Abstract

We compare the low-strain mechanical properties of bottlebrush elastomers (BBEs) synthesized via ring-opening metathesis polymerization and free-radical polymerization. By comparing experimentally measured elastic moduli to the predictions of an ideal, affine network model, we define a structural efficiency ratio that captures how polymerization chemistry affects the resulting network structure — for example, dilute polymerization conditions produce softer BBEs. We show that polymerization chemistry significantly changes this structural efficiency ratio, and therefore the mechanical properties, of BBEs built from identical side chains, giving polymer chemists an additional design parameter for tuning bottlebrush network properties.