Recent advances in 4D printing of fiber-reinforced polymer composites: A review and outlook

4D printing technology has garnered significant attention for its ability to reshape 3D printed structures under external stimuli over time. However, the 4D printing of pure polymers still confronts several challenges, including inadequate mechanical properties, low energy output, constrained application environments, and limited design freedom. The emergence of fiber-reinforced polymer composites 4D printing technology (FRPCs4DP) provides a promising solution to these issues. This review, for the first time, delves into recent advances within the nascent realm of FRPCs-4DP, highlighting the roles of fibers. These roles include enhancing mechanical performance, improving actuation capabilities, diversifying actuation methods, and generating heterogeneous materials. Furthermore, the review provides a comprehensive overview of material compositions, additive manufacturing techniques, and design strategies associated with FRPCs-4DP. Finally, the review outlines the key challenges and future trends in FRPCs-4DP toward practical applications.