Synthesis of VOC-sensing Dyes for Fabrication of Cotton-based Chromogenic Sensors

Three vapochromic dyes named DiMo, MoMe, DiMe with different substituents were synthesized and investigated on their color change properties after exposure to 32 organic solvents after dyeing on cotton fabrics. The cotton-based sensor exhibited strong sensing properties to polar solvents rather than non-polar solvents. Especially, N,N-dimethylformamide detection was the best showing a color difference of 12.8 for DiMo, 21.4 for MoMe, and 25.8 for DiMe under 300 ppm exposure. Even at as low concentration as 10 ppm of N,N-dimethylformamide, the color change values were reached 7.3, 10.6, and 13.6 within an hour. The maximum absorption wavelength of the cotton-based sensor was shifted from 580 to 560, 570 to 560, and 560 to 540 nm, respectively, by the N,N-dimethylformamide exposure. The sensing mechanism was considered to depend on solvatochromism, aggregational properties of the dyes and adsorption amount of volatile organic compounds on textile substrates on which the dyes were applied. Finally, the reusability of the cotton-based sensor was tested for 10 cycles. Graphical abstract: [Figure not available: see fulltext.]