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A Latent Mechanoacid for Time-Stamped Mechanochromism and Chemical Signaling in Polymeric Materials
- Source :
- Journal of the American Chemical Society. 142:99-103
- Publication Year :
- 2019
- Publisher :
- American Chemical Society (ACS), 2019.
-
Abstract
- Mechanically coupled proton transduction offers potential for stress-responsive polymeric materials whose properties can be switched via acid-triggered coloration, polymerization/cross-linking, or degradation. The utility of currently available mechanoacids, however, is limited by modest force-free stability or a scissile response that caps mechanoacid generation at one proton per strained polymer chain. Here, we report a new mechanoacid based on 2-methoxy-substituted gem-dichlorocyclopropane (MeO-gDCC). Pulsed ultrasonication leads to the mechanochemical ring opening of the MeO-gDCC and the subsequent elimination of either HCl or MeCl, with ∼0.58 equiv of HCl released per mechanophore activation and ∼67 protons per chain scission event. Single-molecule force spectroscopy reveals that the methoxy substituent lowers the force required for rapid (kopen ∼102 s-1) ring opening to ca. 900 pN, vs 1300 pN required for the parent gDCC. The utility of the mechanoacid is demonstrated in silicone elastomers, where its mechanical activation leads to a strain-triggered color change prior to fracture of the elastomer. The postactivation kinetics of coloration are used to demonstrate a new concept in mechanochromism, namely, a spectroscopic indicator of not only whether and where a mechanical event has occurred but when it occurred.
- Subjects :
- chemistry.chemical_classification
Proton
Kinetics
Substituent
Force spectroscopy
General Chemistry
Polymer
010402 general chemistry
Photochemistry
Elastomer
01 natural sciences
Biochemistry
Catalysis
0104 chemical sciences
chemistry.chemical_compound
Transduction (biophysics)
Colloid and Surface Chemistry
Polymerization
chemistry
Subjects
Details
- ISSN :
- 15205126 and 00027863
- Volume :
- 142
- Database :
- OpenAIRE
- Journal :
- Journal of the American Chemical Society
- Accession number :
- edsair.doi.dedup.....dceac49db39145c8b0da3f8beb5051c8