Transparent, High-Thermal-Conductivity Ultradrawn Polyethylene/Graphene Nanocomposite Films

Transparent, ultradrawn, ultrahigh molecular weight polyethylene (UHMWPE)/graphene nanocomposite films with a high thermal conductivity are successfully fabricated by solution-casting and solid-state drawing. It is found that the low optical transmittance (<75%) of the ultradrawn UHMWPE/graphene composite films is drastically improved (>90%) by adding 2-(2H-benzontriazol-2-yl)-4,6-ditertpentylphenol (BZT) as a second additive. This high transmission is interpreted in terms of a reduced void content in the composite films and the improved dispersion of graphene both of which decrease light scattering. The high thermal conductivity is attributed to the π-π interaction between BZT and graphene. In addition, a high specific thermal conductivity of ≈75 W m^-1 K^-1 ρ^-1 of the ultradrawn UHMWPE/graphene/BZT composite films is obtained, which is higher than most metals and polymer nanocomposite. These transparent films are potentially excellent candidates for thermal management in various applications due to a combination of low density, ease of processing, and high thermal conductivity.