Responsive Polymer Surfaces

Adopting an integrated approach, this book covers experiments, theory, and emerging applications.
In the first part surfaces are described that change from flat to either a random corrugated or to a well-structured structure, while the second part deals with those surface structures integrated in the coating surface where the structures change their shape or dimension when addressed by an external trigger. A variety of materials are addressed, including liquid crystal polymers, hydrogels, hard acrylates, and soft silicones. The whole is rounded off by a discussion of various applications, including surface controlled flows in microfluidic systems.
Of interest to chemists and engineers, researchers in industry and academia, as well as those working in the paint industry and hydrodynamics.

Autorentext
Danqing Liu studied at the University of Electronic Science & Technology in Sichuan, China, where she received her bachelor's degree in 2006. In 2008, she received her master's degree in electronic engineering from Delft University of Technology, The Netherlands. Her Ph.D. study of responsive polymers was conducted at Eindhoven University of Technology, The Netherlands, where she graduated in 2013 and continued with a postdoctoral position with the focus on surface dynamics. Dr. Liu has around 20 publications in important peer reviewed journals and she is recipient of a Dutch national 4TU grant and Veni grant to proceed her research within the Netherlands.

Dirk J. Broer is a polymer chemist and specialized in polymer structuring and self-organizing polymer networks. He worked for more than 30 years at Philips Research in Eindhoven, The Netherlands. He was a senior research fellow and vice president at the Philips Research Laboratories specializing in biomedical devices and applications of polymeric materials. In parallel, he was appointed as part-time professor (1996) and as full professor (2010) at the Eindhoven University of Technology. He has authored more than 250 scientific publications and holds 120 patents. Furthermore, he is a member of the Royal Netherlands Academy of Arts and Sciences (KNAW).

Inhalt

List of Contributors xi

Preface xv

**1 Light-responsive Surface: Photodeformable Cross-linked Liquid-Crystalline Polymers Based on Photochemical Phase Transition 1
**Lang Qin and Yanlei Yu

1.1 Introduction 1

1.2 Photochemical Phase Transition 2

1.3 Photodeformation 3

1.3.1 Photoinduced Contraction and Expansion 3

1.3.2 Photoinduced Bending Movements 4

1.3.3 Photoinduced TwistingMovements 10

1.4 Effect Factors of Photodeformation 13

1.5 Deformation Induced by Visible and NIR Light 18

1.6 Soft Actuators Based on CLCPs 22

1.6.1 Macro-scaled Actuators 22

1.6.2 Micro-scaled Actuators 23

1.7 Summary 28

References 30

**2 Inkjet Printed Liquid Crystal Cilia 35
**Casper L. van Oosten, CeesW.M. Bastiaansen, and Dirk J. Broer

2.1 Introduction 35

2.2 Thermal Actuation Based on Anisotropic Thermal Expansion 37

2.3 Light Stimulated Deformation 41

2.4 Inkjet Printing Actuators: Toward Polymer Cilia 44

2.5 Conclusion 53

Acknowledgment 53

References 53

**3 Liquid Crystal Coatings Switched between Flat and Corrugated Surface Texture 57
**Danqing Liu and Dirk J. Broer

3.1 Introduction 57

3.2 Liquid Crystal Networks 58

3.3 Thermal-Responsiveness 60

3.4 Photo-Responsive Liquid Crystal Networks 61

3.5 Photo-Induced Surface Deformation 62

3.6 Photo-Induced Surface Deformation Preset by Patterned Director Orientation 66

3.7 Mechanism of Surface Deformation 73

3.8 Conclusions 79

References 79

**4 Computational Modeling of Light-triggered Topography Changes of Azobenzene-modified Liquid Crystal Polymer Coatings 85
**Ling Liu and Patrick R. Onck

4.1 Introduction 85

4.2 Photo-mechanical Model 88

4.2.1 Light PenetrationModel 88

4.2.2 Constitutive Equations 90

4.3 Results and Discussion 92

4.3.1 Light Penetration 93

4.3.2 Polydomain Coatings 94

4.3.3 Linearly Patterned Coatings 99

4.3.3.1 Effect of the In-plane Dimensions 101

4.3.3.2 Effect of Cholesteric Pitch Length 102

4.3.3.3 Effect of Transition Area 104

4.3.4 Fingerprint Coatings 105

4.3.5 Comparison and Discussion 110

4.4 Conclusions and Outlook 113

Acknowledgment 114

References 114

**5 Dynamic Tribology in Liquid Crystal Coatings 123
**Danqing Liu and Dirk J. Broer

5.1 Introduction 123

5.2 Dynamic Friction Analysis 124

5.2.1 Coating with a Fingerprint Texture 125

5.2.2 Coatings with a Polydomain Texture 126

5.2.3 Linear Protrusions 128

5.3 Static Friction Coefficients 132

5.4 Conclusions 133

References 134

**6 Actuating Hydrogel Thin Films 137
**Leonid Ionov

6.1 Introduction 137

6.2 Hydrogel Bilayer 138

6.3 Patterned Hydrogel Film 141

6.4 Bending of Complex Structures 142

6.5 Intrinsic Anisotropy 143

6.6 Applications of Hydrogel Actuators 145

6.6.1 Sensors 145

6.6.2 Smart Lenses 145

6.6.3 Imaging Devices 146

6.6.4 Switchable Coloration 146

6.6.5 Elements of Microfluidic Devices 147

6.6.6 Walkers and Swimmers 148

6.6.7 3D Microfabrication 150

6.6.8 Biomaterials 151

6.6.9 Stimuli-responsive Surfaces 151

6.7 Conclusions and Outlook 152

References 152

**7 Photoresponsive Polymer Hydrogel Coatings that Change Topography 159
**Jelle E. Stumpel, Jeroen ter Schiphorst, and Albertus P. H. J. Schenning

7.1 Introduction 159 7.2 Photoresponsive Polymer Hydrogel Coatings 160</p...