4D Printing of Shape Memory Polymers

The combination of shape memory polymers and 3D printing has led to a new technique termed 4D printing where objected are fabricated that exhibit stimuli-responsive, shape-changing behavior. In this talk we will present approaches to 3D print shape memory polymers through digital light processing (DLP) and fused filament fabrication (FFF). In the case of DLP a monomer formulation containing alkyl acrylates and an ion-pair comonomer is free radically polymerized. The reaction induced microphase separation into ionic and non-ionic domains produces an interpenetrating network structure with two different glass transition temperatures, allowing for multiple shape memory processing. In the FFF printing filaments are prepared from shape memory polymer blends of a thermoplastic elastomer and a crystalline small molecule or polymer. The flow and alignment of the polymer chains during filament fabrication and printing improve the resultant shape memory properties material compared to analogous compression molded articles.