Tuning thermal conductivity of surface-initiated polymer brushes

Surface-initiated polymer brushes are widely used in industrial applications owing to their programmable interfacial properties and manipulation over the harmonious combination of materials at the molecular level, particularly in surface-coating technologies. So far, surface-initiated polymer brushes are emerging as robust candidates for heat dissipation coatings. However, the brushes of carbon nanotubes, nanowires, or polymers show a terrible reduction of thermal conductivity, although a single carbon nanotube can exhibit a high value of thermal conductivity. Thus, how to control the thermal conductivity of surface-initiated polymer brushes remains a challenge for producing heat dissipation materials. Here we demonstrate programmable control of thermal conductivity of polymer brushes by tuning the grafted density on the target surface and the persistence length of polymer chains, using coarse-grained molecular dynamics (CGMD) simulations based on experimental data. Our simulation results show that the thermal conductivity of surface-initiated polymer brushes is anisotropic and a delicate balance between the grafted density and persistence length. Moreover, detailed structure analysis and phonon analysis are conducted to unveil the thermal characteristics of polymer brushes. We expect that our results may help broaden the industrial applications of surface-initiated polymer brushes.