UV-assisted direct ink writing 4D printing of benzoxazine/ epoxy thermosets

Benzoxazine is employed in an increasing number of domains due to its exceptional thermal stability, but it is difficult to apply for 4D printing due to its high brittleness and lack of photo-curable groups. Herein, dual-cure DIW 4D printing inks (BZs) consisting mainly of a commercial benzoxazine and a synthesized diglycidyl ether bisphenol A monoacrylate (DGEBAMA) were formed. In the dual-cure ink, photo-curable groups were cross-linked to rapidly prototype complex structures. After thermal curing, 4D-printing structures with isotropic properties were obtained. The ether bonds provided by the copolymerization of epoxy groups and oxazine rings and the soft segment of DGEBAMA increased the material's toughness. The highest overall performance was obtained by BZ50, which displayed higher glass transition temperature (188 degrees C), tensile strength (92.13 MPa), elongation at break (9.34 %), and good shape-memory ability. This work provides a straightforward method for enabling the 4D printing of benzoxazine/epoxy-based materials with good toughness, excellent thermal properties, and shape-memory abilities, expanding the potential application of benzoxazine/epoxy-based materials in advanced fields.