Simultaneous 4D printing and In-Situ foaming for tailoring shape memory behaviors in polylactic acid foams

This study introduces an innovative 4D printing technique combined with in-situ foaming to enhance the shape memory properties of polylactic acid (PLA) foams. By melt mixing PLA with azodicarbonamide (AZO) below its decomposition temperature, followed by direct pellet printing, the research achieves uniform microporous structures and tailored shape memory behaviors. The findings demonstrate that higher AZO content improves shape fixity (∼96 %) but reduces shape recovery. Moreover, the programming temperature significantly influences performance, with hot programming enhancing shape fixity and cold programming boosting shape recovery. This novel approach offers potential applications in lightweight, thermally insulative, and shock-absorbing materials with programmable properties.