Cyclodextrins

SAHAR AMIRI currently works at the Department of Polymer Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran. Her research interests include synthesis and characterization of polymers, including silicone-based polymers and copolymers, cobalt-mediated radical polymerization (CMRP), inclusion complex between Cyclodextrins and various polymers and nano-capsule synthesis based on cyclodextrins. She has authored 2 books and more than 35 papers to date. SANAM AMIRI works at Department of Textile Engineering, Amirkabir University of Technology, Tehran, Iran. Her current research interests include synthesis of polymers including silicone-based polymers and copolymers, cobalt-mediated radical polymerization (CMRP) and using Cyclodextrins in textile engineering and thermos-reversible lock copolymers based on Cyclodextrins.

Preface xv

1 Introduction 1

1.1 History of Cyclodextrins 2

1.2 Cyclodextrin Properties 3

1.2.1 Toxicity Considerations 5

1.2.2 Inclusion Complex Formation 6

1.3 Inclusion Complex Formation Mechanism 8

1.3.1 Hydrophobic Interaction 10

1.3.2 van derWaals Interaction 11

1.3.3 Hydrogen-Bonding Interaction 11

1.3.4 Release of Enthalpy-RichWater 11

1.3.5 Release of Conformational Strain 12

1.3.6 Inclusion Complex Formation with Various Environments 12

1.4 Important Parameters in Inclusion Complex Formation 15

1.4.1 Effects of Temperature 15

1.4.2 Use of Solvents 16

1.4.3 Effects ofWater 16

1.4.4 Solution Dynamics 16

1.4.5 Volatile Guests 17

1.5 Inclusion Complex Formation Methods 17

1.5.1 Coprecipitation 17

1.5.2 Slurry Complex Formation 18

1.5.3 Paste Complexation 18

1.5.4 Wet Mixing and Heating 18

1.5.5 Extrusion 18

1.5.6 Dry Mixing 18

1.6 Methods for Drying of Complexes 19

1.6.1 Highly Volatile Guests 19

1.6.2 Spray Drying 19

1.6.3 Low-Temperature Drying 19

1.7 Release of the Complex 19

1.8 Application of Inclusion Compounds 20

1.8.1 Characterization of Inclusion Complexes 20

1.9 Applications of Cyclodextrins 21

1.9.1 Cosmetics, Personal Care, and Make Up 22

1.9.2 Foods and Flavors 22

1.9.3 Pharmaceuticals 23

1.9.3.1 Drug Delivery 24

1.9.3.2 Gene Delivery 26

1.9.4 Cyclodextrin Applications in Agricultural and Chemical Industries 27

1.9.5 Encapsulation of Various Guest Molecules 28

1.9.6 Supramolecular Polymer Base on Host–Guest Complexes 29

1.10 Characterization and Experimental Techniques 29

1.10.1 NMR Spectroscopy 30

1.10.2 FTIR Spectroscopy 30

1.10.3 X-ray Diffraction 30

1.10.4 Thermogravimetric Analysis 30

1.10.5 UV–Vis Spectral Changes 31

1.10.6 Phase Solubility Technique 31

References 31

2 Supramolecular Chemistry and Rotaxane 41

2.1 What Is Supramolecular Chemistry 41

2.1.1 History of Supramolecular Chemistry 42

2.1.2 Concept of Supramolecular Chemistry 43

2.1.2.1 Noncovalent Interactions 43

2.1.2.2 Electrostatic Interactions 44

2.1.2.3 Hydrogen Bonding 44

2.1.2.4 Van derWaals Interactions 46

2.1.2.5 Hydrophobic Effect 47

2.2 Host–Guest Chemistry 47

2.2.1 Cyclodextrins as Supramolecular Hosts 48

2.3 Cyclodextrin-Containing Supramolecular Structures 48

2.3.1 Cyclodextrins 49

2.3.2 Cyclodextrin Shape and Inclusion Complex Formation 49

2.4 Supramolecular Chemistry 49

2.4.1 Cyclodextrin Rotaxanes 50

2.4.2 Studies on Responsive CD-Based Polymers 52

2.4.2.1 Cyclodextrin Dimers 52

2.4.2.2 Catenanes 52

2.4.2.3 Rotaxanes 53

2.5 Cyclodextrin-based Rotaxanes and Pseudorotaxanes 54

2.5.1 Pseudopolyrotaxanes 57

2.5.1.1 Synthetic Route 58

2.5.2 Polyrotaxanes and Pseudopolyrotaxanes Based on Cyclodextrins 58

2.5.3 Cyclodextrin-based Polyrotaxanes 60

