Beech wood cross sections as natural templates to fabricate superhydrophobic surfaces

Inspired by the hierarchical and porous wood microstructure, polydimethylsiloxane (PDMS)-positive replicas of beech (Fagus sylvatica) cross sections, with superhydrophobic properties, were fabricated. Microtomed transverse sections of beech wood were directly used as templates, and an accurate replication of the anatomical wood features (vessels and fibers) was obtained. The resulting PDMS-positive replicas show an arrangement of pillars, contributing to surface structuration. By adjusting the PDMS pre-curing time, the extent of PDMS penetration could be controlled inside the wood capillaries, inducing the formation of pillars with various aspect ratios. The wettability of the templated surfaces as a function of the different pillars heights was studied, and the optimal pillar aspect ratio was identified to enhance the hydrophobicity of the PDMS structured surfaces (reaching a water contact angle of 156 degrees). Fagus sylvatica wood cross sections are therefore simple, scalable, and inexpensive templates to manufacture structured surfaces, with the possibility to adjust wettability according to application needs.