Shape Memory Polymers: Fundamentals, Advances and Applications Jinlian Hu SMITHERS R A P R A A Smithers Group Company Shawbury, Shrewsbury, Shropshire, SY4 4NR, United Kingdom Telephone: +44 (0)1939 250383 Fax: +44 (0)1939 251118 http://www.polymer-books.com
ontents Shape-memory Polymers 1 1.1 Introduction 1 1.2 Shape-memory Effect 4 1.2.1 Shape-memory Effect in Shape-memory Polymers 5 1.2.2 Shape-memory Effect in Shape-memory Polymers and Shape-memory Alloys 7 1.3 Structure of Shape-memory Polymers 9 1.3.1 Thermally Induced Shape-memory Polymers 10 1.3.2 Athermal Shape-memory Polymers 13 1.4 Classification of Shape-memory Polymers 15 1.5 Conclusions 17 Shape-memory Polymers: Molecular Design, Shape-memory Functionality and Programming 23 2.1 Introduction 23 2.2 Molecular Design of Shape-memory Polymers 23 2.2.1 Thermally Sensitive Shape-memory Polymers 24 2.2.1.1 Shape-memory Polymers based on the Amorphous Phase 24 2.2.1.2 Shape-memory Polymers based on Semi-crystalline Phase 25 2.2.1.3 Shape-memory Polymers based on Liquid Crystalline Phase 26 2.2.2 Photosensitive Shape-memory Polymers 26 2.2.3 Other Molecular Architectures of Shape-memory Polymers 28 vii
Shape Memory Polymers: Fundamentals, Advances and Applications 2.3 Shape-memory Programming 30 2.3.1 Processing One-way Shape-memory Effects 30 2.3.1.1 Dual-shape Creation Process for One-way Dual-shape Shape-memory Effects 31 2.3.1.2 Programming for One-way Triple-shape Shape-memory Effects 33 2.3.2 Processing Two-way Shape-memory Effects 34 2.3.2.1 Programming for Two-way Dual-shape Shape-memory Effects 35 2.3.2.2 Programming for Two-way Triple-shape Shape-memory Effects 35 2.3.3 Multiple Shape-memory Effects Programming 38 2.4 Shape-memory Functionality 38 2.4.1 One-way Shape-memory Effects 38 2.4.2 Two-way Shape-memory Effects 40 2.4.2.1 Liquid Crystalline Elastomers 41 2.4.2.2 Shape-memory Polymers having a Semi-crystalline Phase under Constant Stress 42 2.4.2.3 Shape-memory Polymer Laminated Composites 43 2.4.3 Triple/Multiple Shape-memory Effects 44 2.4.4 Temperature-memory Effects 48 2.5 Conclusions 48 3 Shape-memory Polymer Composites 57 3.1 Introduction 57 3.2 Nanowhisker/Shape-memory Polymer Composites 61 3.2.1 Cellulose Nanowhiskers 61 3.2.2 Integration of Cellulose Nanowhiskers 62 3.3 Carbon/Shape-memory Polymer Composites 65 3.3.1 Carbon Nanotube and Carbon Nanofibre/Shape-memory Polymer Composites 66
Contents 3.3.2 Carbon Black/Shape-memory Polymer Composites 67 3.3.3 Electrically Sensitive Shape-memory Polymer Nanocomposites 68 3.3.4 Light-sensitive Shape-memory Polymer Nanocomposites. 70 3.3.5 Enhanced General Shape-memory Effect 71 3.4 Fibre/Fabric-reinforced Shape-memory Polymer Composites 71 3.4.1 Microfibre or Fabric/Shape-memory Polymer Composites 71 3.4.2 Electrospun Nanofibre Shape-memory Polymer Nanocomposites 74 3.5 Metal and Metal Oxides/Shape-memory Polymer Composites 75 3.6 Other Shape-memory Polymer Composites 76 3.6.1 Nanoclay/Shape-memory Polymer Composites 76 3.6.2 Other Inorganic Filler/Shape-memory Polymer Composites 78 3.6.3 Organic Filler/Shape-memory Polymer Composites 78 3.6.4 Shape-memory Polymer Composites with Special Functions 79 3.7 Conclusions 81 4 Shape-memory Polymer Blends 89 4.1 Introduction 89 4.2 Miscible Polymer Blends 90 4.2.1 Shape-memory Polymer/Polymer Blends 90 4.2.2 Amorphous Polymer/Crystalline Polymer Blends 95 4.3 Immiscible Polymer Blends 97 4.3.1 Elastomer/Polymer Blends 97 4.3.2 Other Types of Immiscible Blends 100 4.4 Blending and Post-crosslinking Polymers Networks 106 4.4.1 Interpenetrating Polymer Networks 106 4.4.2 Crosslinked Polymer Blends 108 4.5 Conclusions 112 ix
