Emissive mechanoresponsive hybrid Poly(urethane) – EVERYONE

Direct translation of mechanical force into an easy to read luminescent signal opens a new realm of possibilities in the field of mechanical stress sensing. To date, the development of such functional materials relies mostly on organic emissive mechanophores and has been hampered by photobleaching, by their lack of sensitivity, or by their tremendous synthetic costs. The overall objective of EVERYONE is to push ahead the concept of MRL materials by developing low-cost organic-inorganic hybrid functional copolyurethane (PU) embedding two non-mechanoresponsive complementary emitters containing elements identified by E.U. as non-critical raw materials: 3-Oxindole derivatives and octahedral Mo6 clusters. Such smart material will perform a fast, efficient and reversible emission colour switch, noticeable with naked eye, upon mechanical stress and UV-2A irradiation.
Mo6 clusters are phosphorescent in the red-NIR with high quantum yield, possess an excellent photostability and are highly sensitive to O2. 3-Oxindole derivatives emit in the blue-green area and can be easily functionalized to interact with Mo6 and be copolymerized. EVERYONE gathers 2 fundamental concepts in a single material: i) the phosphorescence emission quenching effect of O2 that produces singlet oxygen and acts as O2 scavenger, ii) the straightforward polymer O2 permeability variation of semi-crystalline polymers upon mechanical solicitation. Many factors need to be considered and will be studied: the concentration and ratio of embedded emitters, the type of targeted deformation (elastic vs plastic) that will condition the ratio between hard and soft segments in the polymer strands, its molecular weight and degree of cross-linking. EVERYONE is a multidisciplinary project organized in 5 workpackages spanning from molecular and macromolecular synthesis, theoretical investigation, photophysical and mechanical studies.