Exploiting the Hierarchical Morphology of Single-Walled and Multi-Walled Carbon Nanotube Films for Highly Hydrophobic Coatings

Self-assembled hierarchical solid surfaces are very interesting for wetting phenomena, as observed in a variety of natural and artificial surfaces. Here, we report single-walled (SWCNT) and multi-walled carbon nanotube (MWCNT) thin films realized by a simple, rapid, reproducible, and inexpensive filtration process from an aqueous dispersion, that was deposited at room temperature by a dry-transfer printing method on glass. Furthermore, the investigation of carbon nanotube films through scanning electron microscopy (SEM) reveals the multi-scale hierarchical morphology of the self-assembled carbon nanotube random networks. Moreover, contact angle measurements show that hierarchical SWCNT/MWCNT composite surfaces exhibit a higher hydrophobicity (contact angles of up to 137{\deg}) than bare SWCNT (110{\deg}) and MWCNT (97{\deg}) coatings, thereby confirming the enhancement produced by the surface hierarchical morphology.