Effect of Polymer Grafting Density on Mechanophore Activation at Heterointerfaces.

Silica nanoparticles grafted with poly(methyl acrylate) chains whose anchor points are maleimide-anthracene cycloadducts were prepared at various grafting densities to demonstrate fundamental characteristics of mechanophore activation at heterointerfaces. The monotonically decreasing correlation between polymer grafting density and surface-bound maleimide-anthracene mechanophore activation was quantitatively elucidated and discussed. Presumably as a result of polymer-polymer interactions, polymer grafting density plays a significant role in heterogeneous mechanophore activation. The findings are a valuable guide in the design of efficient force-sensitive, damage-reporting polymer composites, where damage is often localized to the interface between the matrix and the reinforcing phase.