2.5.4 Cyclodextrin Molecular Tubes 62

2.5.4.1 Cyclodextrin-Based Nanotube Structure 63

References 65

3 Smart Polymers 75

3.1 Introduction 75

3.2 Supramolecular Self-Assembly 76

3.3 Synthesis of Block Copolymers 76

3.3.1 Free and Living Radical Polymerization 76

3.3.2 Block Copolymers 79

3.4 Self-Assembly of Amphiphilic Block Copolymers 79

3.4.1 Smart Polymers Synthesized Based on Living Controlled Radical Polymerization 81

3.4.2 Definition of Self-Assembly 82

3.4.3 Self-Assembled Structures Based on Block Copolymers 83

3.4.3.1 Micelles 84

3.4.3.2 Vesicles 84

3.4.3.3 Dendrons and Dendrimers 86

3.5 Stimuli-Sensitive Supramolecular Structures 87

3.5.1 Stimuli-Responsive Polymers Based on Cyclodextrins 89

3.5.2 pH-Responsive Systems 90

3.5.3 Temperature-Responsive Systems 93

3.5.4 Redox-Responsive Systems 96

3.5.5 Other Stimuli-Responsive Hydrogels 96

3.5.5.1 Light-SensitiveMaterials 96

3.5.5.2 Photoresponsive Polymers 97

3.5.5.3 Photoresponsive Liposomes 97

3.5.5.4 Photoresponsive Micelles 97

3.5.5.5 Photoresponsive Vesicles 99

3.5.5.6 Electroresponsive Polymers 100

3.5.5.7 Magnetic-Responsive Polymers 102

3.6 Polymers with Dual-Stimuli Responsiveness 103

3.6.1 Cyclodextrins for Synthesis of Responsive Supramolecules 104

3.6.2 pH-Responsive Inclusion Complexes 104

3.6.3 Temperature-Responsive Inclusion Complexes 107

3.6.4 Photoresponsive Inclusion Complexes 109

3.6.5 pH-Sensitive Polyrotaxane 110

3.7 Stimuli-Sensitive Polyrotaxane for Drug Delivery 111

3.7.1 Photoresponsive Inclusion Complex Application 113

3.7.2 Redox-Responsive Inclusion Complexes Applications 117

3.8 Multi-Stimuli-Responsive Inclusion Complexes 120

3.8.1 pH- and Temperature-Responsive Inclusion Complexes Applications 120

3.8.2 pH- and Redox-Responsive Inclusion Complexes Applications 121

3.8.3 Temperature- and Photoresponsive Inclusion Complexes Applications 121

3.8.4 Temperature- and Redox-Responsive Inclusion Complexes Applications 123

References 124

4 Basics of Corrosion 141

4.1 Introduction to Corrosion and Its Types 142

4.1.1 Corrosion 142

4.1.2 Forms of Corrosion 143

4.1.2.1 Uniform Corrosion 143

4.1.2.2 Galvanic Corrosion 144

4.1.2.3 Pitting Corrosion 145

4.1.2.4 Crevice Corrosion 146

4.1.2.5 Intergranular Corrosion (IGC) 147

4.1.2.6 Dealloying Corrosion 147

4.1.2.7 Stress Corrosion Cracking (SCC) 148

4.1.2.8 Erosion Corrosion 149

4.2 Corrosion Protection 149

4.2.1 Anticorrosion Methods 149

4.2.2 Anticorrosion Coating 150

4.3 An Introduction to Self-healing Coatings 151

4.3.1 Classification of Self-healing Approaches 152

4.3.1.1 Materials with Intrinsic Self-healing 152

4.3.1.2 Capsule-based Sealing Approach 154

4.3.1.3 Vascular Self-healingMaterials 157

4.3.1.4 Active Anticorrosion Coatings 158

4.4 Protective Coatings Containing Corrosion Inhibitors 160

4.5 An Introduction to Sol–Gel 160

4.5.1 Sol–Gel Chemistry 161

4.5.2 General Procedures Involved in the Preparation of Sol–Gel Coatings 162

4.5.3 Applications of Sol–Gel-Derived Coating 163

4.5.3.1 Corrosion Protective Sol–Gel Coatings 163

4.5.3.2 Organic–Inorganic Hybrid (OIH) Sol–Gel Coatings 164

4.6 Addition of Corrosion Inhibitors to Sol–Gel Coating Micro-/Nanoparticles 166

4.6.1 Direct Addition of Inhibitor 166

4.6.1.1 Inorganic Inhibitors 166

4.7 Self-healing Coating Containing Corrosion Inhibitor Capsules 168

4.7.1 Self-healing Anticorrosion Coatings Based on Nano-/Microcontainers Loaded with Corrosion Inhibitors 168

4.7.2 Preparation of Supramolecular Corrosion Inhibitor Nanocontainers for Self-protective Hybrid Nanocomposite Coatings 169

