LAUSR

Abstract Fluorescent chemosensory filter membranes composed of electrospun (ES) nanofibers and exhibiting a high sensitivity for pH and mercury ions (Hg 2+ ) were prepared using poly(2-hydroxyethyl methacrylate -co-N -methylolacrylamide -co- rhodamine derivative) (poly(HEMA -co- NMA -co- RhBN2AM)) by employing a single-capillary spinneret. The HEMA and NMA moieties were designed to exhibit hydrophilic properties (absorption for Hg 2+ in water) and chemical cross-linking (maintaining fiber structure in water), respectively. The fluorescence emission of RhBN2AM was highly selective for pH and Hg 2+ . Different compositions of poly(HEMA -co- NMA -co- RhBN2AM) were synthesized through free-radical polymerization, and their properties were explored. ES nanofibers prepared from copolymers with an 83.9:10.6:5.5 HEMA:NMA:RhBN2AM ratio ( P3-1.0 ES nanofibers) exhibited an apparent color change from nonfluorescent to red fluorescent when detecting Hg 2+ , and high reversibility due to their capability of repetitive on–off switchable fluorescence emission upon the sequential addition of Hg 2+ and ethylenediaminetetraacetic acid (EDTA). The P3-1.0 ES nanofibrous membranes had a higher surface-to-volume ratio than those of corresponding thin films, which enhanced their performance, and exhibited a strong chelation capacity for Hg 2+ of 94.82%. The prepared ES nanofibrous membranes with on/off switching capacity can be reused and applied as direct observation sensors, exhibiting the potential for application in water purification sensing filters.