Wenbing Hu Polymer Physics A Molecular Approach ②Springer
Foreword There are many excellent books on polymer physics.It therefore requires some courage to write a new book on this subject.However,for the success of a book,the courage of the author is less important than the novelty of the approach that the book follows and,most importantly.it is crucial that this approach addresses an existing n erPhysics:A that Professor Wenbing Hu has writter aims to bring some of the key concepts of modern polymer physics to a readershi that is not familiar with this field.For this target audience,the present book will provide the first,and in some cases,the only introduction to a very wide and active field of research.In writing a book for this readership.Professor Hu had to make choices.Systematically,he has decided to focus on underlying physical concepts rather than on detailed mathematical descriptions.and he has tried to highlight the links between the subject matter of the book and the(many)application areas.In addition,as the title says,the book uses a"molecular xplain co and phenor ena this thesp en t to be very essful for the inese)editi of this b and it is therefore fortunate that the publishers have decided to publish an English translation. I should add that,on some topics,Professor Hu's book goes well beyond existing textbooks-this is,in particular,true of Professor Hu's own field of research: polymer crystallization,demixing.and the interplay of the two.To my knowledge, this is the first book that presents some of the new developments in this area of research at a level accessible to undergraduate students.Hence,the book may be of interest to a wider community than its original target readership. Cambridge Daan Frenkel March 2012
Foreword There are many excellent books on polymer physics. It therefore requires some courage to write a new book on this subject. However, for the success of a book, the courage of the author is less important than the novelty of the approach that the book follows and, most importantly, it is crucial that this approach addresses an existing need. Polymer Physics: A Molecular Approach that Professor Wenbing Hu has written aims to bring some of the key concepts of modern polymer physics to a readership that is not familiar with this field. For this target audience, the present book will provide the first, and in some cases, the only introduction to a very wide and active field of research. In writing a book for this readership, Professor Hu had to make choices. Systematically, he has decided to focus on underlying physical concepts rather than on detailed mathematical descriptions, and he has tried to highlight the links between the subject matter of the book and the (many) application areas. In addition, as the title says, the book uses a “molecular” picture to explain concepts and phenomena. This approach has proven to be very successful for the original (Chinese) edition of this book and it is therefore fortunate that the publishers have decided to publish an English translation. I should add that, on some topics, Professor Hu’s book goes well beyond existing textbooks—this is, in particular, true of Professor Hu’s own field of research: polymer crystallization, demixing, and the interplay of the two. To my knowledge, this is the first book that presents some of the new developments in this area of research at a level accessible to undergraduate students. Hence, the book may be of interest to a wider community than its original target readership. Cambridge Daan Frenkel March 2012 v
Preface to the English Edition Polymer physics covers all the physical aspects of macromolecular substances.If we introduced the subject according to the current classifications of structures and properties of polymers,the textbook would become thicker and thicker with the fast expansion of our knowledge,and would look like an encyclopedia.Such a textbook cannot meet the current demand for a more concise introduction within a time- limited schedule of university courses on polymer-related subjects.In fact,the published textbooks on polymer physics normally selected the content according to the author's p or to the speci ific traini ng su bjec s.On the other ha ragme r ph ysic