POS1-1345
Synthesis and Mechanochemistry of Poly(bicyclo[n.2.0]alkenes)
Topic
S1. Polymer Synthesis
When and Where
Sep 30, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Heesuk KIM
Jinhye BAE
Presenter(s)
Moritz Hansen (Stanford University)
Co-Author(s)
Abstract
Mechanochemical activation of polymers represents a powerful approach to trigger chemical transformations using mechanical force. Traditionally, repeat units containing highly strained motifs were required for successful mechano-activation. Herein, we present the synthesis, mechano-triggered cascade activation, and “rezipping” of poly(bicyclo[n.2.0]alkenes). By choosing different ring sizes (n), one can judiciously select a desired ring strain. A convenient and scalable synthesis of the required bicyclo[n.2.0]alkene monomers was developed based on ketene [2+2]-cycloaddition, followed by simple transformations. Upon ultrasonication in the presence of hydrogen-atom donors, all polymers underwent selective C-C bond cleavage between allylic carbons, generating allylic biradicals that propagate along the polymer backbone. This cascade activation transforms the 1,2-divinylcycloalkene units into an alternating structure with high activation yield. Depending on ring-size, some mechanically transformed polymers could be "rezipped" back to their original structure through radical-mediated cyclization with up to >95% efficiency. This work demonstrates a reversible mechanochemical system with polymers containing varying, but small ring strains, expanding the scope of mechanoresponsive materials and providing insights into radical-mediated polymer transformations under mechanical stress.
