Superhydrophobic Nanocomposites Coating Using ... · International Journal of Applied Engineering...

International Journal of Applied Engineering Research ISSN 0973-4562 Volume 12, Number 24 (2017) pp. 16032-16038

© Research India Publications. http://www.ripublication.com

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Superhydrophobic Nanocomposites Coating Using Electrospinning

Technique on Different Materials

Prof. Dr. Balkees Mohammed Diaa

University of Technology, Baghdad, Iraq.

Hassan Talal Jaafar

University of Technology, Baghdad, Iraq.

Abstract

Superhydrophobic coating were fabricated using

electrospinning technique on different substrates (glass,

ceramic and metal) , polymer solutions of (PS/DMF) and

(PMMA/THF) were used in different range of composition for

each solutions, also epoxy and nano TiO2 were used to fabricate

nanocomposites. Contact angle, surface tension, viscosity were

calculated for all specimens. SEM showed the morphology of

the surfaces and show that (20%PS/DMF) has a higher amount

of beads attached with nanofibers and the number of these

beads increased with increasing the viscosity of the polymer

solution (PS/DMF) , (20%PS/DMF) owned a larger contact

angle about (160.739o) for metal substrate and show a

superhydrophobicity for ceramic and glass substrate after

coating with (20%PS/DMF/TiO2). All the results were

discussed.

Keywords: (PS) Polystyrene, (PMMA)

Polymethylmethacrylate, (DMF) N,N-Dimethylformamide ,

(THF) Tetrahydrofuran , (TiO2) Titanium dioxide , (CA)

Contact angle , (SEM) Scanning electron microscope .

INTRODUCTION

In the last few years the interested is grown very much towards

superhydrophobic materials and coatings according to

engineering and nanotechnology requirements to achieve

material with the desired properties which are better than raw

materials. This research focused on studies the

superhydrophobic coating to obtain materials with special

surface properties by testing wettability of coated surfaces

(ceramic, glass and metal substrate) to defining hydrophobicity

and the characteristics of surfaces used, these materials surfaces

were chosen because they are very important in daily people

life use and industrial manufacturing which plays an important

role around this field research. Also tested to SEM (to show the

morphology texture of the surface).

Superhydrophobic coating is refers to static water on the

surface that tested by contact angle and acceded more than 150o

degree. There are different types of superhydrophobic surface

in nature like (lotus leaf, butterfly wings and desert beetle) ,

these examples has superhydrophobic and low adhesions

properties. These unique characteristics showed a great

interested by science and researchers that including (self-

cleaning, anti-corrosion, anti-wetting ..etc.). So this research

specialized on fabricate superhydrophobic coating to get what

almost in nature examples and achieve these unique desired

properties[1].

Electrospinning technique is one of the most efficient and

best method which become common and popular in the last few

years and increased interest by nanotechnology field because

of manufacturing and production of nanofibers polymer with

diameter ranging from (2nm - 5μm). In general, electrospinning

technique contains syringe pump, high voltage source and

collector, the polymer solution put into syringe pump which

pushed in static flow rate and the needle connected to high

voltage source in range (3KV - 30KV)[2].

Electrospinning parameters are the measure of the resulting

material from electrospinning technique that effect on the

properties of the fibers manufactured by this method. There are

many types of electrospinning parameters (Solution

parameters, Instrumental parameters and Ambient or

Environmental parameters)[3].

Solution parameters which include (viscosity and surface

tension). Viscosity considered an important factor that effect

on electrospinning technique , the most important factors

affecting on viscosity is molecular weight and the

concentration of the polymer. Surface tension is also one of

the important factor affecting on electrospinning technique

which effect by the composition of different polymer solution

this will result in changing the surface tension. When there is

high ratio of free solvent molecules, these molecules will mixed

together and will form beads[4].

Instrumental parameters (Applied voltages, Needle-

Collector distance and Feeder rate) in general voltage must be

applied in suitable way that will form the Taylor cone. By

increasing voltage the electrostatic repulsive force on the

polymer solution increased and this result by reducing the

diameter of manufactured fiber[5].

Ambient or environmental parameters (humidity,

temperature and atmosphere), which has important effect on the

form of fiber produced by electrospinning technique[5].

Contact angle, studies the wettability of the surface is very

important in this research which include the perusal of contact

angle test as primary data, and testing the degree of wettability

when the droplet of water touches the coated surface. Contact

angle divided to many sections and every sections include how

much wettability and resistance of the surface to the droplet ,

mailto:[email protected]

mailto:[email protected]



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specimens in this research will studied by this test to determine

the wettability of the surface that made by electrospinning

technique, and these sections of CA are (figure (1) shows CA

range and its sections) [6] :

Figure 1: Contact Angle Sections and Range.

