Mechanically Responsive Materials for Soft Robotics offers an authoritative guide to the current state of mechanically responsive materials for the development of soft robotics. With contributions from an international panel of experts, the book examines existing mechanically responsive materials such as crystals, polymers, gels, and composites that are stimulated by light and heat. The book also explores the application of mechanical materials to soft robotics. The authors describe the many excellent mechanical crystals developed in recent years that show the ability to bend, twist, rotate, jump, self-heal, and shape memory. Mechanical polymer materials are described for evolution into artificial muscles, photomobile materials, bioinspired soft actuators, inorganic-organic hybrid materials, multi-responsive composite materials, and strain sensor materials.
The application of mechanical materials to soft robots is just the beginning. This book reviews the many challenging and versatile applications, such as soft microrobots made from photoresponsive elastomers, four-dimensional printing for assembling soft robots, self-growing of soft robots like plants, and biohybrid robots using muscle tissue. This important book:
-Explores recent developments in the use of soft smart materials in robotic systems
-Covers the full scope of mechanically responsive materials: polymers, crystals, gels, and nanocomposites
-Deals with an interdisciplinary topic of advanced smart materials research
-Contains extensive descriptions of current and future applications in soft robotics
Written for materials scientists, polymer chemists, photochemists, physical chemists, solid state chemists, inorganic chemists, and robotics engineers, Mechanically Responsive Materials for Soft Robotics offers a comprehensive and timely review of the most recent research on mechanically responsive materials and the manufacture of soft robotics.
Table of Contents
Preface xiii
Part I Mechanically Responsive Crystals 1
1 Photomechanical Behavior of Photochromic Diarylethene Crystals 3
Seiya Kobatake and Daichi Kitagawa
1.1 Introduction 3
1.2 Crystal Deformation Exhibiting Expansion/Contraction upon Photoirradiation 6
1.3 Photoresponsive Bending 7
1.4 Dependence of Bending Behavior on Irradiation Wavelength 11
1.5 Photomechanical Work of Diarylethene Crystals That Exhibit Bending 13
1.6 New Types of Photomechanical Motion 15
1.7 Photosalient Effect 20
1.8 Summary 22
References 23
2 Photomechanical Crystals Made from Anthracene Derivatives 29
Fei Tong, Christopher J. Bardeen, and Rabih O. Al-Kaysi
2.1 Introduction 29
2.2 Elements of Photomechanical Molecular Crystals 30
2.3 The Advantage of Using Anthracene Derivatives in Photomechanical Crystals 33
2.4 Types of Anthracene Photomechanical Crystals 34
2.4.1 NR-Type Anthracene Derivatives 34
2.4.1.1 9-Anthracene Carboxylate Ester Derivatives 34
2.4.1.2 9-Methylanthracene 36
2.4.1.3 9-Cyanoanthracne, 9-Anthealdehyde, and 9,10-Dinitroanthracene 37
2.4.1.4 Conjugated Anthracene Derivatives with Trans-to-Cis Photochemistry 38
2.4.2 T-Type Photomechanical Crystals Based on Reversible 4π+4π Photodimerization 39
2.4.3 P-Type Anthracene Derivatives 44
2.5 Synthesis of Anthracene Derivatives 46
2.6 Future Direction and Outlook 47
