EPPOSS-Toughened Cyanate Ester Adhesive Films With Low Dielectric Constant and Excellent High-Temperature Resistance

POSS-modified cyanate ester adhesives were widely employed in high-frequency communications and medical devices due to their excellent dielectric properties, mechanical properties, and heat resistance. However, for cyanate ester adhesive films, the film-forming ability, viscosity, and bond strength required were highly sensitive to the influence of nanomaterials. Herein, an epoxy-functionalized POSS (EPPOSS) was incorporated to enhance interfacial compatibility, leveraging its epoxy groups to ensure uniform dispersion and mitigate these issues. This strategy simultaneously improved adhesive films' toughness through nanoscale reinforcement. The resulting adhesive films with 5 wt% EPPOSS exhibited a superior room-temperature lap shear strength of 39 MPa, retained 55% (22 MPa) of this strength at 200°C. Furthermore, the dielectric constant of the adhesive film decreased from 3.5 to 3.1 at 1 MHz and dropped to 2.82 at 10 GHz frequencies. This work provides a facile and effective approach to fabricating high-performance cyanate ester adhesive films for demanding applications.