Improving Mechanoluminescent Sensitivity of 1,2-Dioxetane-Containing Thermoplastic Polyurethanes by Controlling Energy Transfer across Polymer Chains

1,2-Dioxetane was found as a mechanoluminescent probe when it was covalently linked into a polymer backbone. To bring about a further leap in sensitivity without sacrificing thermal stability of this mechanophore is highly desirable while a great challenge. Herein, we presented a new strategy to improve the mechanoluminescent sensitivity of 1,2-dioxetane-containing polyurethanes (PUs) by incorporating fluorescent dyes as the repeating units into the main chains of PUs. This approach provides simplified procedures to obtain mechanoluminescent films with high quality and increased amount of acceptor units. Compared to the same mechanophore-containing polymer with physically incorporated fluorophores, the two kinds of PUs not only exhibited enhanced light intensity and tunable emission colors but also displayed much lower force threshold upon deformation due to the efficient energy transfer. By virtue of these advantages, the current work will promise an invaluable tool to study failure mechanisms of thermoplastic elastomers at molecular level with unprecedented resolution.