2.6.1 Modeling Reaction Dynamics in Molecular Crystals 47
2.6.2 New Anthracene Derivatives and Crystal Shapes 48
2.6.3 Interfacing Photomechanical Molecular Crystals with Other Materials 49
2.7 Conclusion 50
Acknowledgments 50
References 50
3 Mechanically Responsive Crystals by Light and Heat 57
Hideko Koshima, Takuya Taniguchi, and Toru Asahi
3.1 Introduction 57
3.2 Photomechanical Bending of Crystals by Photoreactions 59
3.2.1 Azobenzene 59
3.2.1.1 Bending 59
3.2.1.2 Twisted Bending 61
3.2.2 Salicylideneaniline and Analogues 61
3.2.2.1 Bending and the Mechanism 63
3.2.2.2 Comparison of Chiral and Racemic Crystals 64
3.2.3 Fulgide 64
3.2.4 Carbonyl Compounds 66
3.3 Locomotion of Crystals by Thermal Phase Transition 67
3.3.1 Inchworm-Like Walking 70
3.3.2 Fast Rolling Locomotion 71
3.4 Diversification of Mechanical Motion by Photo-triggered Phase Transition 72
3.4.1 Discovery and the Mechanism of Photo-triggered Phase Transition 72
3.4.2 Stepwise Bending 75
3.5 Why Crystals? 75
3.6 Summary and Outlook 77
References 77
4 Crawling Motion of Crystals on Solid Surfaces by Photo-induced Reversible Crystal-to-Melt Phase Transition 83
Yasuo Norikane and Koichiro Saito
4.1 Introduction 83
4.2 Isomerization of Azobenzene 84
4.3 Phase Transitions in Liquid Crystals (Liquid-Crystal-to-Isotropic) 86
4.4 Phase Transitions in Crystal Phase (Crystal-to-Melt) 87
4.4.1 Characteristics of the Crystal-to-Melt Phase Transition 87
4.4.2 Potential Applications of Crystal-to-Melt Transition 89
4.4.3 Mechanical Motions Derived from the Crystal-to-Liquid Phase Transition 92
4.5 Photo-induced Crawling Motion of Azobenzene Crystals 94
4.5.1 Discovery of the Crawling Motion of Crystal on Solid Surface 94
4.5.2 Characteristics of the Crawling Motion of Crystals 95
4.5.3 Mechanism of the Crawling Motion 98
4.5.4 Crawling Motion of Azobenzene Crystals 98
4.6 Conclusion 98
References 99
5 Bending, Jumping, and Self-Healing Crystals 105
Panĉe Naumov, Stanislav Chizhik, Patrick Commins, and Elena Boldyreva
5.1 Bending Crystals 105
5.1.1 General Mechanism of Crystal Bending 105
5.1.2 Kinetic Model of the Transformation 108
5.1.3 Mechanical Response of a Crystal to Irradiation 112
5.1.4 A Case Study, Linkage Isomerization of [Co(NH3)5NO2]Cl(NO3) 116
5.1.5 Concluding Remarks 117
5.2 Salient Crystals 118
5.2.1 Salient Effects 118
5.2.2 Mechanism of the Thermosalient Transition 120
5.2.3 Thermal Signature of the Thermosalient Effect 123
5.2.4 Directionality of Motion 124
5.2.5 Effect of Intermolecular Interactions 125
5.2.6 Effect of Crystal Habit 127
5.2.7 Photosalient and Mechanosalient Effects 128
5.2.8 Applications of the Salient Effects 130
5.3 Self-healing Crystals 131
References 133
6 Shape Memory Molecular Crystals 139
Satoshi Takamizawa
Introduction 139
6.1 Discovery of Organosuperelasticity 141
6.2 Twinning Organosuperelasticity 149
6.3 Organosuperplasticity Through Multilayered Sliding 156
6.4 Twinning Ferroelasticity 158
6.5 Summary 173
References 173
Part II Mechanically Responsive Polymers and Composites 177
7 Mechanical Polymeric Materials Based on Cyclodextrins as Artificial Muscles 179
Akira Harada, Yoshinori Takashima, Akihito Hashidzume, and Hiroyasu Yamaguchi
7.1 Introduction 179
7.2 Artificial Muscle Regulated by Cross-Linking Density 180
