Shape Memory Polymers with Self-folding Deformation and Multi-stimulus Response

Shape Memory Polymers (SMPs) need to be given a temporary shape in advance to realize the shape memory process, but the manual shaping process is cumbersome and has low precision. Here, we propose a universal applicable method for 4D printing self-folding SMPs by pre-stretching extruded filaments during 3D printing, the temporary shape of the SMPs were designed and fixed during 3D printing. Prepared samples can automatically perform shape memory process under stimulation without manual temporary shape programming process. Furthermore, using carbon ink as a photothermal conversion agent enables the 4D printing SMPs to have thermal and light response characteristics. In addition, some bionic applications of self-folding SMPs were demonstrated, such as self-morphing grasper, DNA double helix structures, programmable sequential switching mimosa, self-folding box and human hand. The combination of SMP and 3D printing fully takes advantage of 4D printing technology, and the self-folding SMPs show great potential applications in the fields of tissue engineering scaffold, self-folding robots, self-assembly system and so on.