Materials Used :

Polystyrene (PS) granules from panreac Co. for

didactic (Barcelona - Espan).

Polymethylmethacrylate (PMMA) powder from

MME. , (Dubai - UAE).

Nano titanium dioxide (TiO2) nano particle with

diameter (20nm - 40nm) from micxy reagent

company (China).

N,N-Dimethylformamide (DMF) solution from

sigma-aldrich (SCR). Tetrahydrofuran (THF) solution from (CDH)

Ltd. (New Delhi - India).

Epoxy resin from (sikadu-®52) Co. (USA).

Ethanol (ethyl alcohol) sigma-aldrich (SCR).

Figure 2: Materials Used in The Research.

Experimental Part : The substrate of specimens used (ceramic, glass and metal)

each of them has washed with distilled water and cleaned with

alcohol for 5 min then dried with oven at 35-50o temperature to

obtain a smooth surface without contamination and scratches to

the surface[7]. Figure (3) shows specimens prepared before

coating.

Figure 3: Specimen prepared for (Ceramic, Glass and Metal)

before coating.

For first surface specimen is metal , that coated with (PS/DMF)

solution and (EP) as matrix for (PS/DMF) to make the layer of

(PS/DMF) solution coating good enough to adhesion with

surface of the specimen , also specimen of metal surface is

coated with (PMMA/THF) solution without need EP as matrix

to make adhesion with surface.

The preparation of the (PS/DMF) solution was prepared by

dissolve PS granules in DMF solute in different %wt

composition in range of (5, 10, 15 and 20%wt) of PS granules

and put on a magnetic stirrer for 12 hours to make an

homogenous polymer solution, the percentage of

(20%PS/DMF) was depended in this research because it shows

the larger contact angle over other percent which shows about

(160.739o) degree. EP resin was prepared by ratio of 90:10 (EP

: Hardener) and also diluted with ethanol in percent of 25%wt,

the reason of diluted EP solution that much is to make the

viscosity of the solution good enough to go out the tip of needle

of syringe pump easily[4-8].

The preparation of the (PMMA/THF) solution was prepared by

dissolve PMMA powder in THF solute in different %wt

composition in range of (3, 4 and 5%) of PMMA powder and

put on a magnetic stirrer for 6 hours to make an homogenous

polymer solution, the percentage of (4%PMMA/THF) was

depended in this research because it shows the larger contact

angle over other percent which shows about (151.856o)

degree[9]. Figure (4) shows Metal substrates coated with

(PS/DMF) and (PMMA/THF) solutions.

Figure 4: Metal substrates coated with (PS/DMF) and

(PMMA/THF) solutions.



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For ceramic and glass surface specimens it has coated with

(20%PS/DMF/TiO2) solution and EP as matrix for (PS/DMF),

TiO2 nanoparticle was used in known percentage of %wt that

mixed with (20%PS/DMF) solution to enhance the

hydrophobicity of the ceramic and glass surface in way better

than surfaces only coated with (20%PS/DMF) solution[10].

Figure (5) shows Ceramic and Glass substrates that coated with

(20%PS/DMF/TiO2) solution.

Figure 5: Ceramic and glass substrates coated with

(20%PS/DMF/TiO2) solution.

Set up of electrospinning technique, in general electrospinning

technique contains syringe pump, high voltage source and

collector, in the beginning, this method contains of 3 electrode,

the polymer solution that prepared as explained above put into

syringe pump, the first electrode is connected to the needle of

the syringe pump, the needle diameter is very small and is

connected with high voltage source (8.5KV for PS/DMF),

(6.5KV for PMMA/THF) and (3.5KV for EP), the syringe used

in this research is 3ml size, which pushed in static flow rate.

The second electrode is connected to the board that put the

specimen or substrate on it which called collector and the third

electrode is connected to earth to prevent electrical fault shock.

When an electrical field is granted a boost to the needle of the

syringe pump it produce electro static power that wok on

changing the surface tension of the solution and deform the

shape of spray and make it like conical spiral (Taylor cone) on

the collector board and when the voltage increased the change

in the shape of the droplet increased, when the voltage

stabilized it work on evaporate the solute and fibers produced

by this technique only stay on the substrate or specimen[2-3].

