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. 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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Introduction

Beautiful lotus flowers Hysteresis

Water droplets

Self-cleaning

Surface roughness

Bar = 20 m

Introduction

lotus-effect

Barthlott, et al. Planta1997, 202, 1


Low surface energy pu film with small contact angle hysteresis

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


Low surface energy pu film with small contact angle hysteresis

Basic theory Hysteresis

  • 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)


Low surface energy pu film with small contact angle hysteresis

Fluorinated Polyurethane Films Hysteresis

  • 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


Experimental
Experimental Hysteresis

  • Preparation of low-surface energy films

  • Polyurethane as polymer matrix

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


Polymer matrix s olventless l iquid o ligoesters slo and n3600 cross linker
Polymer Matrix: HysteresisSolventless Liquid Oligoesters (SLO) and N3600 (cross-linker)


Polyurethane films modified with hydroxyl terminated pdms
Polyurethane films modified with hydroxyl-terminated PDMS Hysteresis

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)


Bi functional pdms
Bi-functional PDMS Hysteresis

(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


Mono functional pdms
Mono-functional PDMS Hysteresis

Mono-hydroxyl terminated PDMS (480355):

n= 63


Low surface energy pu film with small contact angle hysteresis

Surface wettability Hysteresis

PU film with bi-functional EFKA3299

Water CA and hysteresis of PU film containing EFKA 3299 and cured at room temperature by approach 1


Low surface energy pu film with small contact angle hysteresis

Surface wettability Hysteresis

PU film with bi-functional 481246

PU film containing 481246 by approach 1


Low surface energy pu film with small contact angle hysteresis

Surface wettability Hysteresis

PU film with bi-functional 481246

PU film containing 481246 by approach 1


Low surface energy pu film with small contact angle hysteresis

Surface wettability Hysteresis

PU film with mono-functional 480355

PU film containing 480355 by approach 2


Low surface energy pu film with small contact angle hysteresis

Surface wettability Hysteresis

PU film with mono-functional 480355

PU film containing 480355 by approach 2


Low surface energy pu film with small contact angle hysteresis

Surface chemical composition Hysteresis

PU film with bi-functional 481246

PU film containing 481246 and cured at 80 oC


Low surface energy pu film with small contact angle hysteresis

Surface chemical composition Hysteresis

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.


Low surface energy pu film with small contact angle hysteresis

Surface chemical composition Hysteresis

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.


Low surface energy pu film with small contact angle hysteresis

Surface chemical composition Hysteresis

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


Low surface energy pu film with small contact angle hysteresis

Surface chemical composition Hysteresis

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


Low surface energy pu film with small contact angle hysteresis

Model Hysteresis

PU film containing EFKA 3299

PU film containing 480355

PU film containing 481246


Future plans
Future plans Hysteresis

  • 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 plans1
Future plans Hysteresis

  • 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


Acknowledgement
Acknowledgement Hysteresis

  • Dr. W. Ming

  • Prof. Wang

  • Prof. Lemstra

  • Dr. Karssenberg

  • EPG/SMG/SKT group members

  • DPI


Low surface energy pu film with small contact angle hysteresis

THANK YOU FOR Hysteresis

YOUR ATTENTION