Periodic Reporting for period 1 - ReHuse (Reversible Heterolytic Mechanophores for Dynamic Bulk Materials)
Berichtszeitraum: 2023-08-01 bis 2026-01-31
Smart materials that respond to external stimuli have opened new opportunities for science and technology. So far, most responsive polymers rely on heat, light, or chemical inputs to change their properties. While these triggers are convenient, they often come with drawbacks, such as limited applicability or poor scalability. In contrast, living systems frequently use mechanical forces to regulate their functions—our sense of touch being a familiar example. However, translating this principle into artificial materials has proven to be a major challenge.
ReHuse—Reversible Heterolytic Mechanophores for Dynamic Bulk Materials seeks to address this gap by using mechanical force itself as a clean and efficient trigger. The project focuses on designing a new class of molecules, called reversible heterolytic mechanophores, that act as switches. Under stress, these molecules split into two oppositely charged fragments; once the stress is released, the fragments recombine. Unlike most mechanophore systems—which typically break irreversibly—these switches can be repeatedly turned “on” and “off,” opening the door to dynamic and sustainable polymer materials.
ReHuses’s objectives are twofold:
1. Fundamental understanding. We aim to uncover the design principles needed to create reversible heterolytic mechanophores.
2. Leverage fundamental knowledge for applications with bulk materials. We aim to integrate the reversible heterolytic mechanophores into polymers to access materials with dynamic functions. For instance, reversible bond splitting could facilitate the mechanical recycling of plastics, while reversible force-induced charge generation could allow polymers to shift between water-attracting and water-repelling states, creating the foundation for new technologies such as mechanically driven atmospheric water harvesting.
Overall, ReHuse is expected to deliver both fundamental and applied benefits:
• Advance knowledge in polymer mechanochemistry by demonstrating new, reversible mechanochemical activation modes.
• Contribute to sustainability goals by supporting better recycling strategies for plastics.
• Open pathways to address global challenges such as water scarcity through innovative materials for clean water production.
ReHuse—Reversible Heterolytic Mechanophores for Dynamic Bulk Materials seeks to address this gap by using mechanical force itself as a clean and efficient trigger. The project focuses on designing a new class of molecules, called reversible heterolytic mechanophores, that act as switches. Under stress, these molecules split into two oppositely charged fragments; once the stress is released, the fragments recombine. Unlike most mechanophore systems—which typically break irreversibly—these switches can be repeatedly turned “on” and “off,” opening the door to dynamic and sustainable polymer materials.
ReHuses’s objectives are twofold:
1. Fundamental understanding. We aim to uncover the design principles needed to create reversible heterolytic mechanophores.
2. Leverage fundamental knowledge for applications with bulk materials. We aim to integrate the reversible heterolytic mechanophores into polymers to access materials with dynamic functions. For instance, reversible bond splitting could facilitate the mechanical recycling of plastics, while reversible force-induced charge generation could allow polymers to shift between water-attracting and water-repelling states, creating the foundation for new technologies such as mechanically driven atmospheric water harvesting.
Overall, ReHuse is expected to deliver both fundamental and applied benefits:
• Advance knowledge in polymer mechanochemistry by demonstrating new, reversible mechanochemical activation modes.
• Contribute to sustainability goals by supporting better recycling strategies for plastics.
• Open pathways to address global challenges such as water scarcity through innovative materials for clean water production.
In the first two years of ReHuse, we have made substantial progress toward establishing the foundations of heterolytic mechanophores. Our research has focused on three main fronts:
• Design and validation of new mechanophores: We have created and computationally screened families of triarylmethane and diarylmethane derivatives, evaluating substituent effects and exploring both direct bond-stretching and flex-activation mechanisms. These insights are being distilled into design rules that will guide future synthesis.
• Integration into polymer matrices: We developed protocols to incorporate mechanophores into polyacrylates and are now extending this chemistry to polyurethane elastomers. This enables the transition from small-molecule concepts to bulk materials suitable for mechanical testing and application.
