4d Printing Light Drive Shape Morphing Double-Layer Structure

Shape-memory polymers (SMPs) with complex deformation patterns have great potential for biomedical, smart robotics, and electronic devices applications. However, after fabrication, the non-tunable and single permanent shape limits the development of SMPs. Here, we obtained a bilayer structure by depositing SMP on a taut pre-strain layer using 4D printing, which produces complex bidirectional spatial 3D shape transformation under the combined effect of the pre-strain layer and 3D printing layer. In addition, the effects of 3D printed layer thickness, aspect ratio, filling angle, filling rate, elongation of pre-strained layer, and deflection angle of pre-strained layer stretching direction and 3D printing long axis direction on the deformation of bilayer structure were investigated. The results show that by adjusting the above factors, the initial upward bending curvature of bilayer structure, reverse downward deformation mode, and degree of bilayer structure under IR action were programmable. Thus, the adjustment of the permanent shape of the bilayer structure was achieved by using the above strategies. Meanwhile, with the presence of 3D printed layer SMP, the bilayer structure also has shape memory properties for complex shape memory. Therefore, this study further enriches the deformation modes of 4D printed SMPs to provide more complex and controllable permanent shape deformation.