Polymer Nanowire Arrays With High Thermal Conductivity and Superhydrophobicity Fabricated by a Nano-Molding Technique

High thermal conductivity is helpful for thermal control and management, and superhydrophobicity can benefit fluid friction reduction and liquid droplet control in micro-/nanodevices. We report on a nano-molding technique that can prepare polyethylene nanowire arrays with high thermal conductivity (more than 10 W/m-K) and superhydrophobicity (contact angle >150 degrees). The thermal conductivities of the fabricated high-density polyethylene nanowire arrays with diameters of 100 nm and 200 nm, measured by a laser flash method, are about 2 orders of magnitude higher than their bulk counterparts. The estimated thermal conductivity of a single high-density polyethylene nanowire is as high as 26.5 W/m-K at room temperature, while the thermal conductivity of low-density polyethylene nanowire is a little smaller. The self-organized surfaces of polymer nanowire arrays are found to have micro-to-nanoscale hierarchical nanostructures, and have superhydrophobicity of greater than 150 degrees contact angles for water. We also measure the wettability of organic liquids, including glycerin, ethanol, paraffin liquid, and methyl silicone oil. We find glycerin gives hydrophobic wettability, but the others give hydrophilic wettabilities. This technique is promising for fabrication due to the advantages of simple fabrication, high quality, low cost, and mass production.