Molecular Dynamics of Glass-Forming Systems (eBook)

Preface 8
Contents 12
Chapter 1: The Glass ``Transition´´ 14
1.1 Introduction 14
1.2 Pressure Dependence of the Structural (a-) Relaxation Time 18
1.3 The Glass Transition Temperature 30
1.4 The Concept of Fragility 33
1.5 Relative Importance of Thermal Energy and Density 36
Appendix1 42
Appendix2 42
References 47
Chapter 2: Origin of Glass Formation 51
2.1 Thermodynamic Scaling of Molecular Dynamics in Viscous Systems 51
2.1.1 A General Idea of Thermodynamic Scaling 51
2.1.2 A New Measure of the Relative Temperature-Volume Influence on Molecular Dynamics 54
2.1.3 The Relaxation Time Description in Accordance with Thermodynamic Scaling 59
2.1.4 Thermodynamic Scaling on Isothermal Conditions and Its Consequences 64
2.1.5 Doubts About the Thermodynamic Scaling Universality 67
2.2 The Role of Monomer Volume and Local Packing on the Glass-Transition Dynamics 73
References 76
Chapter 3: Models of Temperature-Pressure Dependence of Structural Relaxation Time 78
3.1 The Generalized Vogel-Fulcher-Tammann Equation 78
3.2 The Adam-Gibbs Model 79
3.3 The Avramov Model 82
3.4 Cluster Kinetics Model 86
3.5 Defect Diffusion Model 90
3.6 Dynamic Lattice Liquid Model 95
References 98
Chapter 4: New Physics Gained by the Application of Pressure in the Study of Dynamics of Glass Formers 100
4.1 Dynamics Under Pressure 100
4.2 General Dynamic Properties of Glass Formers Discovered by Applying Pressure 101
4.2.1 Coinvariance of taua and Width of Dispersion to Changes in P and T 101
4.2.2 Crossover of T or P Dependence of ta (or h ) at the Sameta (or h ) Independent on T, P, and V at the Crossover 104
4.2.2.1 Experimental Facts 104
4.2.2.2 Coupling Model Explanation 106
4.2.3 An Important Class of Secondary Relaxations Bearing Strong Connection to the a-Relaxation 109
4.2.3.1 Spin-Lattice Relaxation Weighted Stimulated-Echo Spectroscopy 110
4.2.3.2 Invariance of the Ratio tauJG /taua for Different T and P When taua Is Kept Constant 110
4.2.3.3 TVgamma-Dependence of tauJG 114
Evidence Indicating T-1V-gamma: Dependence Originating from the Primitive Relaxation 114
4.2.3.4 Dependences of the Global and Segmental Dynamics in Polymers on TVgamma: Same gamma but Different Functional Forms 115
4.2.3.5 Change of T-Dependence of JG beta-Relaxation Time and Relaxation Strength on Crossing Tg 116
4.2.3.6 Relation Between the Activation Energies of tauJG and taua in the Glassy State 117
4.2.3.7 Pressure-Temperature History Dependence of tauJG in the Glassy State 117
4.2.3.8 JG beta-Relaxation Causes Cage Decay and Terminates the Nearly Constant Loss 122
4.2.3.9 JG beta-Relaxation Is Responsible for the Anomalous T-Dependence of gamma-Relaxation Time 123
4.3 Conclusions 126
References 127
Chapter 5: Pressure Effects on Polymer Blends 132
5.1 Theoretical Background 132
5.2 Effect of Pressure on the Dynamics of Miscible Polymer Blends: Dynamic Heterogeneity 134
5.2.1 Athermal Polymer Blends/Copolymers (PI-PVE, PMMA/PEO) 136
5.2.1.1 PI-b-PVE 136
5.2.1.2 PMMA/PEO 138
5.2.2 Miscible But Not Athermal Polymer Blends (PS/PMPS, PS/PVME, and PCHMA/PaMS) 142
5.2.2.1 PS/PMPS 143
5.2.2.2 PS/PVME 147
5.2.2.3 PCHMA/PaMS 150
5.2.3 Polymer Blends with Strong Specific Interactions 151
5.3 Effect of Pressure on Nanophase Separated Copolymers 152
5.3.1 PMVE-b-PiBVE 153
5.3.2 pODMA-b-ptBA-b-pODMA 155
References 157
Chapter 6: Polypeptide Dynamics 159
6.1 Introduction 159
6.2 Polypeptide Liquid-to-Glass ``Transition´´ and its Origin 160
6.3 Correlation Length of a-Helices 169
6.4 Effects of Nanoconfinement on the Peptide Secondary Structure and Dynamics 172
6.4.1 ``Soft´´ Confinement: Confinement Within the Nanodomains of Block Copolypeptides 172
6.4.2 ``Hard´´ Confinement: Confinement Inside Nanoporous Anodic Aluminum Oxide 173
6.5 Conclusion 176
References 177
Index 179