Metallic nanoparticles exhibit high thermal conductivity ensuring significant improvement for polymers nanocomposites. Metallic nanoparticles such as silver nanowires (Ag NWs) improved the through-plane thermal conductivity of cigarette filters (CF, nonbiodegradable cellulose acetate), offering TC of 1.71 W•m -1 •K -1 at the loading of 2.8 vol% Ag NWs 115 . A cellulose nanofibers/MXene@Ag film showed TC of 22.43 W•m -1 •K -1 due to the synergistic effect of Ag NPs 116 .