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and bulk moduli from less than 0.1 to 100 GPa. Surprisingly, we discover that high thermal conductivity can arise not only in stiff frameworks but also in mechanically flexible COFs through directional alignment and anisotropy. Flexible COFs with carbon-carbon or carbon-nitrogen linkages, moderate-to-high densities, and low or intermediate void fractions exhibit ultrahigh thermal conductivities with phonon mean free paths that can extend up to several hundred nanometers when polymeric chains are well-aligned along the transport direction. These findings overturn conventional assumptions linking stiffness to thermal transport and demonstrate that structure-property relationships in COFs are highly tunable via chemical composition and topology. By establishing predictive design rules for achieving multifunctionality in porous polymers, this study provides a valuable roadmap for developing next-generation COFs with tailored thermal and mechanical performance.
Thakur et al. (Tue,) studied this question.