Digital Light Processing 3D Printing of Triple Shape Memory Polymer for Sequential Shape Shifting

A photocurable triple shape memory polymer (TSMP) resin based on acrylic monomers and an ion–pair comonomer (IPC) has been formulated and successfully 3D printed with a digital light processing (DLP) printer. The ion-rich and ion-poor domains produced by polymerization-induced microphase separation (PIMS) generate two well-separated glass transition temperatures and an excellent triple shape memory effect in the material, which is systematically studied by dynamic mechanical analysis (DMA) and atomic force microscopy (AFM). With the TSMP resin, an intermediate shape can be set to distinguish and program different shape evolution pathways (SEPs). To visualize the sequential shape shifting, several 3D models are printed and transform through distinct pathways. A potential application of shape memory microfluidics is also demonstrated as a proof-of-concept.