Topological Rearrangement-Induced\nMesoscale Phase\nRedistribution to Enhance the Fatigue Resistance of Polymer Blends

Maintaining a high modulus to simultaneously withstand\ndeformation\nand increase fatigue resistance to restrict crack propagation in a\nmaterial presents a significant challenge. In this work, a straightforward\nstrategy was developed to address this issue in polymers. A dynamic\nnetwork was incorporated into a permanent one prior to the formation\nof the latter, and two incompatible polymer networks were created\nto prevent common phase separation. The mechanical and fatigue resistance\nproperties were substantially enhanced by the exact modulation of\nthe soft and hard phase distribution by precise control over the densities\nof dynamic and permanent networks as well as the number of reprocessing\nsteps. The experimental results demonstrated a nearly 9-fold increase\nin the fatigue life of polyurethane compared with traditional design\nmethods and a 2.5 times increase in modulus. This strategy shows potential\nfor the design of fatigue-resistant thermosetting and thermoplastic\nmaterials. The results offer new insight into the development of durable,\nhigh-performance materials that are reprocessable and compatible.