need the course training on are available s su correlation among meaningful physical concepts of polymers as well as the useful theoretical tools for a fundamental analysis.On the basis of the above challenges,this book is intended to provide a concise entrance-level introduction on polymer physics.It tries to avoid the complicated mathematic treatments of modern theories,the trivial experimental techniques,the details of practical industrial processing.and the wide applications of polymers.Rather,the attention is only focused on three basic of p ens ciles of po phy dons,and tra der to elab orate istica dynamics and kinetic e mean-field ory and the scaling analysis)as wel I as their state-of the-art applications.The bool k may help readers to establish several key molecular-level pictures of polymer physics.The book targets senior undergraduate students,graduate students,teachers,and researchers,who are studying and working in the extensive fields of physical sciences.life sciences materials sciences,and engineering sciences relevant to physical aspects of polymers.Through a systematic study.the readers are expected to grasp the basic epts of polymer sics as well as the theoretical tools for a fundamental s of lish edition was basically version(Science Pul er in eijing.2011).with minor expansion on the histori aspects of some funda nental ideas and their original references.After the introduc tory chapter,the book has been split into three parts:chain structures,chain
Preface to the English Edition Polymer physics covers all the physical aspects of macromolecular substances. If we introduced the subject according to the current classifications of structures and properties of polymers, the textbook would become thicker and thicker with the fast expansion of our knowledge, and would look like an encyclopedia. Such a textbook cannot meet the current demand for a more concise introduction within a timelimited schedule of university courses on polymer-related subjects. In fact, the published textbooks on polymer physics normally selected the content according to the author’s personal taste or to the specific training subjects. On the other hand, nowadays on the Internet, fragmental concepts of polymer physics are available. However, the students still need the course training on the intrinsic correlations among meaningful physical concepts of polymers as well as the useful theoretical tools for a fundamental analysis. On the basis of the above challenges, this book is intended to provide a concise entrance-level introduction on polymer physics. It tries to avoid the complicated mathematic treatments of modern theories, the trivial experimental techniques, the details of practical industrial processing, and the wide applications of polymers. Rather, the attention is only focused on three basic aspects of comprehensive principles of polymer physics, including molecular structures, molecular motions, and phase transitions, in order to elaborate the basic statistical thermodynamics and kinetics (the mean-field theory and the scaling analysis) as well as their state-of-the-art applications. The book may help readers to establish several key molecular-level pictures of polymer physics. The book targets senior undergraduate students, graduate students, teachers, and researchers, who are studying and working in the extensive fields of physical sciences, life sciences, materials sciences, and engineering sciences relevant to physical aspects of polymers. Through a systematic study, the readers are expected to grasp the basic concepts of polymer physics as well as the theoretical tools for a fundamental analysis of macromolecules. The current English edition was basically translated from its recent Chinese version (Science Publisher in Beijing, 2011), with minor expansion on the historical aspects of some fundamental ideas and their original references. After the introductory chapter, the book has been split into three parts: chain structures, chain vii