4.7.2.1 Formation of Cyclodextrin–Inhibitor Inclusion Complexes 171

4.7.2.2 Characterization of Encapsulated Organic Corrosion Inhibitors 172

4.8 Morphology of the Smart Corrosion Inhibitor Nanocontainers 178

4.8.1 Microstructural Characterization 180

4.8.2 Self-healingMechanism of Corrosion Inhibitor Nanocontainers 181

4.8.3 EIS Measurement of Coating Containing Inhibitor Nanocontainers 182

4.8.4 Salt Spray Test for Investigation of Anticorrosive Performance of the Nanocapsules Incorporated Coating 185

4.8.5 Controlled Release of Inhibitors from Nanocontainers Obtained by Encapsulation of Inhibitor Corrosion in CDs 187

4.9 Concluding Remarks 188

References 189

5 Phytochemicals 201

5.1 Phenolic Acids 202

5.1.1 Polyphenolic Antioxidant Property 204

5.1.2 Phenolic Compounds and Free Radicals 204

5.1.3 Extraction of Plant Polyphenols 205

5.2 Flavanoids 206

5.2.1 Flavones 207

5.2.2 Catechins 207

5.2.3 Isoflavonoids 208

5.2.4 Tannins 208

5.2.5 Anthocyanidins 208

5.2.6 Lignans and Stilbenes 208

5.2.7 Alkaloids and Other Nitrogen-containing Metabolites 209

5.3 Phytochemical Importance 209

5.3.1 Oxidative Stress and Phenolic Compounds in Foods 209

5.3.2 Important Parameters for Phenolic Efficiency 210

5.4 Encapsulation 211

5.4.1 Polyphenol Encapsulation 212

5.4.2 Physical Methods 213

5.4.2.1 Spray-drying 214

5.4.2.2 Fluid Bed Coating 214

5.4.2.3 Extrusion–Spheronization Technique 215

5.4.2.4 Centrifugal Extrusion 215

5.4.2.5 Supercritical Fluids 215

5.4.3 Physicochemical Methods 216

5.4.3.1 Spray-cooling/Chilling 216

5.4.3.2 Encapsulation by Emulsions 216

5.4.3.3 Coacervation 217

5.4.3.4 Ultrasonication 217

5.4.4 Chemical Methods 218

5.4.4.1 Micelles 218

5.4.4.2 Liposomes 219

5.4.4.3 In Situ Polymerization 220

5.4.4.4 Interfacial Polymerization 221

5.4.4.5 Freeze-drying 221

5.5 Encapsulation of Phenolic Compounds Via Cyclodextrin 222

5.5.1 Cyclodextrin Inclusion Complexes Formation 223

5.5.2 Polyphenol Encapsulation in Cyclodextrins 223

5.5.3 Solubilization and Stabilization of Polyphenols 224

5.6 Why Encapsulation by Cyclodextrin? 224

5.6.1 Cyclodextrins and Flavonoids 225

5.7 Concluding Remarks 227

References 227

6 Cyclodextrins Application as Macroinitiator 239

6.1 Cyclodextrins Application as Macroinitiator in Polyrotaxane Synthesis Via ATRP 239

6.2 Inclusion Complexes of PDMS and γ-CDWithout Utilizing Sonic Energy 241

6.3 Supramolecular Pentablock Copolymer Containing Via ATRP of Styrene and Vinyl Acetate Based on PDMS/CD Inclusion Complexes as Macroinitiator 246

6.3.1 Complex Formation of γ-CD with Br–PDMS–Br 248

6.3.2 Characterization of Polyrotaxane-based Pentablock Copolymers 249

6.4 Synthesis and Characterization of Poly(vinylacetate)-b- Polystyrene-b-(Polydimethyl siloxane/cyclodextrin)-b-Polystyrene-b-Poly(vinyl acetate) Pentablock Copolymers 256

6.4.1 Preparation of PDMS Macroinitiator (Br–PDMS–Br) 258

6.4.2 Polymerization of St and PVAc Initiated by PDMS–CDs Macroinitiator 259

6.4.3 Microstructural Studies of the Pentablock Copolymers 263

6.5 Conclusion 265

References 265

7 Cyclodextrin Applications 269

7.1 Cyclodextrin Industrial Applications 269

7.1.1 Pharmaceutical Applications of Cyclodextrins 270

7.1.2 Inclusion Complex Formation Advantages with Drugs 271

7.1.2.1 Water Solubility 271

7.1.2.2 Drug Bioavailability 271

7.1.2.3 Drug Safety 271

7.1.2.4 Drug Stability 272

7.1.2.5 Mask Unpleasant Odor, Taste, and Side Effects of Drugs 272

7.1.2.6 Drug Stability 272

7.1.2.7 Drug Solubility and Dissolution 273

7.1.2.8 Reduction in Volatility 273

7.1.3 CD-based Carriers 273

7.2 Drug Delivery Systems Based on Cyclodextrins 273

7.2.1 Oral Drug Delivery System 274

7.2.2 Rectal Drug Delivery System 274

7.2.3 Nasal Drug Delivery System 275

7.2.4 Transdermal Drug Delivery System 275

7.2.5 Ocular Drug Delivery System 275

7.2.6 Liposomal Drug Delivery 276

7.2.7 Osmotic Pump Tablet 277

7.2.8 Peptide and Protein Delivery 277

7.3 Cyclodextrin-based Targeting Systems 278

7.3.1 Nanoparticles 279

7.3.2 Nanocapsules 279

7.3.3 Microsphere 280

7.3.4 Nanosponges 280

7.4 CDs in the Food Industry 281

7.5 Cyclodextrins in Skin Delivery and Cosmetic 283

7.6 Agricultural Applications 284

7.7 Self-healing Coating 285

References 287

Index 301