Spatially Selective and Density-Controlled Activation of Interfacial Mechanophores
Mechanically sensitive molecules known as mechanophores have recently attracted much interest due to the need for mechanoresponsive materials. Maleimide–anthracene mechanophores located at the interface between poly(glycidyl methacrylate) (PGMA) polymer brushes and Si wafer surfaces were activated locally using atomic force microscopy (AFM) probes to deliver mechanical stimulation. Each individual maleimide–anthracene mechanophore exhibits binary behavior: undergoing a retro-[4 + 2] cycloaddition reaction under high load to form a surface-bound anthracene moiety and free PGMA or remaining unchanged if the load falls below the activation threshold. In the context of nanolithography, this behavior allows the high spatial selectivity required for the design and production of complex and hierarchical patterns with nanometer precision. The high spatial precision and control reported in this work brings us closer to molecular level programming of surface chemistry, with promising applications such as 3D nanoprinting, production of coatings, and composite materials that require nanopatterning or texture control as well as nanodevices and sensors for measuring mechanical stress and damage in situ.
Additional Information© 2019 American Chemical Society. Received: December 19, 2018; Published: February 12, 2019. We thank Dr. Jun Li at UIUC and Ms. Yunbo Zheng at UC Davis for helpful scientific discussions and Dr. Logan Swartz at UC Davis for technical assistance. This work was supported by the Gordon and Betty Moore Foundation, the National Science Foundation (DMR 13-07354 and CHE-1808829), and the Office of Naval Research (Grant No. 0014-12-1-0828). M.J.R. gratefully acknowledges the Arnold and Mabel Beckman Foundation for a Beckman Institute Postdoctoral Fellowship. Author Contributions: A.R.S. and J.S. contributed equally to this work. The authors declare no competing financial interest.
Supplemental Material - ja8b10257_si_001.pdf