Nanopin film is an experimental material in

nanotechnology Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal ...

developed in 2005 with unusual

superhydrophobic Ultrahydrophobic (or superhydrophobic) surfaces are highly hydrophobic, i.e., extremely difficult to wet. The contact angles of a water droplet on an ultrahydrophobic material exceed 150°. This is also referred to as the lotus effect, after the ...

properties . A droplet of water makes contact with the surface of this film and forms an almost perfect sphere with a

contact angle The contact angle is the angle, conventionally measured through the liquid, where a liquid–vapor interface meets a solid surface. It quantifies the wettability of a solid surface by a liquid via the Young equation. A given system of solid, liq ...

of 178 °. This happens because it is covered with

nanoscale The nanoscopic scale (or nanoscale) usually refers to structures with a length scale applicable to nanotechnology, usually cited as 1–100 nanometers (nm). A nanometer is a billionth of a meter. The nanoscopic scale is (roughly speaking) a lo ...

, topped-off pins or cones

perpendicular In elementary geometry, two geometric objects are perpendicular if they intersect at a right angle (90 degrees or π/2 radians). The condition of perpendicularity may be represented graphically using the '' perpendicular symbol'', ⟂. It c ...

to the surface. The surface is regarded as a

composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

with mostly air and a small fraction constituted by the tops of the cones. When the

of the cone material is sufficiently large,

Cassie's law Cassie's law, or the Cassie equation, describes the effective contact angle Theta, θc for a liquid on a chemically heterogeneous surface, i.e. the surface of a composite material consisting of different chemistries, that is non uniform throughout. ...

predicts large contact angle values for the composite. This particular nanopin film is produced with

borosilicate glass Borosilicate glass is a type of glass with silica and boron trioxide as the main glass-forming constituents. Borosilicate glasses are known for having very low coefficients of thermal expansion (≈3 × 10−6 K−1 at 20 °C), m ...

. A solution of CoCl₂•6H₂O or cobalt chloride hexahydrate is heated at 60

°C The degree Celsius is the unit of temperature on the Celsius scale (originally known as the centigrade scale outside Sweden), one of two temperature scales used in the International System of Units (SI), the other being the Kelvin scale. The d ...

for 24 hours in a chemical bath deposition to form a

brucite Brucite is the mineral form of magnesium hydroxide, with the chemical formula Mg( OH)2. It is a common alteration product of periclase in marble; a low-temperature hydrothermal vein mineral in metamorphosed limestones and chlorite schists ...

type cobalt(II) hydroxide layer with composition :CoOH_1.13Cl_0.09(CO₃)_0.39.0.05H₂0 The top coating is provided by

lauric acid Lauric acid, systematically dodecanoic acid, is a saturated fatty acid with a 12-carbon atom chain, thus having many properties of medium-chain fatty acids. It is a bright white, powdery solid with a faint odor of bay oil or soap. The salts and ...

in a separate step. A 3 square micrometer surface now contains on average 166 such cones with cone height of around 100 nm, and the cone diameter at the tip is 6.5 nm. The

prediction for this material with the

surface area The surface area of a solid object is a measure of the total area that the surface of the object occupies. The mathematical definition of surface area in the presence of curved surfaces is considerably more involved than the definition of ...

of 0.000612 and flat film

of 75 ° is 177.8 °.

References

# {{Note, 1 ''Superhydrophobic Perpendicular Nanopin Film by the Bottom-Up Process'' Eiji Hosono, Shinobu Fujihara, Itaru Honma, and Haoshen Zhou

J. Am. Chem. Soc. The ''Journal of the American Chemical Society'' is a weekly peer-reviewed scientific journal that was established in 1879 by the American Chemical Society. The journal has absorbed two other publications in its history, the ''Journal of Analytical ...

; 2005; 127(39) pp 13458 – 1345
AbstractSupporting info with pics
Nanomaterials

See also

References