Low Surface Energy PU Film With Small Contact Angle Hysteresis Dou Qizheng 05-09-19

Low Surface Energy PU Film Low Surface Energy PU Film With Small Contact Angle With Small Contact Angle

HysteresisHysteresis

Dou QizhengDou Qizheng

05-09-1905-09-19

IntroductionIntroduction

lotus-effectlotus-effect

Beautiful lotus flowers

Water droplets

Self-cleaning

Bar = 20 m

Surface roughness

Barthlott, et al. Planta 1997, 202, 1

• Hydrophobic surface with low surface energy water contact angle, > 90°

Self-Cleaning Properties

201

0

f-cosfcos

coscos

r

: contact angle on a rough surface0: contact angle on a projected ‘smooth’ surface

Surface roughness enhances the hydrophobicity of hydrophobic surfaces

• Proper surface roughness (Lotus-alike structure)Wenzel eq.

Cassie-Baxter eq.

•Low roll-off angles ------ small contact angle hysteresis

The force needed for a drop to move over a solThe force needed for a drop to move over a solid surface (id surface (FF ): ):

F F ~ ~ LVLV (cos (cos RR – cos – cos AA) ) LVLV is the surface tension of the liquid is the surface tension of the liquid

Contact angle hysteresis:Contact angle hysteresis:AA – – RR or or LVLV (cos (cos RR – cos – cos AA) )

Basic theory

Water contact angle:

• Advancing: 120º, receding: 60-70º

• Huge hysteresis: primarily due to the surface reorganization during the contact angle measurements.

PDMS

• Hydrophobic

• High MW to limit surface reorganization

Fluorinated Polyurethane Films

LEIS (low-energy ion scattering)

First atomic layer, only F and C can be detected

ExperimentalExperimental

Preparation of low-surface energy filmsPreparation of low-surface energy films

Polyurethane as polymer matrixPolyurethane as polymer matrix

Poly (dimethyl siloxane) (PDMS) will be usPoly (dimethyl siloxane) (PDMS) will be used as a low-surface energy agented as a low-surface energy agent

Polymer Matrix: Polymer Matrix: SSolventless olventless LLiquid iquid OOligoesters (SLO) and ligoesters (SLO) and N3600 (cross-linker)N3600 (cross-linker)

SLO

x][4 4)()(HO CH2 OC X CO CH2 OH

O O

N3600

N

O

O N

N CH2 N

O

CH2

C ONCO CH2 6)(

6)(

6)( N C O

X = equimolar mixture of (CH2)3, (CH2)4 and (CH2)7

Polyurethane films modified with Polyurethane films modified with hydroxyl-terminated PDMShydroxyl-terminated PDMS

PDMS + SLO + N3600 → PU film of low

Approach 1

Approach 2

PDMS + N3600 → partially PDMS-modified N3600

SLO + N3600 + PDMS-N3600 → low PU(To increase the miscibility between PDMS and other components)

Bi-functional PDMSBi-functional PDMS

(2) 481246

(1) EFKA 3299HO-(EO)n-OCH2CH2CH2-(Si(Me)2O)x-CH2CH2CH2O-(EO)n-OH

n ca. 10x ca. 20EO = ethylene oxide, PO = propylene oxide

HO-CH2CH2-OCH2CH2-(Si(Me)2O)n-CH2CH2O-CH2CH2-OH

n=69

Mono-hydroxyl terminated PDMS (480355):

CH3Si

OSi

OSi O

OH

CH3

CH3

CH3

CH3

CH3

CH3

n

n= 63

Mono-functional PDMSMono-functional PDMS

Water CA and hysteresis of PU film containing EFKA 3299 and cured at room temperature by

approach 1

PU film with bi-functional EFKA3299PU film with bi-functional EFKA3299

Surface wettabilitySurface wettability

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.220

25

30

35

40

45

Hys

tere

sis

(o )

Si%wt

Hysteresis

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2

50

60

70

80

90

100co

nta

ct a

ng

le (o )

Advancing CA Receding CA

PU film with bi-functional 481246PU film with bi-functional 481246Surface wettabilitySurface wettability

PU film containing 481246 by approach 1

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

50

60

70

80

90

100

110

Co

nta

ct a

ng

le (

o )

