Page 39 - Gas Wettability of Reservoir Rock Surfaces with Porous Media

Concept of Gas Wettability and Research Status CHAPTER 1 23

as honeycomb, columnar, and island-shaped alignment of carbon nano-
tubes in the film. The CAs of water on the surface of these films are all
larger than 160 degrees, and the roll angles are all smaller than 5
degrees. Professor Hozumi et al., prepared a super-hydrophobic film
generated using a mixture of tetramethylsiloxane and fluoroalkyl silane
with a microwave plasma enhancing chemical vapor deposition
(MWPECVD) method. In this case, the CA with water increases as the
total pressure of the reactant increases and reaches a maximum of 160
degrees. In addition, a transparent super-hydrophobic film with nano
structures can be produced on glass, silicon, and organic glass base by
the MWPEVCD method, using trimethylsiloxane as the material. Roig’s
research group constructed a super-hydrophobic porous silicone gel
structure using supercritical volatile solutions and modified the surface
chemically. Professor Mccarthy prepared a series of silicon surfaces in
different sizes and patterns, then treated them with silylated reagents to
obtain a super-hydrophobic structure.
7. Other methods
Electrospirming is a good technique for the production of ultra-fine
fiber. So far, it has been used in the production of super-hydrophobic
surfaces by many research groups. It places a polymer solution or poly-
mer melt in a high-voltage electrostatic field, and the electriferous poly-
mer liquid droplets are stretched under the effects of Coulomb tension.
When the electric field force is strong enough, the polymer liquid dro-
plets overcome the surface tension and form jet streams. During this
process, streams evaporate or solidify and finally fall over receiving
devices, forming micro and nanofiber membranes in a non-woven fab-
ric shape. Wen’s research group obtained a super-hydrophobic surface
with the combination of mulberry-shaped CaCO 3 /SiO 2 composite parti-
cles and PDMS self-assembly. The CA and roll angle of the water surface
area are up to 164 6 2.5 degrees and 5 degrees, respectively. Producing a
super-hydrophobic surface with femtosecond laser is the focus of
research groups at present. Zhou’s research group proposed a simple
and manageable method to produce a super-hydrophobic surface on
stainless steel. This is to mainly obtain a microstructure by irradiating
samples with a femtosecond laser, then making them silylated. The sur-
face CA obtained by this method is 166.3 degrees, and the roll angle is
4.2 degrees. Yuan et al., produced a micro-nano-structure hierarchical
rough Co 3 O 4 surface by combining simple solid-state reaction and sur-
face treatment. On this surface, the CA of water is up to 155 6 1.8
degrees, and the roll angle is 2 degrees. Furthermore, this surface retains
the hydrophobic features within the pH range of 3 to 14. Wang’s
research group put forward a novel one-step soaking method to con-
struct an environmentally stable super hydrophobic membrane on the
surface of metal. This method is simple and inexpensive, with no spe-
cific need for preconstructing surface microstructures and later low sur-
face energy material modification. Production on a large scale with