4D Printing: Technological and Manufacturing Renaissance

Shape-memory materials (SMMs) combined with 3D printing to develop dynamic and adaptive products which are responsive to physical, chemical, or biological stimuli. These structures are categorized into 4D-printed (4DPed) products which change their shape and properties over time dimension. 4D printing, a novel, multidisciplinary, and futuristic technology is expanding its utilization in different applications including healthcare, space, textile, soft robotics, defence, sports, aerospace, and automotive sectors. This review article focuses on the recent and insightful developments in the 4DP technology of SMMs especially shape-memory polymers. This review also integrates printing technologies, the programming of materials for specific actuating mechanisms, and the most recent applications of 4DPed structures/products. Future perspectives and countless opportunities of this 4DP technology are outlined to address the current challenges which will help evolve and promote this novel technology as the mainstream manufacturing approach for developing real-world products in a myriad of engineering sectors. 4DP technology progresses beyond imagination, since its inception and will promote technological and manufacturing renaissance in the material science field. This technology will profoundly impact manufacturing and daily human life in the future.