Synthesis of an Acid-gas Sensing Fluorescence Dye Showing Change of Both Color and Fluorescence Emission Spectrum inside Polyethylenic Fiber on Exposure to Gas Phase Strong Acid for Application to Washable Textile Sensors

A halochromic fluorescence dye was synthesized to fabricate acid-gas sensing textiles. The dye has a maximum absorption at 436 nm and stokes shift of 54 nm in ethanol, which means that it exhibits a typical fluorescence color of greenish yellow. The dye was designed to have good substantivity toward hydrophobic and chemical resistant polyethylenic fibers, such as high molecular weight polyethylene (HMWPE) fibers, by introducing di-butyl and t-butyl groups on coumarin and benzoxazole moieties of the chromophore, respectively. The fluorescence dye showed the change of both color and fluorescence emission properties not only in a solution by addition of hydrochloric acid but also inside the HMWPE fiber on exposure to gas phase hydrogen chloride even at relatively low concentrations. From the repeat test, the sensing performance was maintained reversibly even after 20 repeat cycles of adsorption and desorption of gas phase hydrogen chloride. The HMWPE fabrics dyed with the fluorescence dye can be washable by showing fastness of rating 4–5 to washing.