• Demonstration and characterization: Dedicated experimental setups and analytical frameworks now allow us to monitor mechanophore activation inside polymer networks. Three manuscripts based on these findings have been submitted, and a semi-empirical method to generalize design guidelines is under development.
In parallel, the ERC support has catalyzed two complementary research lines. First, we have been exploring concepts related to dynamic covalent polymers based on structural motifs derived from the 1,3-diketone scaffold and published a major review in Chemical Reviews. These materials are central to creating plastics that are more recyclable and adaptive. Second, in collaboration with Prof. Di Stefano (University of Rome “La Sapienza”), we initiated work on dissipative supramolecular polymerizations, yielding a first publication in the Journal of the American Chemical Society. This last line is not directly tied to ReHuse, but it broadens our expertise in energy-driven, life-like material systems.
• Design and validation of new mechanophores: We have created and computationally screened families of triarylmethane and diarylmethane derivatives, evaluating substituent effects and exploring both direct bond-stretching and flex-activation mechanisms. These insights are being distilled into design rules that will guide future synthesis.
• Integration into polymer matrices: We developed protocols to incorporate mechanophores into polyacrylates and are now extending this chemistry to polyurethane elastomers. This enables the transition from small-molecule concepts to bulk materials suitable for mechanical testing and application.
• Demonstration and characterization: Dedicated experimental setups and analytical frameworks now allow us to monitor mechanophore activation inside polymer networks. Three manuscripts based on these findings have been submitted, and a semi-empirical method to generalize design guidelines is under development.
In parallel, the ERC support has catalyzed two complementary research lines. First, we have been exploring concepts related to dynamic covalent polymers based on structural motifs derived from the 1,3-diketone scaffold and published a major review in Chemical Reviews. These materials are central to creating plastics that are more recyclable and adaptive. Second, in collaboration with Prof. Di Stefano (University of Rome “La Sapienza”), we initiated work on dissipative supramolecular polymerizations, yielding a first publication in the Journal of the American Chemical Society. This last line is not directly tied to ReHuse, but it broadens our expertise in energy-driven, life-like material systems.
With respect to the central focus of ReHuse—reversible heterolytic mechanophores—the work is still in the early stages of developing and validating design principles, and no results have been published yet. Nevertheless, three manuscripts have recently been submitted, and the key findings are expected to be disseminated in the upcoming 4–6 months. These results will establish the first experimentally validated guidelines for designing (reversible) heterolytic mechanophores, which is essential for enabling their use in functional materials. Considering the little attention and practical demonstrations of force-induced heterolytic bond cleavage reported in the literature, all results obtained thus far in the project should be considered beyond the state of the art in the field of polymer mechanochemistry.
The potential impact of these outcomes remains significant on many levels:
• Scientific: ReHuse can provide the field with a new mechanochemical paradigm based on reversible, heterolytic bond activation.
• Technological: ReHuse can open opportunities for recyclable plastics and mechanically driven control of material properties.
• Societal: ReHuse can contribute to more sustainable material cycles and energy-efficient responsive systems.
Thus far, ReHuse has globally delivered: (1) candidate (reversible) mechanophores with validated designs, (2) their incorporation into bulk polymers, (3) experimental setups for activation studies, and (4) high-impact publications and collaborations that expand the project’s scope. These achievements lay the groundwork for the second project phase, where we will continue the investigation on reversible mechanophores and eventually/possibly deploy them in functional, dynamic materials.
The potential impact of these outcomes remains significant on many levels:
• Scientific: ReHuse can provide the field with a new mechanochemical paradigm based on reversible, heterolytic bond activation.
• Technological: ReHuse can open opportunities for recyclable plastics and mechanically driven control of material properties.
• Societal: ReHuse can contribute to more sustainable material cycles and energy-efficient responsive systems.
Thus far, ReHuse has globally delivered: (1) candidate (reversible) mechanophores with validated designs, (2) their incorporation into bulk polymers, (3) experimental setups for activation studies, and (4) high-impact publications and collaborations that expand the project’s scope. These achievements lay the groundwork for the second project phase, where we will continue the investigation on reversible mechanophores and eventually/possibly deploy them in functional, dynamic materials.