Physical gels from biological and synthetic polymers

Cover......Page 1
Contents......Page 7
Preface......Page 11
1.1 Gels from colloidal and polymer networks: a brief survey......Page 13
1.2 Structural characteristics and their study......Page 15
1.2.1 Solids versus liquids......Page 16
1.2.2 Multidisciplinary nature of gel studies......Page 17
1.3.1 Chemical gels......Page 18
1.3.2 Hybrid organic–inorganic materials......Page 19
1.4 Physical gels......Page 20
 Chapter 2 Techniques for the characterization of physical gels......Page 24
 Chapter 4 General properties of polymer networks......Page 25
 Chapter 7 Helical structures from neutral biopolymers......Page 26
 Chapter 9 Colloidal gels from proteins and peptides......Page 27
References......Page 28
2.2 Scattering techniques......Page 30
2.2.1 Principles of scattering......Page 31
2.2.2 Scattering by a single particle......Page 34
2.2.3 Effect of particle concentration......Page 35
2.2.4 Polymer solutions......Page 36
2.3 Calorimetric studies......Page 38
2.3.2 Differential scanning calorimetry (DSC)......Page 39
2.3.3 Microcalorimetry: µDSC......Page 42
2.3.4 Isothermal titration calorimetry (ITC)......Page 43
2.4.1 Transmission electron microscopy (TEM)......Page 45
2.4.2 Atomic force microscopy (AFM)......Page 49
2.5 Rheological characterization......Page 52
2.5.1.1 Small-deformation oscillatory shear methods......Page 53
2.5.1.2 Controlled strain versus controlled stress......Page 55
Polymer gels......Page 56
2.5.1.5 Temperature dependence......Page 57
The kinetic gelation experiment......Page 58
Gelation time measurement......Page 59
2.5.1.8 Failure of the Cox–Merz rule......Page 60
2.5.2 Large-deformation measurements......Page 61
2.6 Role of numerical simulations......Page 64
2.6.1 Fractal dimensions......Page 68
2.6.2 Gelling or non-gelling systems?......Page 70
2.6.3 Improvements of the interaction potentials......Page 72
References......Page 73
3.1 Flory–Stockmayer (‘classical’) theory......Page 76
3.2 Percolation model......Page 78
3.3 Percolation and phase transitions......Page 84
3.3.1 Extent of the critical domain......Page 86
3.4 Percolation and gelation......Page 87
3.4.1 Winter–Chambon criteria......Page 90
3.5.1 Percolation exponents......Page 92
3.5.2 Experimental determination by the Winter–Chambon criteria......Page 95
3.8 Zipper model......Page 102
3.9 Liquid crystal gels......Page 103
3.10 Conclusions......Page 105
References......Page 106
4 General properties of polymer networks......Page 109
4.1.1 Non-linear materials formed from the reaction of functional groups......Page 110
4.1.2 Non-linear materials from preformed polymer chains......Page 111
4.1.3 Poly(acrylamide) and poly(NIPAm) gels......Page 112
4.1.4 Copolymer networks......Page 113
4.2 Theories of rubber elasticity......Page 114
4.2.1 Reel chain models......Page 115
4.3 Swelling of gels......Page 116
4.3.1 Discontinuous swelling......Page 119
4.3.3 Smart gels......Page 120
4.4 Transient networks......Page 121
4.4.1 Model polymers with sticky end groups......Page 122
4.4.2.1 Elastic properties of the network of flowers (SJK model)......Page 127
4.4.2.2 Zero-shear viscosity (SJK model)......Page 129
4.4.2.3 Entangled sticky chains (LRC model)......Page 131
References......Page 134
 5.1 Introduction......Page 136
5.2 Molecular characteristics of polyelectrolytes......Page 137
5.3 Polyelectrolyte theories......Page 138
5.4 Gelation of carrageenans and gellans......Page 139
5.4.1 Effects of ions on structure formation......Page 144
5.4.2 Effects of cations on the transition temperature......Page 145
5.4.3 Role of monovalent cations......Page 147
5.4.4 Role of anions......Page 151
5.5.1 Alginates......Page 156
5.5.3 Egg-box type binding models......Page 159
5.6 Xanthan......Page 161
5.7 Chitin and chitosan......Page 163
References......Page 164
6.2.1 Origin of the hydrophobic effect......Page 168
6.3 Hydrophobically modified water-soluble polymers......Page 173
6.3.1 HM polyelectrolytes......Page 174
6.3.2 Polysaccharide derivatives with pendant alkyl side chains......Page 175
6.3.3 Random-block copolymers obtained by microemulsion polymerization......Page 177
6.3.4 Telechelic copolymers......Page 178
6.4 Rheology of associating polymers......Page 179
6.5 Interaction with surfactants......Page 182
6.6 Thermogelation or phase separation?......Page 185
References......Page 192
7.2 Gelatin......Page 194
7.2.2 Structure of native tropocollagen fibrils......Page 195
7.2.3 Amino acid composition in collagens from various sources: mammalian and fish......Page 196
7.2.5.1 Molecular mass distribution......Page 198
