Force-Induced Near-Infrared Chromism of Mechanophore-Linked Polymers
Qingkai Qi, Gaganjot Sekhon, Richard Chandradat, Nnamdi Ofodum, Tianruo Shen, Jan Scrimgeour, Monu Joy, Mario Wriedt, Madhuri Jayathirtha, Costel C. Darie, Devon A. Shipp, Xiaogang Liu, Xiaocun Lu
Abstract
A near-infrared (NIR) mechanophore was developed and incorporated into a poly(methyl acrylate) chain to showcase the first force-induced NIR chromism in polymeric materials. This mechanophore, based on benzo[1,3]oxazine (OX) fused with a heptamethine cyanine moiety, exhibited NIR mechanochromism in solution, thin-film, and bulk states. The mechanochemical activity was validated using UV-vis-NIR absorption/fluorescence spectroscopies, gel permeation chromatography (GPC), NMR, and DFT simulations. Our work demonstrates that NIR mechanochromic polymers have considerable potential in mechanical force sensing, damage detection, bioimaging, and biomechanics.