Editors: | F. Kongoli, M.P. Brzezinska, M.A. Alario-Franco, F. Marquis, M.S. Noufal, E.Palomares, J.M. Poblet, D.M. Guldi, A.A. Popov, A.R. Puente Santiago, B. Raveau, D. G. Rodriguez, S. Stevenson, T. Torres, A. Tressaud, M. de Campos |
Publisher: | Flogen Star OUTREACH |
Publication Year: | 2023 |
Pages: | 166 pages |
ISBN: | 978-1-989820-78-0 (CD) |
ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
Polymer mechanochemistry studies the interaction between mechanical force and polymer materials, in both fluid- and solid-state systems, through the development of so-called mechanophores.[1][2] The latter are chemical motifs that generate physicochemical signals in response to the cleavage of weak bonds, which may be covalent or supramolecular.[2] Some mechanophores exhibit the particularly attractive feature of being mechanochromic, meaning that they change their optical properties (absorption or emission of light) as a consequence of the force-triggered bond cleavage event.[3][4] This has paved the way for their use as force sensors to predict/anticipate the end-of-life or mechanical failure of polymer materials.[5]
This contribution will address covalent, heterolytic mechanophores, i.e., motifs that dissociate into ion pairs upon mechanical stimulation. This force-triggered bond cleavage mechanism has primarily been reported in solutions but is not often encountered in solid-state systems. Our group has recently provided the first example of a heterolytic mechanophore that can be mechanically activated in solid-state materials leveraging appropriately designed triarylmethane scaffolds (Tr). By performing uniaxial deformation experiments in conjunction with optical techniques in a home-built setup, we will show that the initially colorless Tr species dissociate into brightly colored, resonance-stabilized triarylcarbenium ions (Tr+)and anionic counterparts.[6] Additionally, the strong mechanochromic response can be easily tuned via simple structural modifications. The fundamental and applicative implications of our findings will be further discussed.