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

2. Introductionlotus-effect Beautiful lotus flowers Water droplets Self-cleaning Bar = 20  m Surface roughness Barthlott, et al. Planta 1997, 202, 1

3. Hydrophobic surface with low surface energy water contact angle,  > 90° Self-Cleaning Properties  : contact angle on a rough surface  0 : 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

4. The force needed for a drop to move over a solid surface (F ): 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  LV is the surface tension of the liquid Contact angle hysteresis: Contact angle hysteresis:  A –  R or  LV (cos  R – cos  A ) Basic theory

5. 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

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

9. Bi-functional PDMS (2) 481246 (1) EFKA 3299 HO-(EO)n-OCH 2 CH 2 CH 2 -(Si(Me) 2 O)x-CH 2 CH 2 CH 2 O-(EO)n-OH n ca. 10 x ca. 20 EO = ethylene oxide, PO = propylene oxide HO-CH 2 CH 2 -OCH 2 CH 2 -(Si(Me) 2 O) n -CH 2 CH 2 O-CH 2 CH 2 -OH n=69

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

11. Water CA and hysteresis of PU film containing EFKA 3299 and cured at room temperature by approach 1 PU film with bi-functional EFKA3299 Surface wettability

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

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

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

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

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

17. Surface chemical composition PU film with mono-functional 480355 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 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 o C and 120 o C

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 o C

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

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

23. 2. Application of PDMS-modified PU films as anti-fouling coatings. 2. Application of PDMS-modified PU films as anti-fouling coatings. Future plans Coatings containing toxic materials Coatings containing toxic materials Non-toxic Systems Non-toxic Systems Fouling-release coatings based on silicones Fouling-release coatings based on silicones Perform well initially Perform well initially Soft, poor durability, short use life Soft, poor durability, short use life

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