7.2.1 A Host-Guest Gel with αCD and Azo 180
7.2.2 Photo-Responsive Volume Change of αCD-Azo Gels 181
7.2.3 Photo-Responsive Property of αCD-Azo Gels 184
7.3 Artificial Muscle Regulated by Sliding Motion 187
7.3.1 Preparation of a Topological Hydrogel (αCD-Azo Hydrogel) 188
7.3.2 Mechanical and Photo-Responsive Properties of the αCD-Azo Hydrogel 188
7.3.3 UV and Vis Light-Responsive Actuation of the αCD-Azo Xerogel 192
7.4 An Artificial Molecular Actuator with a [c2]Daisy Chain ([c2]AzoCD2) 192
7.4.1 Photo-Responsive Actuation of the [c2]AzoCD2 Hydrogel 194
7.4.2 Photo-Responsive Actuation of the [c2]AzoCD2 Xerogel 196
7.5 Supramolecular Materials Consisting of CD and Sti 199
7.5.1 (αCD-Sti)2 Hydrogel 199
7.5.2 (αCD-Sti)2 Dry Gel 202
7.6 Concluding Remarks 204
References 205
8 Cross-Linked Liquid-Crystalline Polymers as Photomobile Materials 209
Toru Ube and Tomiki Ikeda
Introduction 209
8.1 Structures and Functions of Photomobile Materials Based on LCPs 211
8.1.1 Polysiloxanes 211
8.1.2 Polyacrylates 213
8.1.3 Polyacrylate Elastomers Prepared from LC Macromers 218
8.1.4 Systems with Multiple Polymer Components 218
8.1.5 Composites 220
8.1.6 Linear Polymers 222
8.1.7 Rearrangeable Network with Dynamic Covalent Bonds 224
8.2 Summary 226
References 226
9 Photomechanical Liquid Crystal Polymers and Bioinspired Soft Actuators 233
Chongyu Zhu, Lang Qin, Yao Lu, Jiahao Sun, and Yanlei Yu
9.1 Background 233
9.2 Actuation Principles 234
9.2.1 Photochemical Phase Transition 235
9.2.2 Weigert Effect 237
9.2.3 Photothermal Effect 239
9.3 Bioinspired Actuators and Their Applications 242
9.3.1 Soft Actuators Driven by Photothermal Effect 243
9.3.2 Photoinduced Actuation of Soft Actuators 245
9.4 Conclusion 251
References 253
10 Organic-Inorganic Hybrid Materials with Photomechanical Functions 257
Sufang Guo and Atsushi Shimojima
10.1 Introduction 257
10.2 Azobenzene as Organic Components 258
10.3 Siloxane-Based Organic-Inorganic Hybrids 258
10.4 Photoresponsive Azobenzene-Siloxane Hybrid Materials 261
10.4.1 Nanostructural Control by Self-Assembly Processes 261
10.4.2 Lamellar Siloxane-Based Hybrids with Pendant Azobenzene Groups 262
10.4.3 Lamellar Siloxane-Based Hybrids with Bridging Azobenzene Groups 264
10.4.4 Photo-Induced Bending of Azobenzene-Siloxane Hybrid Film 265
10.4.5 Control of the Arrangement of Azobenzene Groups 268
10.5 Other Azobenzene-Inorganic Hybrids 270
10.5.1 Intercalation Compounds 270
10.5.2 Hybridization with Carbon-Based Materials 270
10.6 Summary and Outlook 272
References 272
11 Multi-responsive Polymer Actuators by Thermo-reversible Chemistry 277
Antoniya Toncheva, Loïc Blanc, Pierre Lambert, Philippe Dubois, and Jean-Marie Raquez
11.1 Introduction 277
11.2 Covalent Adaptive Networks 279
11.2.1 Associative CANs 279
11.2.2 Dissociative CANs 280
11.3 Thermo-reversible Chemistry 280
11.4 DA Reactions for Thermo-reversible Networks 282
11.4.1 Basic Definitions 282
11.4.2 DA Reactions for Polymer Synthesis 282
11.4.3 DA Reactions for Thermo-reversible Polymer Network 283
11.4.3.1 Self-healing Materials 283
11.4.3.2 Hydrogels 287
11.5 Soft Actuators 289
11.6 DA-based SMPs for Soft Robotics Application 292
11.7 On the Road to 3D Printing 293
11.8 Perspectives and Challenges 295
Acknowledgments 298
References 298
