Dielectric-mechanical couple effect of COF cyanate derived from dual functions of molecular interaction and chain entanglement

Abstract

The rapid advancement of radar and 5G communication technologies has created an urgent need for materials that possess both low dielectric constants and superior mechanical strength to ensure efficient signal transmission and minimal loss. Herein, a synergistic effect of multiple regulation strategies from the atomic scales to the molecular scales was proposed to develop Covalent Organic Frameworks (COFs) modified cyanate ester resins (COF-mCE). The strategy has proven highly effective in enhancing both dielectric and mechanical properties. With only 3 wt% COFs, the dielectric constant of COF-mCE is reduced from 3.32 to 2.84 at 1 MHz. Meanwhile, the mechanical performance of COF-mCE composites exhibits substantial improvements, with flexural strength increasing by 42.6% and tensile strength by 52.1% compared to pure mCE. The investigation explores that hydrogen bonding and π-π stacking interactions restrain the polarization feature and the mechanical property improvements of the COF-mCE derived from the entanglement effect of COF-polymer chains. Furthermore, the 3D-printed COF-mCE honeycomb structure demonstrates excellent electromagnetic wave transmittance and low reflectance, achieving a transmittance of 94.1% at 10 GHz with a 60° incidence angle. This multi-scale design strategy offers new insights into the development of low-k dielectric material for next-generation electronic science applications.