Preparation And Performances Of Chemosensing Membranes Based On Composite Superfine Fibers

In this thesis, three organic chemosensors NaPh-N₃, RhB-NH₂ and PPh-NHNH₂ were firstly synthesized and their structures were characterized using Nuclear Magnetic Resonance spectra?NMR? and Fourier Transform Infrared spectra?FT-IR?. Then the three organic compounds were incorporated into cellulose acetate dopes respectively and electrospun into composite membranes with superfine fibers using the simple electrospinning method. Scanning electron microscopy?SEM?, X-ray photoelectron spectroscopy?XPS? and FT-IR were used to characterize the prepared composite membranes. The optical sensing properties of the prepared membranes were also investigated by UV-visible spectra. The main contents are as follows:1. The organic chemosensor NaPh-N₃, which contains sulfonyl azide functional group for selective recognition of hydrogen sulfide, was synthesized using commercial 4-sulfonyl-1,8-anhydride naphthalene potassium salt as starting materials. Then it was incorporated into cellulose acetate dopes and electrospun into composite membranes with superfine fibers using the electrospinning method. The results from UV-visible spectra demonstrated that the prepared nanofibrous membranes can selectively recognize hydrogen sulfide. Moreover, the recognization can also be investigated by naked-eye. In the presence of hydrogen sulfide, a color changes from pall yellow to brown happened on the composite membranes.2. The organic chemosensor RhB-NH₂ was synthesized by the reaction of ethylene diamine and RhodamineB. In the presence of hydrogen sulfate, multi-hydrogen bonds can be formed between RhB-NH₂ and hydrogen sulfate. After the RhB-NH₂ was mixed into cellulose acetate dopes, the composite membranes were obtained by electrospinning the mixture. The results from UV-visible spectra demonstrated that the prepared membranes can selectively recognize hydrogen sulfate. In addition, the recognization can also be investigated by naked-eye. In the presence of hydrogen sulfate, a color changes from white to pink happened on the composite membranes.3. The organic chemosensor PPh-NHNH₂, which contains hydrazine functional group for selective recognition of formaldehyde, was synthesized using commercial 4-bromo-1,8-naphthalene anhydride as starting materials. Then it was mixed with cellulose acetate dopes and electrospun into composite membranes using the electrospinning method. The results from fluorescent spectra demonstrated that the prepared composite membranes can selectively recognize formaldehyde. Furthermore, the recognization can also be investigated by naked-eye under UV light. In the presence of formaldehyde, the largely enhanced yellow color of the composite membranes was observed under UV light.