Versatile Mechanochemical Reactions Via Tailored Force Transmission in Mechanophores

In polymer mechanochemistry, regulating the intrinsic mechanical reactivity of a mechanophore offers extensive opportunities in material science, enabling the development of hierarchical and multifunctional polymer-based materials. Recent advances have focused on innovating various types of mechanophores with inherent reactivity (e.g. regioselectivity and stereoselectivity). However, little attention has been given to modulating their reactivity by tailoring force transmission within mechanophores. Here, we introduce a novel approach through the implementation of a cyclic pulling geometry into an anthracene-maleimide (AM) mechanophore. This approach manipulates force transmission within the mechanophore and effectively regulates its reactivity from 0.0160 min^-1 to 0.00133 min^-1, achieving up to a 12-fold change. Mechanochemical coupling analysis indicates that the split force transmission along ring chains contributes to the significant difference in mechanochemical reactivity. By leveraging the distinct force transmission pathways within cyclic and linear AM mechanophores, we covalently integrate them with a spiropyran mechanophore to design tandem mechanophore systems for hierarchical mechanochemical activation. These findings highlight the efficacy and versatility of the cyclic pulling strategy in modulating mechanophore reactivity, providing valuable insights for the design of tunable multifunctional polymer-based materials.