Preparation Of Fluorescent Conjugated Polymer Fibrous Membranes For Rapid Recognition Of Aromatic Solvents And The Investigation Into The Binary System In Fibers

Environmental pollution comes together with the rapid economic development. Pollutant detection based on fluorescence gained more attention due to many advantages, such as easy operation, high sensitivity and low cost. In recent years, the huge demand for portable reusable sensing device makes more and more research focus on the development of solid fluorescence sensing materials. This study is to prepare fluorescent sensing fibrous membrane, for rapid recognition of aromatic solvents, aiming for facile and simple classification of the unlabeled solvents and organic waste in chemical lab and industry. Fluorescent poly(phenylenevinylene) (PPV)/poly(vinyl alcohol) (PVA) fibrous membrane was prepared via electrospinning of PPV precursor and PVA aqueous solution followed by thermal elimination. Further cross-linking produced the cross-linked membrane PPV/CPVA. Both PPV/PVA and PPV/CPVA membranes were found to have similar morphology and photophysics. These membranes showed a great fluorescence quenching response to aromatic solvents and a much smaller response to other organic solvents. Water also effectively quenched the fluorescence of PPV/PVA but not that of PPV/CPVA. This was attributed to un-cross-linked PVA being able to dissolve in water and the cross-linking improving the resistance of the membrane toward water. The sensing behavior was found to have good reversibility. Further investigation was carried out on the fibers as a binary blend. The contact angle study showed that addition of only about 1% of PPV into the matrix reduced the hydrophilicity of the membrane significantly, suggesting that the PPV chains would be located at the surface of the fibers. X-ray photoelectron spectroscopy (XPS) investigation further confirmed such surface enrichment of PPV in the binary polymer blends. The PPV chain on the surface facilitated the π-π interaction between the polymer backbones and the aromatic molecules, thus leading to good selectivity and fast response of the two fibrous membranes toward aromatic solvents.