Reversible covalent chemistry for property modification of conjugated materials

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The intrinsic properties of conjugated materials are well-suited for their use in a range of plastic electronic devices. Such materials are prepared by coupling aromatic building blocks with robust covalent bonds. Tuning the properties of conjugated materials to match the requirements of a given application requires the judicious selection of monomer building blocks. Once coupled, the properties are locked and they cannot be adjusted. Material degradation during standard device operation results in performance deterioration. The device must then be discarded, resulting in environmental waste. The overarching program goal is to increase the reusability of devices by rejuvenated the intrinsic properties of conjugated materials. This will have ecological rewards, by improving the recycling of devices and reducing electronic waste that is disposed in land fills. Towards this end, it is proposed to leverage the reversibility of dynamic covalent bonds for property tuning. By incorporating the reversible bond into aromatic precursors, conjugated materials with reversible properties will be possible. Reversible property tuning will be done by exchanging the components of conjugated materials. Attaching the conjugated materials to an electroactive surface via covalent bonds will lead to electrodes whose color, fluorescence, and redox chemistry can be modified by reversibly exchanging the components. Different reversible covalent bonds will be explored to develop robust electroactive layers whose properties can be indefinitely adjusted and rejuvenated by component exchange. A combined electrochemical-spectrometer setup will be used to simultaneously measure the change in electrochemistry, color, and fluorescence with component exchange. Property regeneration and materials recycling will be applied to electrochromic devices for improving both their lifetime and end-of-life recyclability. Ultimately, devices can be reused in a different application by rewriting their properties via component exchange, making plastic electronics truly recyclable. Reversible covalent bonds will also be implemented into conductive-stretchable surfaces to make them self-healing. Towards this goal, new monomers will be prepared for developing reparable conductive elastomers. Fatigue induced breaks in the rubber-like electrodes that form when they are repeatedly stretched and bent can be repaired. The developed monomers will also be applied to other substrates, especially those from sustainable and degradable feedstocks. This will lead to the "greening" of plastic electronics by extending their lifetime. Developing electrodes from renewable resources coupled with the self-healing and recyclable properties will reduce the environmental footprint of plastic electronics. Collectively, these properties will move plastic electronics closer towards being truly sustainable, recyclable, and degradable.