High Through-Thickness Thermal Conductivity in an Edge-On Two-Dimensional Polyamide Thin Film

High thermal conductivity is essential for polymer applications such as electronic chip encapsulation, where efficient heat dissipation ensures system functionality and reliability. Here, we introduce a novel strategy to enhance through-plane thermal conductivity in 2D covalent organic frameworks (COFs). A highly crystalline edge-on 2D polyamide (v2DPA) film achieves a thermal conductivity of 1.16 ± 0.05 W/(mK) at 310 K, surpassing the previous record (1.03 W/(mK) in COF-5 [Evans et al. <i>Nat. Mater.</i> 2021, 20, 1142]) and aligning with molecular dynamics predictions (1.11 ± 0.07 W/(mK)). This value is nearly three times higher than that of bulk PA (0.34 ± 0.03 W/(mK)). Phonon dispersion calculations attribute this enhancement to strong covalent bonding, increasing phonon lifetimes, and group velocities. Our findings highlight the effectiveness of orienting 2D polymer and layer-stacked 2D COF films in an edge-on configuration to improve through-thickness thermal conductivity, offering a promising pathway for their integration into electronic thermal management applications.