Porous Electrospun Fibers as Optical Sensor for Metal Ion

Electrospun fibers as Fe3+ optical sensor were prepared from poly(methyl methacrylate) (PMMA), poly(vinyl chloride-co-vinyl acetate-co-vinyl alcohol), pyrene, and poly(ethylene glycol) (PEG) as a water-soluble porogen. The effect of PEG content (0-40 wt.%) on fiber size and morphology was studied using scanning electron microscopy (SEM). Uniform and bead-free fibers were obtained from all PEG loadings. The average diameter of fibers without PEG was 2.79 mu m. Fiber size increased upon incorporation of PEG, except for fibers from 20% PEG. Attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analysis and thermogravimetric analysis confirmed a complete removal of PEG after 24 h of immersion in water. Porous structures were clearly observed for fibers from solutions with 30 and 40% PEG. Since fiber breakage was observed after water immersion in fibers from solution with 40% PEG, only porous fibers from solutions with 10, 20, and 30% PEG were tested toward Fe3+. Porous fibers from 30% PEG solution exhibited highest sensing performance with the ratio of fluorescence intensities before and after (F-0/F) immersion into 1.0 mM Fe3+ solution of 1.31. In addition, the porous fibers showed highly sensitive and selective responses toward Fe3+ over other selected metal ions, and showed a good reversibility after two cycles of quenching and regeneration.