In Honor of Nobel Laureate Prof. M Stanley Whittingham
| SIGNALING MECHANICAL FORCE IN SOLID-STATE POLYMERS WITH TRIARYLMETHANE MECHANOPHORES José Augusto Berrocal1; James R. Hemmer2; Christopher Rader3; Viola Bauernfeind2; 1INST. OF CHEMICAL RESEARCH OF CATALONIA, Tarragona, Spain; 2ADOLPHE MERKLE INSTITUTE, Fribourg, Switzerland; 3INSTITUTE OF CHEMICAL RESEARCH OF CATALONIA, Tarragona, Spain; PAPER: 103/Nanomaterials/Regular (Oral) OS SCHEDULED: 16:45/Wed. 29 Nov. 2023/Dreams 3 ABSTRACT: 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. References: [1] J. Li, C. Nagamani, J. S. Moore, Acc. Chem. Res. 2015, 48, 2181–2190. [2] Y. Chen, G. Mellot, D. Van Luijk, C. Creton, R. P. Sijbesma, Chem. Soc. Rev. 2021, 50, 4100–4140. [3] M. M. Caruso, D. A. Davis, Q. Shen, S. A. Odom, N. R. Sottos, S. R. White, J. S. Moore, Chem. Rev. 2009, 109, 5755–5798. [4] C. Calvino, L. Neumann, C. Weder, S. Schrettl, J. Polym. Sci. Part A Polym. Chem. 2017, 55, 640–652. [5] M. Abi Ghanem, A. Basu, R. Behrou, N. Boechler, A. J. Boydston, S. L. Craig, Y. Lin, B. E. Lynde, A. Nelson, H. Shen, et al., Nat. Rev. Mater. 2021, 6, 84–98. [6] J. R. Hemmer, C. Rader, B. D. Wilts, C. Weder, J. A. Berrocal, J. Am. Chem. Soc 2021, 143, 18859–18863. |
