Mechanochemically Gated Reactions for Force-Adaptive Polymeric Systems
Abstract
Stimuli-responsive polymers are important for a wide range of applications from sensing and damage detection to materials with active feedback systems for self-healing. Polymers that respond to heat, light, and chemical triggers are well developed; however, the use of mechanical force as an external stimulus to drive productive chemical transformations in polymers is an emerging area of research. In polymer mechanochemistry, polymer chains transduce mechanical force to stress-sensitive molecules called mechanophores that can be designed to undergo a wide variety of chemical reactions. Typically, mechanophores are activated with force to directly elicit a functional response, such as a change in color or luminescence. In contrast to typical mechanochemical reactions, an alternative concept of mechanically gated reactivity is proposed that decouples the mechanical activation event from the functional response to overcome current limitations of mechanochemistry for stress sensing. The overarching goal of the proposed research is to advance the concept of mechanically gated reactions and identify chemistries that will enable access to innovative force-responsive materials. The proposal will focus on three specific aims in order to accomplish this objective: development of a modular chemical platform for mechanically regulated photoswitching of diarylethene molecules that provides independent tunability of mechanochemical reactivity and photochemistry; investigation of alternative photoswitching platforms to expand the scope of mechanically gated photoswitching transformations; and evaluation of mechanically gated reactivity to achieve chemomechanical amplification of a chemiluminescence response. Computational calculations will be performed to guide experimental design, which significantly accelerate and streamline the discovery of mechanophores by predicting the impact of structural features on the mechanochemical behavior of molecules. Polymers will be synthesized for mechanochemical activation experiments using ultrasonication and the reactions will be characterized using spectroscopic methods. Mechanical activation of mechanophores identified through this process will also be studied in solid polymers under tension and compression to achieve stimuli-responsive polymeric materials. The proposed research will provide new fundamental insight into structure-mechanochemical activity, advancing the understanding of mechanophore design principles and enabling the design and synthesis of polymers with complex stimuli-responsive behavior.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jul 27, 2023
- Source ID
- W911NF2310298
Entities
People
- Maxwell J. Robb
Organizations
- Army Contracting Command
- California Institute of Technology
- United States Army