The electrospinning technique can be used for making fibers

with aligned fibrous structure achieved using roller tube

collector (used aligned for metal surface) and non- aligned

fibrous structure achieved using a plate collector (used non-

aligned for ceramic and glass surface). According to the type of

collector used. Also electrospinning apparatus is available in

two different set up, vertical set up and horizontal set up. In this

research the method set up in horizontal method. And the

following figure (6) show electrospinning technique method

preparation and set up as explained previous section.

Figure 6: The Electrospinning Technique Method Preparation

and Set-up .

RESULT AND DISCUSSION

Table (1) shows the result of prepared polymer solutions after

tested to viscosity and surface tension tests. For viscosity show

increasing by increase the amount of polymers percentage that

mixed with solute for both PS and PMMA. By increasing

viscosity of the PS/DMF solution little higher using PS

granules with higher molecular weight or increasing the PS

concentration in the solution, then a mixture of fibers and beads

will be obtained. For (PMMA/THF) the viscosity will be in

appropriate range this will result with smooth micro or

nanofibers.

Surface tension has a direct correlation with viscosity for

(PS/DMF) solutions, and indirect correlation for

(PMMA/THF) solution cause due to the shape of PS granules

as compared to the PMMA powder which make surface tension

more motive to PS than PMMA polymer solution, also the

solute used has effect to surface tension either , figure (7) shows

relation between viscosity and surface tension. The remaining

results are obtained with test as collected receive scan, surface

tension has a direct correlation with actual tension , and for

shear stress it shows increasing with PS and decreasing with

PMMA and this due to the amount of polymers added to the

solute and due to prepared environment. Finally for shear rate

is an constant number and resultant with the viscosity test

device. Figure (8) shows relation between shear stress and

shear flow rate[6].

Table 1: Viscosity, surface tension, actual tension, shear

stress and shear rate results for polymer solutions prepared .

Polymer Solution Viscosity

(m2.sec-1)

Surface

Tension

(N.m-2)

Actual

Tension

(N.m-2)

Shear

Stress

(N.m-

2)

Shear

Rate

(sec-1)

(5%PS/DMF) 5.93 28.47 20.64 11.88 20

(10%PS/DMF) 11.86 30.17 21.87 9.40 40

(15%PS/DMF) 17.79 31.16 22.59 7.34 11

(20%PS/DMF) 23.72 32.53 23.58 7.33 11

(3%PMMA/THF) 9.7 20.7 20.72 2.35 24

(4%PMMA/THF) 15 20.59 20.59 3.6 24

(5%PMMA/THF) 27 20.2 20.14 6.7 24

(5%PS/DMF/TiO2) 20.62 21.03 13.23 15.45 25



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Figure 7: Relation between viscosity and surface tension.

Figure 8: Relation between shear stress and shear flow rate.

Contact angle has tested for all specimens prepared before and

after coating by electrospinning technique, contact angle

measured for specimens (ceramic, glass and metal) before

coating and it show that all surface was hydrophilic. For

ceramic surface shows (0o) CA because of high porosity of the

surface which result as a superhydrophilic material, for glass

surface shows (47.647o) CA and for metal surface shows

(60.493o) which both materials considered as hydrophilic

materials. Figures (9) shows contact angle test for (ceramic,

glass and metal) before coating .

Figure 9 : Contact angle for (ceramic, glass and metal) before

coating A. ceramic surface CA=0O, B. glass surface

CA=47.647o and C. metal surface CA=60.493o

Contact angle has tested for metal specimens after coating by

electrospinning technique, with different percent of (PS/DMF)

solution , and it shows surfaces that coated with (5%PS/DMF)

has contact angle of (121.730o) and for surface coated with

(15%PS/DMF) has contact angle of (121.851o) and both coated

surface mentioned has a hydrophobic properties, while surfaces

coated with (10%PS/DMF) and surface coated with

(20%PS/DMF) has a superhydrophobic properties, in which

(10%PS/DMF) has contact angle of (150.836o) and

(20%PS/DMF) has contact angle of (160.739o). the surface

coated with (20%PS/DMF) has higher contact angle compared

to other coated specimen because of the moderate viscosity and

good surface tension that polymer solution of (20%PS/DMF)

has it. Figures (10) shows contact angle test for metal

specimens coated with different percent of (PS/DMF) solution.

Figure 10: CA. for metal specimens coated with different

percent of (PS/DMF) solution. A. (5%PS/DMF)

CA=121.730O,

B. (10%PS/DMF) CA=150.836O, C.(5%PS/DMF)

CA=121.851O and D. (5%PS/DMF) CA=160.739O.