Shape Memory Polymers: Fundamentals, Advances and Applications 5 Shape-memory Polymers Sensitive to Different Stimuli 117 5.1 Introduction 117 5.2 Thermally sensitive Shape-memory Polymers 117 5.2.1 Shape-memory Effect based on Conventional Glass or Melting Transition 118 5.2.2 Shape-memory Effect by Indirect Heating 120 5.2.3 Shape-memory Effect based on a Thermally Reversible Reaction 122 5.2.4 Shape-memory Effect based on Supermolecular Structure 123 5.2.5 Two-way Shape-memory Effect based on Change in the Conformation of Anisotropic Chains 125 5.2.6 Two-way Shape-memory Effect based on Coolinginduced Crystallisation Elongation 126 5.2.7 Two-way Shape-memory Effect based on Shapememory Polymer/Carbon Nanotube Composites 127 5.2.8 Multiple Shape-memory Effect based on Combined Switches 128 5.2.9 Thermally active and ph-active Polymeric Hydrogels... 131 5.3 Light-sensitive Shape-memory Polymers 132 5.3.1 Photodeformability Induced by Photoisomerisation 132 5.3.2 Photodeformability induced by Photoreactive Molecules 134 5.3.3 Photoactive Effect from the Addition-fragmentation Chain Transfer Reaction 134 5.3.4 Light-active Polymeric Hydrogels 136 5.4 Magnetic-sensitive Shape-memory Polymers 139 5.4.1 Shape-memory Polymer Matrices filled with Magnetic Particles 139 5.4.2 Magnetic-active polymeric gels 140 5.5 Water/solvent-sensitive Shape-memory Polymers 141 5.6 Electric-sensitive Shape-memory Polymers 144 5.7 Conclusions 148 x
Contents Modelling of Shape-memory Polymers 157 6.1 Introduction 157 6.2 Macroscale Constitutive Modelling 158 6.2.1 Stress-strain Characteristics 160 6.2.2 Shape-memory Properties 162 6.3 Mesoscale Modelling 166 6.4 Microscale Modelling 170 6.5 Molecular Dynamics and Monte Carlo Simulations 173 6.5.1 Reaction Characteristics 173 6.5.2 Physical Properties 173 6.5.3 Microstructure 174 6.5.4 Hydrogen bonding Interactions 176 6.5.5 Mechanical Properties 177 6.6 Mathematical Modelling 178 6.7 Modelling of Device Structures 178 6.8 Modelling for Light-sensitive Shape-memory Polymers 179 6.8.1 Three-dimensional Finite Deformation Modelling 179 6.8.2 Multiple Natural Configurations Modelling 181 6.8.3 Multi-scale Modelling 182 6.9 Conclusions 183 Supramolecular Shape-memory Polymers 189 7.1 Introduction 189 7.2 Supramolecular Chemistry 190 7.2.1 Hydrogen Bonding 192 7.2.2 Relationship between Shape-memory Polymers and Supramolecular Polymer Networks 192 7.3 Polymers Containing Pyridine Moieties: a Pathway to Achieve Supramolecular Networks 194 7.3.1 Function of Pyridine Moieties in Supramolecular Chemistry 194 XI
