Facile Molecular Design Strategy for Poly(aryl ether ketone)s with Simultaneous Reductions in Dielectric Constant and Loss

The growing demand for high-speed communication and highly integrated electronic devices has emphasized the importance of low-dielectric insulator materials. Herein, we present a facile molecular design strategy for poly(aryl ether ketone)s that simultaneously reduces the dielectric constant (Dk) and loss (Df). The incorporation of bulky cyclohexane side groups increased the intrinsic free volume while limiting additional relaxation. Selective methyl substitution further modulated dielectric properties; methyl groups on cyclohexane groups increased the free volume, whereas those on aromatic rings restricted the chain mobility. Dispersion-corrected density functional theory single-point calculations revealed a high torsional barrier for aromatic methyl groups, consistent with the restricted rotational motion. Consequently, the resulting polymer exhibited low Dk and Df values (2.65 and 0.0021, respectively) at 28 GHz. These dielectric property improvements were achieved by preserving the mechanical and thermal stabilities of the films, indicating the effectiveness of precise molecular design for next-generation low-k polymers.