Engineering heterogeneous domains and interfaces in shape memory fibers for tunable responsive behaviors

Intelligent materials have rapidly evolved to enable sensing and responding to various external stimuli, opening exciting opportunities across various fields such as soft robotics, actuators, biomedical devices, and sensors. Among these materials, Shape Memory Polymers (SMPs) have gained prominence for their unique shape memory effects and deformable properties. However, achieving effective control over these responsive behaviors remains a scientific challenge. To address this challenge, we present a novel strategy that involves creating heterogeneous domains and finely controlling interfaces within a single SMP material. Our approach leverages grayscale lithography-enabled printing, which facilitates the regulation of transition interfaces and orientations between relatively stiff and elastic domains within a fiber-shaped actuator. These deliberately designed heterogeneities give rise to tunable thermal stimuli-responsive behaviors and torsional mechanical energy. Our strategy, characterized by the manipulation of heterogeneous domains and their transition interfaces, opens a pioneering avenue for designing and fabricating intelligent materials and associated actuation devices.