Creating Nanoknot‐Like Domains for Robust Artificial Spider Silk Toward High Twistocaloric Performance

ABSTRACT High‐efficiency refrigeration materials with long cycle lifetimes are essential for reducing energy consumption in conventional cooling systems. Twistocaloric cooling, which harnesses nonlinear torsional stress, offers a promising pathway to enhanced cooling efficiency. However, a general design strategy for polymer‐based twistocaloric materials that combine high efficiency and long cycle life remains elusive. Here, we report spider silk‐inspired polybiurea elastomer fibers that exhibit exceptional mechanical properties and twistocaloric cooling performance. The material's architecture features nanoknot‐like domains formed via multiple hydrogen bonds and π – π interactions in the hard segments, which knot together the soft segments to provide high mechanical stability and substantial entropy changes. The polybiurea fibers with nanoknot‐like domains achieved an extraordinary combination of breaking strength of 316.5 MPa and toughness of 523.4 MJ m −3 . This engineered deformable knotted structure enables a maximum cooling temperature drop of −17.1 K (by twisting and stretching), a maximum Carnot efficiency of 89.7%, and operational durability up to 120 000 mechanical fatigue life cycles. We further demonstrate two out‐of‐phase operated twistocaloric devices designed to recover input mechanical energy, thereby enhancing overall system efficiency. This work presents a robust materials strategy for advancing high‐performance polymeric refrigeration materials and systems.