多 Preface to the English Edition motions,and chain assembly.The first part introduces the relationships bet of ideal-chain conformation,the derivation of the equation of state for ideal rubbers,as well as the scaling analysis of some non-ideal-chain conformations (polymer solutions,polyelectrolyte,stretching,and spatial confinement).The sec ond part introduces the scaling analysis of chain dynamics,the relaxation behaviors of polymer deformation,and the viscoelastic behaviors of polymer flows.The third membly vihsewhich ineldes the tisi polymer s(Flory-Huggins mean-field latti and its de nts).pha and kinetic addition,mic separati of bloc copolyn (thermodynamics,kinetics.and mopholo) crystalliz with an extendec reading material on the interplay of phase separation and crystallization in polymer based multi-component systems.Each chapter is complemented at the end with several question sets to highlight some basic ideas. The delivery of this English edition was decided in a nice conversation with Dr.Stephen Soehnlen,the Springer editor.Prof.Daan Frenkel offered a perfect foreword.Prof.Yifu Ding and Dr.Ran Ni made a thorough proofreading o ver the and Prof. An Ch g Shi and Dr.Ja mie Hobhs made separa proofrea ding on the first and sec pters. With their great help.the presen book became more readable as a textbook The content of this book is limited by the author's academic background as well as by the pedagogic style of a textbook.It could not completely cover all the important academic ideas in the related fields or all the original references in the historical aspects.The author is mainly reponsible for any mistakes in the text.Friendly suggestions and comments are always most welcome! Wenbing Hu Juy,2012
motions, and chain assembly. The first part introduces the relationships between chemical structures of polymers and their physical behaviors, the Gaussian statistics of ideal-chain conformation, the derivation of the equation of state for ideal rubbers, as well as the scaling analysis of some non-ideal-chain conformations (polymer solutions, polyelectrolyte, stretching, and spatial confinement). The second part introduces the scaling analysis of chain dynamics, the relaxation behaviors of polymer deformation, and the viscoelastic behaviors of polymer flows. The third part introduces polymer assembly via phase transitions, which includes the statistical thermodynamics of polymer solutions (Flory-Huggins mean-field lattice theory and its developments), phase separation (its thermodynamics and kinetics; in addition, microphase separation of block copolymers), and polymer crystallization (thermodynamics, kinetics, and morphologies). The book ends with an extended reading material on the interplay of phase separation and crystallization in polymerbased multi-component systems. Each chapter is complemented at the end with several question sets to highlight some basic ideas. The delivery of this English edition was decided in a nice conversation with Dr. Stephen Soehnlen, the Springer editor. Prof. Daan Frenkel offered a perfect foreword. Prof. Yifu Ding and Dr. Ran Ni made a thorough proofreading over the original text, and Prof. An-Chang Shi and Dr. Jamie Hobbs made separate proofreading on the first and second chapters. With their great help, the present book became more readable as a textbook! The content of this book is limited by the author’s academic background as well as by the pedagogic style of a textbook. It could not completely cover all the important academic ideas in the related fields or all the original references in the historical aspects. The author is mainly reponsible for any mistakes in the text. Friendly suggestions and comments are always most welcome! Nanjing Wenbing Hu July, 2012 viii Preface to the English Edition
Contents 1 Introduction 1 1.1 What Are Polymers?. 1.2 Polymers in the Eyes of Physicists. 3 1.3 Role of Polymer Physics. 5 1.4 Focusing of this Book. 7 References. 9 Part I Chain Structure 2 Structure-Property Relationships #”中卡”0。卡”中”中卡卡中中。”卡卡” 13 2.1 Characterization of Chemical Structures. 13 2.2 Semi-Flexibility of Polymer Chains. 2.2.1 Freely Jointed Chains. 。,。，。1。 2.2.2 Freely Rotating Chains 16 2.2.3 Hindered Rotating Chains. 11 2.2.4 Characterization of Static Semi-Flexibility 2.3 Local Inter-Chain Interactions 2.4 Molecular Wei d The ir Distributions.· 3 2.4.1 Weight Effects. 2.4.2 Characterization of Molecular Weights. 34 2.5 Topological Architectures. 27 2.6 Sequence Irregularities. 2.6.1 Chemical Irregularities. 名 2.6.2 Geometrical Irregularities 2.6.3 Spatial Irregularities. References 32 ix
