Presentation is about superhydrophobic surfaces and its informational details.

1. L/O/G/O

3. :lacking
an affinity for water; unable to
absorb, or be wetted by water
Examples of hydrophobic molecules
include the alkanes, oils, fats, and
greasy substances in general.

4. :Repelling water to the
degree that droplets do not flatten but roll
off instead.
; broccoli, Brussels
sprout,cabbage, collard greens, tulip
leaves and the wings of butterfly

5. • Superhydrophobic: The contact angle of a
water droplet exceeds 150° and the sliding
angle is less than 10°.
• To get superhydrophobic surface we need;
Low surface energy
High surface roughness

6. Symbol of purity
Self-cleaning
Water-repellent
Water is easily
displaced

9. 90°

10. Contact
Angle:125°

12. • Surface tension= Surface energy (N/m2-
J/m2)
• For example; a balloon.

18. Energy
Low Hydrophobic
High Hydrophilic

19. The unique roughness of
superhydrophobic
surface forces water
droplets into spherical
drops that minimize
contact with the surface,
rolling off easily and
carrying away dirt and
other debris, leaving the
surface clean.

20. r=
𝑟𝑒𝑎𝑙 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎
𝑝𝑟𝑜𝑗𝑒𝑐𝑡𝑒𝑑 𝑠𝑢𝑟𝑓𝑎𝑐𝑒 𝑎𝑟𝑒𝑎
> 1
cos Θ
∗
= 𝑟 cos ΘE
The Wenzel wetting state. When water condenses on a
rough surface, it condenses from within the texture and
forms a droplet in the "sticky" Wenzel wetting state.
ΘE

21. ɸ 𝐬= % of solid
𝐜𝐨𝐬 𝚯
∗
= −𝟏 + ɸ 𝐬 (𝐜𝐨𝐬 𝚯 𝐄 + 𝟏)
ΘE
• For very rough surfaces
• Droplets mostly sitting on the
air pockets

23. METHODS TO PREPARE SUPERHYDROPHOBIC SURFACES
Lithography
Template
Electrospinning
Sol–gel
Layer-by-layer (LbL)
Etching
Chemical vapor deposition (CVD)
Electroless galvanic deposition
Anodic oxidation
Electrochemical deposition.
RECENT ADVANCES IN DESIGNING SUPERHYDROPHOBIC SURFACES
JOURNAL OF COLLOID AND INTERFACE SCIENCE
Elena Celia, Thierry Darmanin, Elisabeth Taffin de Givenchy, Sonia Amigoni, Frédéric Guittard

24. SOL-GEL METHOD
A gel consists of a three dimensional continuous network, which
encloses a liquid phase.
A sol is a stable dispersion of colloidal particles or polymers in a solvent.

25. SOL-GEL METHOD
The sol-gel coating process usually consists of 4 steps:
1-Dispersion in a liquid to form a sol
2-Deposition of sol solution
3-Polymerization & Gel formation
4-Final heat treatments and formation of amorphous or crystalline coating
In a typical sol–gel process, the precursor is converted into a glassy
material through a series of
hydrolysis and polycondensation reactions

26. ADVANTAGES AND DISADVANTAGES OF SOL-GEL METHOD
Produce thick coating to provide corrosion
protection performance.
Easily shape materials into complex
geometries in a gel state.
Low temperature sintering capability
Simple, economic and effective method to
produce high quality coatings
Weak bonding
Low wear-resistance
High permeability
Difficult controlling of porosity.

27. LAYER-BY-LAYER(LbL) METHOD
The LbL is a method by which thin films, particularly of oppositely charged layers, are deposited.
The films are formed by depositing alternating layers of oppositely charged materials with wash steps
in between.

28. LAYER-BY-LAYER(LbL) METHOD
Water drops and the resulting
contact angle on a glass surface
spread with various LbL coats. Due
to the nano-roughness, the
properties of the surface can be
infinitely adjusted from super
hydrophilic to super hydrophobic.

29. CHEMICAL VAPOR DEPOSITION(CVD)
CVD is a deposition process where chemical precursors are transported in the vapor
phase to decompose or react on a heated substrate to form a film.

