer (PMEA-co-PCMA-co-PHFA) offer spontaneous stratification into three layers with a gradient behavior. This transparent (>90% transmittance) coating provides a highly hydrophobic surface with good hardness (28 MPa). The polymer coating self-repairs under UV light with >80% efficiency. In addition, the healing is also conceivable by heating at 70 °C or by spraying amine due to the thiol-Michael reaction

Ultrasensitive and Highly Selective Electrochemical Detection of Dopamine Using Poly(ionic liquids)–Cobalt Polyoxometalate/CNT Composite

A novel sandwich polyoxometalate (POM) Na₁₂[WCo₃(H₂O)₂(CoW₉O₃₄)₂] and poly­(vinylimidazolium) cation [PVIM⁺] in combination with nitrogen-doped carbon nanotubes (NCNTs) was developed for a highly selective and ultrasensitive detection of dopamine. Conductively efficient heterogenization of Co₅POM catalyst by PVIM over NCNTs provides the synergy between PVIM–POM catalyst and NCNTs as a conductive support which enhances the electron transport at the electrode/electrolyte interface and eliminates the interference of ascorbic acid (AA) at physiological pH (7.4). The novel PVIM–Co₅POM/NCNT composite demonstrates a superior selectivity and sensitivity with a lowest detection limit of 500 pM (0.0005 μM) and a wide linear detection range of 0.0005–600 μM even in the presence of higher concentration of AA (500 μM)

Fluorous Membrane Ion-Selective Electrodes for Perfluorinated Surfactants: Trace-Level Detection and in Situ Monitoring of Adsorption

Ion-selective electrodes (ISEs) with fluorous anion-exchanger membranes for the potentiometric detection of perfluorooctanoate (PFO^–) and perfluorooctanesulfonate (PFOS^–) were developed. Use of an anion-exchanger membrane doped with the tetraalkylphosphonium derivative (R_f8(CH₂)₂)­(R_f6(CH₂)₂)₃­P⁺ and an optimized measurement protocol resulted in detection limits of 2.3 × 10^–9 M (1.0 ppb) for PFO^– and 8.6 × 10^–10 M (0.43 ppb) for PFOS^–. With their higher selectivity for PFO^– over OH^–, membranes containing the alternative anion exchanger (R_f6(CH₂)₃)₃­PN⁺P­((CH₂)₃­R_f6)₃ with a bis­(phosphoranylidene)­ammonium group further improved the detection limit for PFO^– to 1.7 × 10^–10 M (0.070 ppb). These values are comparable with results obtained using well-established techniques such as gas chromatography–mass spectrometry (GC–MS), liquid chromatography–mass spectrometry (LC–MS), and liquid chromatography–tandem mass spectrometry (LC–MS–MS), but the measurement with ISEs avoids lengthy sample preconcentration, can be performed in situ, and is less costly. Even when eventual spectrometric confirmation of analyte identity is required, prescreening of large numbers of samples or in situ monitoring with ISEs may be of substantial benefit. To demonstrate a real-life application of these electrodes, in situ measurements were performed of the adsorption of PFOS^– onto Ottawa sand, which is a standard sample often used in environmental sciences. The results obtained are consistent with those from an earlier LC–MS study, validating the usefulness of these sensors for environmental studies. Moreover, PFOS^– was successfully measured in a background of water from Carnegie Lake