Preparation and properties of polydiacetylene based temperature sensors

Polydiacetylene vesicles with different concentrations were prepared, which have a good temperature-induced discoloration effect. As the temperature rises, the appearance colors appear blue-violet, purple, rose-red, watermelon-red and orange-red. The UV-Vis spectrophotometer was used to study the thermochromism process of the corresponding polydiacetylene molecules. As the temperature increased, the maximum absorption peak at 650 nm gradually decreased, the maximum absorption peak at 550 nm gradually increased, consistent with the appearance of color change. In addition, the blue-phase polydiacetylene molecule is not fluorescent, while the orange-red polydiacetylene molecule is fluorescent, and the fluorescence emission peak is at 560 nm. Fourier transform infrared spectroscopy was used to investigate the temperature-induced discoloration properties of polydiacetylene molecules. The possible reason was that with the increase of temperature, the perturbation of polydiacetylene molecules caused the distortion of the side chain structure, resulting the conformation transition of ene-yne conjugates. As the bone structure changes, the effective conjugation length becomes shorter, which in turn changes the color of the polydiacetylene molecule.