Mechanically Initiated Bulk-Scale Free-Radical Polymerization.

Mechanical initiation of polymerization offers the chance to generate polymers in new environments using an energy source with unique capabilities. Recently, a renewed interest in mechanically controlled polymerization has yielded many techniques for controlled radical polymerization by ultrasound. However, other types of polymerizations induced by mechanical activation are rare, especially for generating high-molecular-weight polymers. Herein is an example of using piezoelectric ZnO nanoparticles to generate free-radical species that initiate chain-growth polymerization and polymer crosslinking. The fast generation of high amounts of reactive radicals enable the formation of polymer/gel by ultrasound activation. This chemistry can be used to harness mechanical energy for constructive purposes in polymeric materials and for controlled polymerizations for bulk-scale reactions.