Enhanced Thermal Conductivity of All-Organic Aramid Nanofiber Films via Interfacial Coupling Reaction

It is still a great challenge to prepare intrinsically all-organic thermal conductive membrane with high in-plane and through-plane thermal conductivity. Herein, we designed an all-organic aramid nanofiber thin film with in-plane and through-plane thermal conductivity as high as 15.7 and 0.26 W/mK, respectively, through one step fluorination utilizing F2/N2. We proved that direct fluorination could induce the coupling reaction of benzene rings in neighboring aramid macromolecules to form numerous covalent cross-linking bonds among aramid nanofibers. Benefiting from the cross-linking behavior, interfacial thermal resistance between the nanofibers was suppressed to some extent, thereby leading to enhancement of in-plane and through-plane thermal conductivity by 78.8% and 271.7%, respectively, compared with the unmodified membranes. In addition, the thin films also possess high mechanical strength and electrical insulation, which promote its application potential in flexible electronic fields.