Contents 1 Introduction . 1 1.1 What Are Polymers? . 1 1.2 Polymers in the Eyes of Physicists . 3 1.3 Role of Polymer Physics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.4 Focusing of this Book . . . . 7 References . 9 Part I Chain Structure 2 Structure–Property Relationships . . . . . . . . . . . . . . . . . . . . . . . . . . 13 2.1 Characterization of Chemical Structures . . . . . . . . . . . . . . . . . . 13 2.2 Semi-Flexibility of Polymer Chains . . . . . . . . . . . . . . . . . . . . . . 14 2.2.1 Freely Jointed Chains . . . . . . . . . . . . . . . . . . . . . . . . . . 15 2.2.2 Freely Rotating Chains . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2.3 Hindered Rotating Chains . . . . . . . . . . . . . . . . . . . . . . . 17 2.2.4 Characterization of Static Semi-Flexibility of Polymers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 2.3 Local Inter-Chain Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.4 Molecular Weights and Their Distributions . . . . . . . . . . . . . . . . 23 2.4.1 Molecular Weight Effects . . . . . . . . . . . . . . . . . . . . . . . 23 2.4.2 Characterization of Molecular Weights . . . . . . . . . . . . . . 24 2.5 Topological Architectures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 2.6 Sequence Irregularities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 2.6.1 Chemical Irregularities . . . . . . . . . . . . . . . . . . . . . . . . . . 30 2.6.2 Geometrical Irregularities . . . . . . . . . . . . . . . . . . . . . . . . 30 2.6.3 Spatial Irregularities . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 ix
Contents 3 Conformation Statistics and Entropic Elasticity 3.1 Gaussian Distribution of End-to-End Distances of Polymer Coils. Statistical Mechanics of Rubber Elasticity. 35 3.2.1 Mechanics of Elasticity. 35 3.22 Thermodynamics of Elasticity. 35 323 Entropic Elasticity of a Deformed Polymer Coil. 3.2.4 Statistical Thermodynamics of a Cross-Linked Polymer Network 37 References. 41 4 Scaling Analysis of Real-Chain Conformations. 43 What Is the Scaling Analysis. 43 4.2 Single-Chain Conformation in Polymer Solutions. 4.2.1 An Introduction of Polymer Solutions. 44 4.2.2 Single-Chain Conformation in Athermal Dilute Solutions. 42.3 Single-Chain Conformation in athermal ted Soluti 51 4.2.4 4.3 Single 59 4.4 Single-Chain Conformation Under External Forces. 4.4.1 Stretching. 4.4.2 Compression. 4.4.3 Adsorption. References 72 PartⅡChain Motion 5 Sealing Analysis of Polymer Dynamics. 77 Simple Fluids. 77 5.2 5.3 Long Chains References. 90 6 Polvmer Deformation 93 61 Characteristics of Polymer Deformation mer Defo 97 62) xatio cular Motions 9 oltzmann Superpos ion Principl 6.2.3 Time-Temperature Superposition Principle . 6.2.4 Dynamic Mechanical Analysis. 105 6.3 Glass Transition and Fluid Transition. 109 6.3.1 Glass Transition Phenomena. 109 6.3.2 Glass Transition Theories. 111
3 Conformation Statistics and Entropic Elasticity . . . . . . . . . . . . . . . 33 3.1 Gaussian Distribution of End-to-End Distances of Polymer Coils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 3.2 Statistical Mechanics of Rubber Elasticity . . . . . . . . . . . . . . . . . 35 3.2.1 Mechanics of Elasticity . . . . . . . . . . . . . . . . . . . . . . . . . 35 3.2.2 Thermodynamics of Elasticity . . . . . . . . . . . . . . . . . . . . 35 3.2.3 Entropic Elasticity of a Deformed Polymer Coil . . . . . . . 37 3.2.4 Statistical Thermodynamics of a Cross-Linked Polymer Network . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41 4 Scaling Analysis of Real-Chain Conformations . . . . . . . . . . . . . . . . 43 4.1 What Is the Scaling Analysis? . . . . . . . . . . . . . . . . . . . . . . . . . . 43 4.2 Single-Chain Conformation in Polymer Solutions . . . . . . . . . . . . 44 4.2.1 An Introduction of Polymer Solutions . . . . . . . . . . . . . . . 44 4.2.2 Single-Chain Conformation in Athermal Dilute Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 4.2.3 Single-Chain Conformation in Athermal Concentrated Solutions . . . . . . . . . . . . . . . . . . . . . . . . . 