30. PLASMA ENHANCED CHEMICAL VAPOR
DEPOSITION (PECVD)
PECVD processing allows deposition at lower temperatures, which is
often critical in the manufacture of semiconductors.

31. (Xu Deng, Lena Mammen, Hans-Jürgen Butt, Doris
Vollmer)

32. • A major goal in coating research is to
design self-cleaning surfaces.
• A porous deposit candle soot was coated
with 25nm thick silica shell.The surface to
be coated in our case a glass slide is held
above the flame of a paraffin candle.

33. CVD
Coated the
soot layer with
a silica shell

36. Easily Fabricated
Transparent
Oil-rebounding Superamphiphobic
Roll of easily

37. (Jin Yang, Zhaozhu Zhang, Xuehu Men, Xianghui)

38. Polystrene Functionized Carbon Nanotubes
Using Spray Coating Method(Low Cost and
Simple Method)
Coated With Polystrene

39. 4-Hydroxy-
2,2,6,6-tetra-
methyk
piperidinooxy
Styrene N,N-dimethyl-
formamide
Benzoyl
peroxide

40. Figure: The water CA(inset) on the MWCNT-PS
nanocomposite reaches to 160°
1-3° tilting
angle

41. Figure:The transmittance spectra of the MWCNT–PS film

42. Contac angle 160°
Transmittance about 78%
Self Cleaning Coatings
Heating and electromagnetic
interference shielding

45. SiO2 Nanoparticles+Toluene+Dodecyltri
chlorosilane
Ethanol
1-propanol
1-butanol

46. Contact angle meter
Scanning electron microscopy

47.  Sedimentation rate was faster in lower alcohol.
Average size of aggregation:
470 nm in ethanol
410 nm in 1-propanol
350 nm in 1-butanol

48. • CA>150° and SA<10°
• Only ethanol because it has the
shortest hydrocarbon chains.

49. Ethanol 1-butanol
a)
b)
c)
d)
e)
f)
50µm
10µm
1µm

51. The simplicity of the process
No costly instruments
No extreme conditions
No special nanomaterials

53. Involves the transition of a system from a liquid «sol»
into a semi solid «gel» phase.
The dip coating method is use for synthesis of
transparent and uniform films.
Sol gel method+ dip coating method=silica films on
glass
The surface chemical modification of silica films using
TMCS

54. MTMS Methyltrimetho
xysilane
Hydrophobic C.A > 90°
TMCS Trimethychloro
silane
Superhydrophobi
c C.A > 150°
HMDZ Hexamethyldisi
lazane
Ultrahydrophobic C.A > 120°

55. 1) Preparation of silica films using MTMS
2) Surface modification of the silica films
3) Annealing of the surface modified silica
films

56. Surface Modification of
HMDZ
Surface Modification of
TMCS

57. The water contact angle of the silica films for different percentages of TMCS and
HMDZ keeping silylation period constant at 2 h
The water contact angle of the silica films for different silylation period keeping
constant percentage (5%) of TMCS and HMDZ

58. HMDZ modified TMCS modified

59. A:TMCS
B:HMDZ

60. As deposited HMDZ modified TMCS modified

62.  Maintenance of cleanliness
 Ease in transportation
 Eliminates water based corrosion
Applicable to practically any
substrate of nearly any size
Not limited to flat surfaces
Coatings can be made transparent
PROPERTIES

63. SELF-CLEANING
ANTI-FOULING ANTI-ICING
ANTI-CORROSIONANTI-SALINATION
ANTI-FRICTIONANTI-CLOTTING
MOLD RESISTANCE
WHY DO WE PREFER SUPERHYDROPHOBIC SURFACES?

64. Anti-icing coatings on power lines, insulators, buildings, driveways etc.
Lightly washed Navy Radome Samples
Modified
Superhydrophobic
Coating
Uncoated
Reference
Sample
APPLICATIONS

65. ANTI-ICING

66. Anti-corrosive treatments for metals such as rims
ANTI-CORROSIVE

67. ANTI-SALINATION

68. ANTI-FOULING

69. SELF-CLEANING