|Jin, M.; Stihl, M.; Giesa, R.; Neuber, C.; Schmidt, H.-W.: (AB)n segmented copolyetherimides for 4D printing, Macromolecular Materials and Engineering, 306(1), 2000473 (1-9) (2021) -- DOI: 10.1002/mame.202000473|
The fourth dimension in 4D printing comprises the ability of materials to recover their shape with time by utilizing 3D printing in combination with shape memory polymers. The focus of this work is on 3D printing of physically crosslinked thermoplastic polymers, which allow a reversible transformation of a temporary to its original shape by the external stimulus temperature, thus realize 4D printing. In this context, (AB)n segmented copolyetherimides consisting of perylene and poly(ethylene glycol) (PEG) segments were synthesized and characterized regarding their thermal and rheological properties in view of 3D printing. The perylene imide segments act as reversible physical crosslinks which disassemble at temperatures between 100 and 200 °C. The PEG segments exhibit a low melting temperature around 40 to 60 °C and are semi-crystalline at room temperature. The results show that this type of (AB)n segmented copolyetherimides combine reliable 3D printing performance, indicated by low warp deformation and excellent interlayer bonding. With a blend of two copolymers, we were able to realize 4D printing.