Recent Advances in the Additive Manufacturing of Stimuli-Responsive Soft Polymers

Abstract

Stimuli-responsive polymers (SRPs) are special types of soft materials, which have been extensively used for developing flexible actuators, soft robots, wearable devices, sensors, self-expanding structures, and biomedical devices, thanks to their ability to change their shapes and functional properties in response to external stimuli including light, humidity, heat, pH, electric field, solvent, and magnetic field or combinations of two or more of these stimuli. In recent years, additive manufacturing (AM) aka 3D printing technology of these SRPs, also known as 4D printing, has gained phenomenal attention in different engineering fields, thanks to its unique ability to develop complex, personalized, and innovative structures, which undergo twisting, elongating, swelling, rolling, shrinking, bending, spiraling, and other complex morphological transformations. Herein, an effort has been made to provide insightful information about the AM techniques, type of SRPs, and their applications including, but not limited to tissue engineering, soft robots, bionics, actuators, sensors, construction, and smart textiles. This article also incorporates the current challenges and prospects, hoping to provide an insightful basis for the utilization of this technology in different engineering fields. It is expected that the amalgamation of 3D printing with SRPs would provide unparalleled advantages in different engineering arenas.