Low Surface Energy PU Film With Small Contact Angle Hysteresis

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Low Surface Energy PU Film With Small Contact
Angle Hysteresis

• Dou Qizheng
• 05-09-19

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Introduction

• lotus-effect

Barthlott, et al. Planta 1997, 202, 1
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Self-Cleaning Properties

• Hydrophobic surface with low surface energy
• water contact angle, ? gt 90

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

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Basic theory

• The force needed for a drop to move over a solid
  surface (F )
• F ?LV (cos ?R cos ?A)
• ?LV is the surface tension of the liquid
• Contact angle hysteresis
• ?A ? R or ?LV (cos ?R cos ?A)

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Fluorinated Polyurethane Films

• Water contact angle
• Advancing 120º, receding 60-70º
• Huge hysteresis primarily due to the surface
  reorganization during the contact angle
  measurements.

LEIS (low-energy ion scattering) First atomic
layer, only F and C can be detected

• PDMS
• Hydrophobic
• High MW to limit surface reorganization

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Experimental

• Preparation of low-surface energy films
• Polyurethane as polymer matrix
• Poly (dimethyl siloxane) (PDMS) will be used as a
  low-surface energy agent

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Polymer Matrix Solventless Liquid Oligoesters
(SLO) and N3600 (cross-linker)
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Polyurethane films modified with
hydroxyl-terminated PDMS
Approach 1
PDMS SLO N3600 ? PU film of low ?
Approach 2
PDMS N3600 ? partially PDMS-modified N3600
SLO N3600 PDMS-N3600 ? low ? PU
(To increase the miscibility between PDMS and
other components)
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Bi-functional PDMS
(1) EFKA 3299
HO-(EO)n-OCH2CH2CH2-(Si(Me)2O)x-CH2CH2CH2O-(EO)n-O
H n ca. 10 x ca. 20 EO ethylene oxide, PO
propylene oxide
(2) 481246
HO-CH2CH2-OCH2CH2-(Si(Me)2O)n-CH2CH2O-CH2CH2-OH n
69
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Mono-functional PDMS
Mono-hydroxyl terminated PDMS (480355)
n 63
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Surface wettability
PU film with bi-functional EFKA3299
Water CA and hysteresis of PU film containing
EFKA 3299 and cured at room temperature by
approach 1
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Surface wettability
PU film with bi-functional 481246
PU film containing 481246 by approach 1
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Surface wettability
PU film with bi-functional 481246
PU film containing 481246 by approach 1
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Surface wettability
PU film with mono-functional 480355
PU film containing 480355 by approach 2
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Surface wettability
PU film with mono-functional 480355
PU film containing 480355 by approach 2
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Surface chemical composition
PU film with bi-functional 481246
PU film containing 481246 and cured at 80 oC
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Surface chemical composition
PU film with mono-functional 480355
The chemical composition (Si) of the PU films
which were modified by different amount of 480355
and cured under different temperature.
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Surface chemical composition
PU film with mono-functional 480355
The chemical composition (N) of the PU films
which were modified by different amount of 480355
and cured under different temperature.
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Surface chemical composition
PU film with mono-functional 480355
The chemical composition (N and Si) in
different depth of the PU films which were
modified by0.07wt (PDMS)63-OH and cured under 40
oC and 120 oC
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Surface chemical composition
Compare the PU film with 480355 and 481246
The chemical composition (N and Si) in
different depth of the PU films which were
modified by0.07wt (PDMS)63-OH or 0.08wt
(PDMS)69-(OH)2 and cured under 80 oC
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Model
PU film containing EFKA 3299
PU film containing 480355
PU film containing 481246
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Future plans

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

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Future plans

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

• Coatings containing toxic materials
• Non-toxic Systems
• Fouling-release coatings based on silicones
• Perform well initially
• Soft, poor durability, short use life

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Acknowledgement

• Dr. W. Ming
• Prof. Wang
• Prof. Lemstra
• Dr. Karssenberg
• EPG/SMG/SKT group members
• DPI

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THANK YOU FOR YOUR ATTENTION