High‐Density Polyethylenes with Dual Degradability Enabled by In‐Chain Photolyzable and Mechanoresponsive Units

Polyethylenes are the most widely produced plastics but are also major pollutants due to their exceptional chemical stability. Developing environmentally friendly alternatives that can simultaneously respond to multiple degradation triggers to replace conventional polyolefins is desirable. Herein, a novel class of high‐density polyethylene materials that degrade upon exposure to light irradiation and mechanical force is reported. This dual degradability is achieved by incorporating in‐chain photolyzable carbonyl and mechanoresponsive cyclobutane units via catalytic terpolymerization of ethylene, CO, and cyclobutene derivatives. Incorporating low densities of carbonyl and mechanoresponsive units has minimal impact on the thermomechanical properties of the polyethylene. Mechanical activation through ball‐milling triggers hydrolytic degradation via force‐induced cycloreversion of the cyclobutane units. This dual degradability can potentially reduce their environmental persistence in the environment.