Regulating Heterogeneous Catalysis of Gold Nanoparticles with Polymer Mechanochemistry.

Polymer mechanochemistry has emerged as a unique approach to regulate homogeneous catalysis in chemical transformations. The utilization of polymer mechanochemistry to regulate heterogeneous catalysis, however, still remains to be investigated. In this study, using polymer-grafted gold nanoparticles as the model heterogeneous catalysts, we show that polymer chains can be mechanically ruptured from the surface of gold nanoparticles, and thus, the catalytic activity of gold nanoparticles can be accelerated under sonication. The mechanical activation of polymer-grafted gold nanoparticles only occurs when the grafted polymer chains exceed a threshold molecular weight. This mechanical behavior is similar to those mechanophore-linked polymers. More importantly, further characterizations reveal that the Au-Au bonds instead of the Au-S bonds are broken at the heterointerfaces of polymer chains and gold nanoparticles. Our study unveils an unprecedented characteristic of polymer-grafted metallic nanoparticles in response to external mechanical stress.