Facile Preparation of Mechanochromic Polyurethane Blends with Dual Dyes via a Ratio Luminescence Mechanism

Key words:  mechanochromic materials, ratio luminescence, blend, dyes, polyurethane

Abstract:

Mechanochromic materials exhibit changes in their optical properties when exposed to external forces, making them highly valuable for applications, such as mechanical sensing and component damage monitoring. Herein, a facile and low-cost method for preparing mechanochromic materials is developed based on the ratio luminescence mechanism. Rather than using sensors with complex structural dual chromophore groups, commercially available methyl orange and methylene blue, which exhibit minimal spectral overlap, are incorporated into thermoplastic polyurethane film at a fixed ratio. As the strain increases, the blending film exhibits a pronounced color change, transitioning from bright yellow-green to golden yellow. In the spectra, the ratios of both the absorption peaks and the emission peaks of the two dyes have changed. The doping of dyes leads to a reduction in both tensile strength and modulus. However, the material exhibits exceptional strain-induced color-changing performance and hydrophobic properties, which enhance its high applicability for marine engineering and aerospace technology. This approach is not only straightforward and cost-effective but also offers a novel pathway for the preparation of mechanochromic materials, showcasing significant potential for practical applications and broad future development prospects.