Design and Application of a Photo‐Thermal Dual‐Curable Resin for Architected Microwave Absorbers in the X‐Band via DLP Printing

The performance of structural electromagnetic absorbers critically depends on the dielectric matrix, which demands low permittivity, low loss, high mechanical strength, and good processability. However, traditional high-performance dielectrics, typically formed by hot pressing, cannot be fabricated with complex architectures precisely. Photocurable 3D printing resins offer high precision but suffer from inadequate thermal stability, wave transparency, and structural reliability, limiting their practical use. In this work, a novel isocyanate-functionalized monomer was designed and synthesized to construct a photo-thermal curable low dielectric resin system. This resin enables rapid curing and shape fixation under UV irradiation, followed by secondary crosslinking during post-thermal treatment, resulting in a dense and stable 3D network. The cured resin maintains a low dielectric constant (ε' < 3.0) and low dielectric loss (tan δ < 0.01) in the X-band, while exhibiting notable enhanced thermal stability (Tg > 200°C) and mechanical performance (tensile strength > 80 MPa). A dielectric honeycomb scaffold was subsequently fabricated via 3D printing, into which graphene-CoFe₂O₄ powders were introduced, together with a conductive silver layer cured at the bottom. The resulting composite achieved a minimum reflection loss of -59.8 dB at a thickness of only 1.93 mm in the X-band.