The use of mechanical energy to increase reaction rates and alter the distribution of products has gained considerable interest of late. However, the discovery of new mechanophores (i.e., mechanochemically reactive units) is currently time-consuming, expensive, low-yielding, and a process that is not easily scaled to large quantities. Here we show that mechanophore-linked addition polymers are easily prepared using bifunctional initiators with a living radical polymerization method. The mechanophore is positioned close to the center of the polymer, where ultrasound-generated forces are the largest. Since these forces are strongly dependent on molecular weight, the use of controlled polymerization enables fine-tuning of the mechanical activity so that mechanophore reactions are initiated while minimizing chain scission. The approach is illustrated first with the synthesis and investigation of a 1,2-disubstituted benzocyclobutene mechanophore that is incorporated into the center of a polymethacrylate (PMA) ...