Shape Memory Polymers: Fundamentals, Advances and Applications 7.3.2 Supramolecular Pyridine-containing Polymers 195 7.3.3 Supramolecular Liquid Crystalline Polymer-containing Pyridine Moieties 196 7.4 Supramolecular Shape-memory Polymers based on Pyridine Moieties 197 7.4.1 Synthesis 197 7.4.2 Structure and Morphology 198 7.4.3 Thermally induced Shape-memory Effect 204 7.4.4 Moisture-sensitive Shape-memory Effect 206 7.5 Supramolecular Shape-memory Polymers based on Cyclodextrins 208 7.5.1 Cyclodextrins 208 7.5.2 Thermally induced Shape-memory Effect 209 7.5.3 Non-thermally Induced Shape-memory Effects 211 7.6 Potential Applications 215 7.6.1 Reshape Applications 215 7.6.2 Shape-memory Effect for Hairstyles in Beauty Care 215 7.6.3 Two-way Shape-memory Polymer Laminates 215 7.6.4 Medical Application: Antibacterial 216 7.6.5 Intelligent Windows for Smart Textile Applications 216 7.7 Conclusions 218 8 Applications of Shape-memory Polymers 223 8.1 Introduction 223 8.2 Applications of Bulk Shape-memory Polymers 223 8.2.1 Fixation 224 8.2.1.1 Orthodontic Wires 225 8.2.1.2 Medical Casts 226 8.2.2 Actuation 226 8.2.2.1 Actuation Realised by Combining Shapememory Polymers with Specific Structures 226 xn
Contents 8.2.2.2 Actuation arising from a Two-way Shapememory Effect 228 8.2.3 Deployment 228 8.2.3.1 Cold Hibernated Elastic Memory of Shapememory Polymer Foams 229 8.2.3.2 Expandable Stents 229 8.2.3.3 Deployable Dialysis Needles, Coils and Neuronal Electrodes 229 8.2.4 Self-healing 231 8.2.4.1 Confined Shape-recovery Self-healing 232 8.2.5 Fitting 233 8.3 Applications in Surface Wrinkling and Patterning 234 8.3.1 Principe of Surface Wrinkling 234 8.3.2 Wetting and Spreading 236 8.3.3 Adaptable Biological Devices for Modulating Cellularsubstrate Interactions 236 8.3.4 Biosensor and Micro-systems 238 8.3.5 Programmable Surface Pattern 239 8.3.6 No-programming Reversible Shape-memory Surface Patterns 239 8.4 Applications in Textiles 239 8.4.1 Shape-memory Polymer Fibres 239 8.4.2 Shape-memory Polymer Yarns and Fabrics 242 8.4.3 Shape-memory Polymer Solutions for Finishing Fabrics. 243 8.4.4 Shape-memory Polymer Nanofibres and their Nonwovens 245 8.4.5 Shape-memory Polymer Film/Foam and Laminated Textiles 247 8.5 Engineering Applications 249 8.5.1 Transportation 249 8.5.2 Sensors and Actuators 249 8.5.3 Filtration 251 xiii
Shape Memory Polymers: Fundamentals, Advances and Applications 8.5.4 Insulation 251 8.6 Conclusions 252 9 Future Outlook 261 9.1 Introduction 261 9.2 New Shape-memory Polymers with Novel Structures and Diversified Functionalities 261 9.2.1 New Stimulus Switches 262 9.2.2 Intrinsic Athermal Switches 262 9.2.3 Multi-responsive and Multi-functional Switches 263 9.3 Development Trends of Shape-memory Polymer Composites and Blends 263 9.3.1 Electric-Sensitive Shape-memory Effect 264 9.3.2 Light-Sensitive Shape-memory Effect 265 9.3.3 Magnetic-Sensitive Shape-memory Effect 265 9.3.4 Water/Solvent-Sensitive Shape-memory Effect 265 9.3.5 Shape-memory Effect based on Non-thermal Phase Transitions 266 9.4 Versatile Shape-memory Effects by Novel Programming Protocols 266 9.4.1 Programmability 266 9.4.2 Imperfection or a New Shape-memory Effect 267 9.5 Fundamental Understanding 268 9.6 Comprehensive Study of Structure-property Relationships 268 9.7 Modelling 269 9.8 Application in Textiles 269 9.9 Biomedical Applications 271 9.10 Applications toward Commercial Success 274 9.10.1 Maturing and Broadening of Applications 274 9.10.1.1 Existing Widely Researched Areas 274 9.10.1.2 Broadening Areas 275 xiv
Contents 9.10.1.3 Untouched Areas 275 9.10.2 Integrated Approaches 275 9.10.3 Challenging Issues in Applications 276 9.11 Supramolecular Shape-memory Polymers 277 9.12 Conclusions 279 Abbreviations 285 Index 295 xv