4D Printing of novel poly(ethylene-vinyl acetate) / poly(butyl methacrylate-co-isobutyl methacrylate) shape memory polymer blends

4D printing is a technology that combines additive manufacturing with shape memory polymers, aiming to enhance the functionality of 3D printed structures. Filaments made from thermoplastic polymers are commonly used in Fused Deposition Modeling (FDM), which is one of the most prevalent types of 3D printing. Here, novel heat-responsive shape memory polymer blends were produced from ethylene-vinyl acetate copolymer (EVA) and poly(butyl methacrylate-co-isobutyl metacrylate) polymers. The effect of blend composition on the morphological, thermal, mechanical, and shape memory properties was investigated. The blend (60E-40B) containing 60 % by weight EVA and 40 % by weight BMA-co-iBMA exhibited optimum shape memory performance with a shape fixing (Rf) of 94.1 % and a shape recovery (Rr) of 94.5 % at a shape transition temperature (Ttrans) of 55 degrees C. Filament for the 60E-40B blend was produced for FDM type 3D printers, and 4D parts for various applications were printed using this filament. These 4D printed parts, designed for robotic grippers, self-assemble rivets, movable cog-wheel teeth, surface traps, and finger splints, displayed shape recovery characteristics in both hot oven and hot water environments.