Contact angle has tested for metal specimens after coating by

electrospinning technique, with different percent of

(PMMA/THF) solution , and it shows surfaces that coated with

(3%PMMA/THF) has contact angle of (100.639o) and for

surface coated with (5%PMMA/THF) has contact angle of

(113.201o) and both coated surface has a hydrophobic

properties, while surfaces coated with (4%PMMA/THF) has a

superhydrophobic properties which has contact angle of

(151.856o) and owns a higher contact angle compared to other

coated specimen because of the moderate applied voltage for

(PMMA/THF) solution. Figures (11) shows contact angle test

for metal specimens coated with different percent of

(PMMA/THF) solution.

Figure 11: CA. for metal surface coated with different

percent of (PMMA/THF) solution. A. (3%PMMA/THF)

CA=100.639O, B. (4%PMMA/THF) CA=151.856O and

C. (5%PMMA/THF) CA=113.201O .



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Contact angle has tested for ceramic and glass specimens after

coating by electrospinning technique with (20%PS/DMF/TiO2)

solution , and it shows contact angle of (154.285o) for glass

coated surface and contact angle of (154.378o) for ceramic

coated surface. This shows in excellent enhancement for

ceramic from (CA=0O) superhydrophilic to superhydrophobic

about (CA=154o). Figures (12) shows contact angle test for

ceramic and glass specimens coated with (20%PS/DMF/TiO2)

solution.

Figure 12: CA. for ceramic and glass coated with

(20%PS/DMF/TiO2) solution. A.Glass surface CA=154.285O

and B. Ceramic surface CA=154.378O.

Specimen of (20%PS/DMF)-Metal , (4%PMMA/THF)-Metal

and (20%PS/DMF/TiO2)-Glass, that owns best contact angle as

compared to other specimens has tested to scanning electron

microscope test (SEM) to see the morphology of the surfaces,

and show that specimen of (20%PS/DMF) have higher amount

of beads and this due to the moderate viscosity or increasing of

PS concentration in the solution, then a mixture of fibers and

beads will be obtained, and due to unbalanced applied voltages

in range of (8.5KV - 9.2KV) also the use of roller tube collector

to obtain alignment nanofibers. As in figure (13), while in

PMMA show beads and defect and this forms because

(PMMA/THF) solution has low viscosity also not need a matrix

because already adhesion with surface so it appears in this way

as in the figure (14), and for (20%PS/DMF/TiO2) shows a great

bonding between nanofibers because of the presence of TiO2

nanoparticles which owns very high surface area that helps to

nanofibers bond to each other with less beads. as in the figure

(15) [11].

Table 2: Shows average contact angle for all specimens.

Polymer Solution Contact Angle

Left (CA_L)

Contact Angle

Right (CA_R)

Contact Angle

Average (CA_AV)

Ceramic - None 0 0 0

Glass - None 47.647 47.647 47.647

Metal - None 60.493 60.493 60.493

(5%PS/DMF) - Metal 120.127 123.333 121.730

(10%PS/DMF) - Metal 146.392 155.281 150.836

(15%PS/DMF) - Metal 117.558 126.145 121.851

(20%PS/DMF) - Metal 158.019 163.459 160.739

(3%PMMA/THF) - Metal 100.639 100.639 100.639

(4%PMMA/THF) - Metal 151.856 151.856 151.856

(5%PMMA/THF) - Metal 111.758 114.645 113.201

(5%PS/DMF/TiO2) -

Ceramic

153.581 155.175 154.378

(5%PS/DMF/TiO2) - Glass 154.285 154.285 154.285

Figure 13: SEM images for (20%PS/DMF) - Metal substrate.



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Figure 14: SEM images for (4%PMMA/THF) - Metal substrate.

Figure 15: SEM images for (20%PS/DMF/TiO2) - Glass substrate.

CONCLUSION

(20%PS/DMF) owns the higher contact angle about

(160.739o) as compared to other (PS/DMF) coated

specimens. (4%PMMA/THF) has the higher contact

angle about (151.856o) as compared to other

(PMMA/THF) coated specimens.

(20%PS/DMF) owns the higher amount of beads due to

the viscosity of (PS/DMF) solution.

(20%PS/DMF) has higher viscosity and surface tension,

(4%PMMA/THF) has moderate viscosity and surface

tension.

Excellent enhancement for (ceramic substrate) after

coating by electrospinning technique with

(20%PS/DMF/TiO2) solution and contact angle changed

from superhydrophilic (0o) to a superhydrophobic

(154.378o) , and the ceramic surface become repels

water instead of absorb water.

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