51 4.2.4 Single-Chain Conformation in Thermal Dilute Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 4.3 Single-Chain Conformation in Polyelectrolyte Solutions . . . . . . . 59 4.4 Single-Chain Conformation Under External Forces . . . . . . . . . . 66 4.4.1 Stretching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 4.4.2 Compression . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 4.4.3 Adsorption . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Part II Chain Motion 5 Scaling Analysis of Polymer Dynamics . . . . . . . . . . . . . . . . . . . . . . 77 5.1 Simple Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 5.2 Short Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 5.3 Long Chains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 6 Polymer Deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93 6.1 Characteristics of Polymer Deformation . . . . . . . . . . . . . . . . . . . 93 6.2 Relaxation of Polymer Deformation . . . . . . . . . . . . . . . . . . . . . 97 6.2.1 Relaxation Via Molecular Motions . . . . . . . . . . . . . . . . . 97 6.2.2 Boltzmann Superposition Principle . . . . . . . . . . . . . . . . . 100 6.2.3 Time–Temperature Superposition Principle . . . . . . . . . . . 103 6.2.4 Dynamic Mechanical Analysis . . . . . . . . . . . . . . . . . . . . 105 6.3 Glass Transition and Fluid Transition . . . . . . . . . . . . . . . . . . . . 109 6.3.1 Glass Transition Phenomena . . . . . . . . . . . . . . . . . . . . . 109 6.3.2 Glass Transition Theories . . . . . . . . . . . . . . . . . . . . . . . . 111 x Contents
Contents xi 6.3.3 Chemical-Structure Dependence of Glass Transition. 116 118 6.4 Conventiona References hanical Analysis.·. 123 7 Polymer Flow.· 7.1 Introduction to Rheology. 127 7.1.1 What Is Rheology?. 127 7.12 Classification of the Flow 127 7 1 3 Iaminar Flow 128 7.14 Non-Newtonian Fluids 130 72 Char acteristics of Poly mer Flow. 132 7.3 Viscoelastic Phenomena of Polymer Flow. 140 References. 143 Part III Chain Assembly 8 Statistical Thermodynamics of Polymer Solutions. 147 8.1 Polymer-Based Multi-Component Systems 147 8.2 Flory-Huggins Lattice Theory of Polymer Solutions 149 g21 Advantages of the Lattice Model 149 8.2.2 Basic As umptions of Flory-Huggins Lattice h 823 159 0n0 xing En 8.2.4 Calculation of Mixing Heat and Free Energy. 155 8.3 Developments of Flory-Huggins Theory. 8.3.1 Simple Additions. 156 8.3.2 Compressible Fluids. 159 8 33 Dilute Solutions 160 8.3.4 Concentration Dependence of Interaction D meter: 162 8.3.5 I er The 8.3.6 Semi-Flexible Polymers. References. 165 9 Polymer Phase Separation. 167 9.1 Thermodynamics of Phase Separation. 16 9.2 Kinetics of Phase Separation. 171 9.3 Microphase Separation of Diblock Copolymers. 179 References. 187 Thermodynamics of Polymer Crystalliza 10.2 Statistical Thermodynamics of Polymer Crystallization
6.3.3 Chemical-Structure Dependence of Glass Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116 6.3.4 Fluid Transition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 6.4 Conventional Mechanical Analysis . . . . . . . . . . . . . . . . . . . . . . 119 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 7 Polymer Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 7.1 Introduction to Rheology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 7.1.1 What Is Rheology? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 7.1.2 Classification of the Flow . . . . . . . . . . . . . . . . . . . . . . . . 127 7.1.3 Laminar Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 7.1.4 Non-Newtonian Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . 130 7.2 Characteristics of Polymer Flow . . . . . . . . . . . . . . . . . . . . . . . . 132 7.3 Viscoelastic Phenomena of Polymer Flow . . . . . . . . . . . . . . . . . 140 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143 Part III Chain Assembly 8 Statistical Thermodynamics of Polymer Solutions . . . . . . . . . . . . . 147 8.1 Polymer-Based Multi-Component Systems . . . . . . . . . . . . . . . . 147 8.2 Flory-Huggins Lattice Theory of Polymer Solutions . . . . . . . . . . 149 8.2.1 Advantages of the Lattice Model . . . . . . . . . . . . . . . . . . 149 8.2.2 Basic Assumptions of Flory-Huggins Lattice Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150 8.2.3 Calculation of Mixing Entropy . . . . . . . . . . . . . . . . . . . . 