Single material 4D printing by pre-strained Shape Memory Polymer

Abstract

4D printing, a technology that makes 3D printed outputs move by themselves, is a 3D printing technology for smart materials. As 3D printing technology did before, 4D printing will also play a major role in achieving the ultimate goals of smart materials such as self-assembly, self-healing, and variable infrastructure by giving new degrees of freedom to existing material design methods. In this research, we have developed a new method to solve the one of the biggest challenges in 4D printing technology: applying pre-strain at the printing stage. This technique is a simple process of pulling out the shape memory polymer while printing it out. It solves the pre-strain-applying problem easily and cheaply. At the same time, it enables to manufacture the shapes that could not be created with previous 4D printing technology. Finally, we succeeded in controlling the degree of pre-strain by manipulating printing variables.