7.2.6 Gelation mechanism......Page 200
7.2.6.3 Parameters affecting helix formation......Page 202
7.2.6.4 Helix thermal stability......Page 205
7.2.6.5 Mechanisms of helical renaturation......Page 206
7.2.7.1 The sol–gel transition......Page 208
Concentration dependence of the shear modulus......Page 211
Source of gelatin......Page 213
7.2.8.1 Coil-like model......Page 214
7.2.8.2 Rod-like model......Page 215
7.2.9 Mechanical properties including high strains......Page 218
7.2.10 Phase diagram......Page 219
7.3 Agarose......Page 220
7.3.1 Gelation mechanism......Page 221
7.3.2 Phase behaviour......Page 223
7.3.3.1 Effect of concentration......Page 225
7.3.3.2 Effect of molecular mass......Page 226
7.3.3.5 Large-deformation behaviour of agarose gels......Page 227
7.3.4 Solvent effects......Page 228
7.4 Comparison between helical type networks......Page 229
7.5 Conclusions......Page 231
References......Page 232
8.1.1 Crystallization......Page 234
8.2 ‘Crystallization’-induced gelation: poly(vinylchloride) (PVC) gels......Page 235
8.2.1 Rheological measurements......Page 241
8.3.1 Atactic poly(styrene) in trans-decalin: phase separation and glass transition......Page 242
8.3.1.1 Morphology investigations......Page 244
8.3.2 Atactic poly(styrene) in carbon disulphide: gels induced by conformational changes......Page 245
8.3.2.1 Rheology of transparent gels......Page 249
8.4 Stereo-complexation and conformational changes: isotactic and syndiotactic PMMA gels......Page 251
8.4.1 Rheology of the stereo-complex gels......Page 254
8.4.2 The two-step mechanism in s-PMMA solutions......Page 255
8.5.1 Mechanisms of gel formation......Page 257
8.5.3 Drying and rehydration of cryogels......Page 261
8.6 Cryogels from polysaccharides......Page 263
8.7 Conclusions......Page 265
References......Page 266
 9.1 Introduction......Page 268
9.2.1 Structural aspects......Page 269
9.2.2 Rheological measurements......Page 273
9.3.1 Casein micelles......Page 277
9.3.2 Gelation kinetics......Page 278
9.3.4 Elastic modulus......Page 280
9.4.1 Amyloid gels......Page 281
9.4.2 Rheological measurements......Page 283
9.4.3 Phase behaviour......Page 287
9.5.1 Insulin and lysozyme gels......Page 289
9.5.2 G and F actin......Page 290
9.5.3 Tubulin......Page 291
9.5.5 ‘Amyloid’ protein gels formed in non-aqueous media......Page 292
9.5.6 Gels from peptide self-assembly......Page 293
References......Page 294
 10.1 Introduction......Page 299
10.2 Equilibrium thermodynamics......Page 301
10.3.1 Nucleation and growth......Page 302
10.3.2 Spinodal decomposition......Page 303
10.3.3 Kinetics of demixing......Page 305
10.3.4 Spinodal decomposition in polymer mixtures......Page 306
10.3.5 Spinodal decomposition of ternary systems......Page 307
10.3.6 Kinetics of demixing and gelation in ternary systems......Page 308
10.3.7 Rheology of mixed systems......Page 309
10.4.1 Protein–polysaccharide mixtures......Page 310
10.4.1.1 Gelatin–dextran......Page 311
10.4.1.2 Gelatin–maltodextrin......Page 312
10.4.1.3 Gelatin–agarose......Page 313
10.4.1.4 Casein–dextran......Page 315
10.4.3 Protein–protein mixed-gel systems......Page 316
10.4.4.1 Gellan and κ-carrageenan......Page 317
10.4.4.3 κ-carrageenan–agarose......Page 319
10.4.4.4 Starch: a mixture of amylose and amylopectin......Page 320
10.5 Filled gels......Page 321
10.6.1 Polysaccharide systems......Page 322
10.6.2 Polysaccharide mixed-gel interactions......Page 323
10.6.2.1 Molecular models for polysaccharide gel interactions......Page 324
10.6.2.2 ‘Synergistic’ mixed polysaccharide gels......Page 325
κ-carrageenan mixtures......Page 326
Gellan mixtures......Page 327
Xanthan mixtures......Page 330
Gels from other polysaccharide mixtures......Page 333
References......Page 334
11.1.1 Slide-ring gels......Page 338
11.1.2 Polyelectrolyte complexes......Page 339
11.1.3 Gel micro- and nanoparticles......Page 341
11.1.4 Multi-membrane hydrogels......Page 343
11.1.5 Hydrogels as ultra-sensitive sensors......Page 345
11.2 Food and cosmetic applications......Page 346
11.3.1 Applications of chitosan......Page 348
11.3.1.2 Grafted chitosan hydrogels......Page 349
11.3.1.3 Chitosan–PVA complexes......Page 350
11.3.2.1 Inhomogeneous alginate beads......Page 351
11.3.2.2 Beads with hierarchical macroporosity......Page 352
11.3.2.3 Amphiphilic alginate beads......Page 354
11.3.3 Nanoparticles for protein delivery: production, assembly and structure......Page 356
11.3.5.1 Harmonized foaming and gelation......Page 358
11.3.6 Superdisintegrant materials......Page 360
11.3.7 Further applications in tissue engineering......Page 361
References......Page 363
Index......Page 365