Highly Efficient and Large-Scale Fabrication of Superhydrophobic Alumina Surface with Strong Stability Based on Self-Congregated Alumina Nanowires

In
this study, a large-area superhydrophobic alumina surface with a series
of superior properties was fabricated via an economical, simple, and
highly effective one-step anodization process, and subsequently modified
with low-surface-energy film. The effects of the anodization parameters
including electrochemical anodization time, current density, and electrolyte
temperature on surface morphology and surface wettability were investigated
in detail. The hierarchical alumina pyramids-on-pores (HAPOP) rough
structure which was produced quickly through the one-step anodization
process together with a low-surface-energy film deposition [1H,1H,2H,2H-perfluoro­decyl­triethoxy­silane (PDES) and stearic
acid (STA)] confer excellent superhydrophobicity and an extremely
low sliding angle. Both the PDES-modified superhydrophobic (PDES-MS)
and the STA-modified superhydrophobic (STA-MS) surfaces present fascinating
nonwetting and extremely slippery behaviors. The chemical stability
and mechanical durability of the PDES-MS and STA-MS surfaces were
evaluated and discussed. Compared with the STA-MS surface, the as-prepared
PDES-MS surface possesses an amazing chemical stability which not
only can repel cool liquids (water, HCl/NaOH solutions, around 25 °C),
but also can show excellent resistance to a series of hot liquids
(water, HCl/NaOH solutions, 30–100 °C) and hot beverages
(coffee, milk, tea, 80 °C). Moreover, the PDES-MS surface also
presents excellent stability toward immersion in various organic solvents,
high temperature, and long time period. In particular, the PDES-MS
surface achieves good mechanical durability which can withstand ultrasonication
treatment, finger-touch, multiple fold, peeling by adhesive tape,
and even abrasion test treatments without losing superhydrophobicity.
The corrosion resistance and durability of the diverse-modified superhydrophobic
surfaces were also examined. These fascinating performances makes
the present method suitable for large-scale industrial fabrication
of chemically stable and mechanically robust superhydrophobic surfaces.