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Low Surface Energy PU Film With Small Contact Angle Hysteresis

Low Surface Energy PU Film With Small Contact Angle Hysteresis. Dou Qizheng 05-09-19. Beautiful lotus flowers. Water droplets. Self-cleaning. Surface roughness. Bar = 20 m. Introduction. lotus-effect. Barthlott, et al. Planta 1997 , 202 , 1.

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Low Surface Energy PU Film With Small Contact Angle Hysteresis

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

  2. Beautiful lotus flowers Water droplets Self-cleaning Surface roughness Bar = 20 m Introduction lotus-effect Barthlott, et al. Planta1997, 202, 1

  3. Proper surface roughness (Lotus-alike structure) Wenzel eq. Cassie-Baxter eq. : contact angle on a rough surface 0: contact angle on a projected ‘smooth’ surface Surface roughnessenhances the hydrophobicity of hydrophobic surfaces Self-Cleaning Properties • Hydrophobic surface with low surface energy • water contact angle,  > 90° • Low roll-off angles ------ small contact angle hysteresis

  4. 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)

  5. 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

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

  7. Polymer Matrix: Solventless Liquid Oligoesters (SLO) and N3600 (cross-linker)

  8. 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)

  9. Bi-functional PDMS (1) EFKA 3299 HO-(EO)n-OCH2CH2CH2-(Si(Me)2O)x-CH2CH2CH2O-(EO)n-OH 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

  10. Mono-functional PDMS Mono-hydroxyl terminated PDMS (480355): n= 63

  11. 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

  12. Surface wettability PU film with bi-functional 481246 PU film containing 481246 by approach 1

  13. Surface wettability PU film with bi-functional 481246 PU film containing 481246 by approach 1

  14. Surface wettability PU film with mono-functional 480355 PU film containing 480355 by approach 2

  15. Surface wettability PU film with mono-functional 480355 PU film containing 480355 by approach 2

  16. Surface chemical composition PU film with bi-functional 481246 PU film containing 481246 and cured at 80 oC

  17. 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.

  18. 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.

  19. 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 by0.07%wt (PDMS)63-OH and cured under 40 oC and 120 oC

  20. 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 by0.07%wt (PDMS)63-OH or 0.08%wt (PDMS)69-(OH)2 and cured under 80 oC

  21. Model PU film containing EFKA 3299 PU film containing 480355 PU film containing 481246

  22. 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.

  23. 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

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

  25. THANK YOU FOR YOUR ATTENTION

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