Wood Composites with Wettability Patterns Prepared by Controlled and Selective Chemical Modification of a Three-Dimensional Wood Scaffold

Wood-composite materials with patterned wetting properties were synthesized by applying hydrothermal growth of ZnO rods into a wood scaffold. We exploited the natural morphological features of wood, to selectively modify the wood material via a self-directed deposition of ZnO in the biological scaffold. Characterizations using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray powder diffraction confirmed the successful surface modification and revealed the predominant growth of ZnO rods on earlywood (EW) regions. The wetting properties of these new wood-composite materials have been extensively investigated to study the influence of the grooved wood surface structure and its chemical heterogeneity on the wettability. We demonstrate that the ZnO-wood samples have alternating hydrophilic and hydrophobic strips, corresponding to the EW and latewood grains from the native wood, and that the surfaces are endowed with an interesting anisotropic wetting property. Using these special wetting properties, we further modified ZnO-wood samples with inorganic and organic compounds and we report on basic experiments to show potential applications, in the design of biphasic materials and the control of water droplet movement on surfaces.