Super‐Black Material Created by Plasma Etching Wood

Abstract

A super‐black wood with low reflectivity in the UV/Vis range is created by plasma modifying basswood surfaces. Here the super‐black wood is characterized, the process used to make it is described and its possible practical uses are discussed. Wood samples are exposed to oxygen glow‐discharge plasma. Transverse surfaces exposed to high‐energy plasma have a deep‐black velvety appearance. The reflectance of these surfaces is measured and compared with those of commercial super‐black materials. The reflectivity of samples over a narrower wavelength range is measured with a spectrophotometer and converted into lightness values. The microstructure and surface chemistry of super‐black wood are examined using SEM/X‐ray micro‐CT and FTIR spectroscopy, respectively. Transverse basswood samples modified with high‐energy plasma have reflectivity averaging 0.68% (300–700 nm). The super‐black color of plasma‐modified wood is retained when it is coated with gold/vanadium alloy indicating structural coloration. Plasma creates a low density, lignin‐enriched surface with deep pits, columns and tangled fibrils; features also found in synthetic super‐black materials. In conclusion, this method of creating a super‐black material by plasma‐modification of basswood does not require a lithography pre‐step, generates no liquid waste and, as is demonstrated here, can be used to prototype luxury consumer products.