Effects of pre-programmed 4D printing process parameters on the shape memory performance of polyurethane

Abstract

4D printing technology endows printed samples with self-driven performance that increasingly show strong application prospects. Polyurethane, as a typical shape memory polymer, is widely used in 4D printing. Current researches on 4D printed polyurethane materials are focused on investigating polyurethane composites or novel printing techniques to optimize the shape memory properties of the printed samples. In this study, the effects of pre-programmed 4D printing process parameters on the shape memory properties of polyurethane were systematically investigated. The higher printing speed, higher printing temperature, and lower fill rate result in faster response time of the biomimetic samples with thermal stimulation. Based on the programming of process parameters (e.g., printing temperature, printing speed and filling rate), the biomimetic flowers and hands were processed to achieve a controlled behavior of sequential deformation. It was successfully achieved that only one printing material could demonstrate the shape memory effects with a sequential response process. The adjustable sequential deformations further enlighten the application of 4D printing technology in specific engineering fields such as aerospace, biomedicine, robot and military engineering, where parts must undergo a sequence of deformations to serve practical requirements.