On the role of polymer chains in transducing external mechanical forces to benzocyclobutene mechanophores

The role played by polyethylene-like oligomers in transducing external tensile forces to benzocyclobutene mechanophores is investigated computationally. It is demonstrated that the oligomer chains do indeed exert a notable influence on the force dependence of the activation energies of both conrotatory and disrotatory ring-opening processes of a cis 1,2-disubstituted benzocyclobutene. This opens the doorway to tuning the properties of mechanoresponsive materials not only by changing the properties of the mechanophore itself, but also by tailoring the force-transducing chain molecules attached to it. Furthermore, it is found that these chains even have a profound impact on the topology of the force-transformed potential energy surface in the vicinity of conrotatory transition states. Hitherto unexpected and most striking is the phenomenon that some of these conrotatory transition states are found to drive the system to disrotatory products.