12 Mechanochromic Polymers as Stress-sensing Soft Materials 307
Daisuke Aoki and Hideyuki Otsuka
12.1 Introduction 307
12.2 Classification of Mechanochromic Polymers 307
12.3 Mechanochromophores Based on Dynamic Covalent Chemistry 309
12.4 Mechanochromic Polymers Based on Dynamic Covalent Chemistry 310
12.4.1 Polystyrenes with Mechanochromophores at the Center of the Polymer Chain 310
12.4.2 Polyurethane Elastomers with Mechanophores in the Repeating Units 310
12.4.3 Mechanochromic Elastomers Based on Polymer-Inorganic Composites with Dynamic Covalent Mechanochromophores 312
12.5 Mechanochromic Polymers Exhibiting Mechanofluorescence 315
12.6 Rainbow Mechanochromism Based onThree Radical-type Mechanochromophores 316
12.7 Multicolor Mechanochromism Based on Radical-type Mechanochromophores 318
12.8 Foresight 321
References 323
Part III Application of Mechanically Responsive Materials to Soft Robots 327
13 Soft Microrobots Based on Photoresponsive Materials 329
Stefano Palagi
13.1 Soft Robotics at the Micro Scale 329
13.2 LCEs for Microrobotics 330
13.2.1 Thermal Response of LCEs 330
13.2.2 Photothermal Actuation of LCEs 331
13.3 Light-Controlled Soft Microrobots 335
13.3.1 Structured Light 337
13.3.2 Controlled Actuation 338
13.3.2.1 Role of Control Parameters 338
13.3.3 Swimming Microrobots 341
13.4 Outlook 344
References 344
14 4D Printing: An Enabling Technology for Soft Robotics 347
Carlos Sánchez-Somolinos
14.1 Introduction 347
14.2 3D Printing Techniques 348
14.2.1 Material Extrusion-Based Techniques 349
14.2.2 Vat Photopolymerization Techniques 350
14.3 4D Printing of Responsive Materials 352
14.3.1 Shape Memory Polymers 352
14.3.2 Hydrogels 355
14.3.3 Liquid Crystalline Elastomers 356
14.4 4D Printing Toward Soft Robotics 358
14.5 Conclusions 359
Acknowledgments 360
References 360
15 Self-growing Adaptable Soft Robots 363
Barbara Mazzolai, Alessio Mondini, Emanuela Del Dottore, and Ali Sadeghi
15.1 Introduction 363
15.2 Evolution of Growing Robots 365
15.3 Mechanisms for Adaptive Growth in Plants 367
15.4 Plant-Inspired Growing Mechanisms for Robotics 369
15.4.1 Challenges in Underground Exploration 369
15.4.2 The “Evolution” of Plantoids 369
15.4.3 Sloughing Mechanism 371
15.4.4 First Growing Mechanism 371
15.4.5 Artificial Roots with Soft Spring-Based Actuators 373
15.4.6 Growing Robots via Embedded 3D Printing 375
15.4.6.1 Deposition Strategies 376
15.5 Adaptive Strategies in Plant for Robot Behavior 379
15.5.1 A Plant-Inspired Kinematics Model 380
15.5.2 Plant-Inspired Behavioral Control 382
15.5.3 Circumnutation Movements in Natural and Artificial Roots 385
15.6 Applications and Perspective 387
Acknowledgments 388
References 388
16 Biohybrid Robot Powered by Muscle Tissues 395
Yuya Morimoto and Shoji Takeuchi
16.1 Introduction 395
16.2 Muscle Usable in Biohybrid Robots 396
16.2.1 Cardiomyocyte and Cardiac Muscle Tissue 397
16.2.2 Skeletal Muscle Fiber and Skeletal Muscle Tissue 398
16.2.3 Cell and Tissue Other Than Mammals 399
16.3 Actuation of Biohybrid Robots Powered by Muscle 400
16.3.1 Biohybrid Robot with a Single Muscle Cell 401
16.3.2 Biohybrid Robot with Monolayer of Muscle Cells 402
16.3.3 Biohybrid Robot with Muscle Tissues 406
16.4 Summary and Future Directions 410
References 411
Index 417