Si%wt

40 oC cured advancing CA

40 oC cured receding CA





PU film with bi-functional 481246PU film with bi-functional 481246Surface wettabilitySurface wettability


0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.0720

25

30

35

40

45

CA

hys

tere

sis

(o )

Si%wt

40 oC cured CA hysteresis




PU film with mono-functional 480355PU film with mono-functional 480355Surface wettabilitySurface wettability

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.0745

50

55

60

65

70

75

80

85

90

95

100

105

110

115C

on

tact

an

gle

(o )

Si%wt








PU film with mono-functional 480355PU film with mono-functional 480355Surface wettabilitySurface wettability

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

20

25

30

35

40

CA

hys

tere

sis

(o )

Si%wt




Surface chemical compositionSurface chemical compositionPU film with bi-functional 481246PU film with bi-functional 481246

PU film containing 481246 and cured at 80 oC

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.070

5

10

15

20 0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

1

2

3

4S

i%

Si%wt

10nm 80oC cured

5nm 80oC cured

N%

10nm 80oC cured

5nm 80oC cured

Surface chemical compositionSurface chemical compositionPU film with mono-functional 480355PU film with mono-functional 480355

The chemical composition (Si%) of the PU films which were modified by different amount of 480355480355 and cured under different temperature.

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0

10

200.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0

10

200.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0

10

20S

i%

Si%wt

5nm/T=40 oC

10nm/T=40 oC

Si%

5nm/T=80 oC

10nm/T=80 oC

Si%

5nm/T=120 oC

10nm/T=120 oC


The chemical composition (N%) of the PU films which were modified by different amount of 480355480355 and cured under different temperature.

0.00 0.01 0.02 0.03 0.04 0.05 0.06 0.070

1

2

3

40.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0

1

2

3

40.00 0.01 0.02 0.03 0.04 0.05 0.06 0.07

0

1

2

3

4N

%

Si%wt

5nm/T=40 oC

10nm/T=40 oC

N%

5nm/T=80 oC

10nm/T=80 oC

N%

5nm/T=120 oC

10nm/T=120 oC


The chemical composition (N% and Si%) in different depth of the PU films which were modified by0.07%wt (PDMS)63-OH and cured under 40 oC and

120 oC

4 5 6 7 8 9 106

12

18

24 4 5 6 7 8 9 100

1

2

3S

i%

depth(nm)

N%

0.07% PDMS 120 oC

0.07% PDMS 40 oC

Surface chemical compositionSurface chemical compositionCompare the PU film with 480355 and Compare the PU film with 480355 and

481246481246

The chemical composition (N% and Si%) in different depth of the PU films which were modified by0.07%wt (PDMS)63-OH or 0.08%wt (PDMS)69-(OH)2 and cured under

80 oC

4 5 6 7 8 9 10

9

12

15

184 5 6 7 8 9 10

0.7

1.4

2.1

2.8

3.5S

i%

depth(nm)

Si/bi-func Si/mono-func

N%

N/bi-func N/mono-func

PU film containing EFKA 3299

PU film containing 480355

PU film containing 481246

ModelModel

1. Increase the roughness of the 1. Increase the roughness of the surface by adding some nano-surface by adding some nano-particles into the film as a additive to particles into the film as a additive to get a super-hydrophobic surface.get a super-hydrophobic surface.

Future plansFuture plans

2. Application of PDMS-modified PU 2. Application of PDMS-modified PU films as anti-fouling coatings.films as anti-fouling coatings.

Future plansFuture plans

Coatings containing toxic materialsCoatings containing toxic materials Non-toxic SystemsNon-toxic Systems

Fouling-release coatings based on siliconesFouling-release coatings based on silicones Perform well initiallyPerform well initially Soft, poor durability, short use lifeSoft, poor durability, short use life

AcknowledgementAcknowledgement

Dr. W. MingDr. W. Ming Prof. WangProf. Wang Prof. LemstraProf. Lemstra Dr. KarssenbergDr. Karssenberg EPG/SMG/SKT group membersEPG/SMG/SKT group members DPIDPI

Documents

Low Surface Energy PU Film With Small Contact Angle Hysteresis Dou Qizheng 05-09-19