152 8.2.4 Calculation of Mixing Heat and Free Energy . . . . . . . . . . 155 8.3 Developments of Flory-Huggins Theory . . . . . . . . . . . . . . . . . . 156 8.3.1 Simple Additions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 8.3.2 Compressible Fluids . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 8.3.3 Dilute Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160 8.3.4 Concentration Dependence of Interaction Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 8.3.5 Lattice-Cluster Theory Considering Molecular Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . 162 8.3.6 Semi-Flexible Polymers . . . . . . . . . . . . . . . . . . . . . . . . . 163 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 165 9 Polymer Phase Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 167 9.1 Thermodynamics of Phase Separation . . . . . . . . . . . . . . . . . . . . 167 9.2 Kinetics of Phase Separation . . . . . . . . . . . . . . . . . . . . . . . . . . . 171 9.3 Microphase Separation of Diblock Copolymers . . . . . . . . . . . . . 179 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 184 10 Polymer Crystallization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 10.1 Thermodynamics of Polymer Crystallization . . . . . . . . . . . . . . 187 10.2 Statistical Thermodynamics of Polymer Crystallization . . . . . . . 192 Contents xi
xii Contents 10.3 Crystalline Structures of Polymers. 197 10.3.1 Hierarchical Crystalline Structures. 19 10.3.2 Unit Cells of Polymer Crystals. 198 10.3.3 Folded-Chain Lamellar Crvstals. 200 10.3.4 Morphology of Polymer Crystals. 203 10.4 Kinetics of Polymer Crystallization. 208 10.4.1 Nucleation of Polymer Crystallization. 208 10.4.2 Microscopic Mechanism of Polymer Crystal Gr wth 212 10.4.3 Overall Kinetic Analysis of Polymer Crystallization. References. 11 Interplay Between Phase Separation and Polymer Crystallization. 223 11.1 Complexity of Polymer Phase Transitions. 223 11.2 Enhanced Phase Separation in the Blends Containing Crystallizable Polymers. 226 11.3 Accelerated Crystal Nucleation in the Concentrated Ph 11.4 Accel rate on at Liquid Interfaces. Accelerated Crystal Nucleation in the Single-Chain Systems. 232 11.6 Interplay of Phase Transitions in Diblock Copolymers. 235 11.7 Implication of Interplays in Biological Systems. References. 238 ndex. 241
10.3 Crystalline Structures of Polymers . . . . . . . . . . . . . . . . . . . . . . 197 10.3.1 Hierarchical Crystalline Structures . . . . . . . . . . . . . . . 197 10.3.2 Unit Cells of Polymer Crystals . . . . . . . . . . . . . . . . . . 198 10.3.3 Folded-Chain Lamellar Crystals . . . . . . . . . . . . . . . . . 200 10.3.4 Morphology of Polymer Crystals . . . . . . . . . . . . . . . . 203 10.4 Kinetics of Polymer Crystallization . . . . . . . . . . . . . . . . . . . . . 208 10.4.1 Nucleation of Polymer Crystallization . . . . . . . . . . . . . 208 10.4.2 Microscopic Mechanism of Polymer Crystal Growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 212 10.4.3 Overall Kinetic Analysis of Polymer Crystallization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 214 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 219 11 Interplay Between Phase Separation and Polymer Crystallization . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 223 11.1 Complexity of Polymer Phase Transitions . . . . . . . . . . . . . . . . 223 11.2 Enhanced Phase Separation in the Blends Containing Crystallizable Polymers . . . . . . . . . . . . . . . . . . . . . 226 11.3 Accelerated Crystal Nucleation in the Concentrated Phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 11.4 Accelerated Crystal Nucleation at Liquid Interfaces . . . . . . . . . 230 11.5 Accelerated Crystal Nucleation in the Single-Chain Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232 11.6 Interplay of Phase Transitions in Diblock Copolymers . . . . . . . 235 11.7 Implication of Interplays in Biological Systems . . . . . . . . . . . . 236 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 xii Contents
Chapter 1 Introduction 1.1 What Are Polymers? Polymers are our molecular views on certain chemical substances.The views have been established in our long-lasting exploration and exploitation of materials in nature.The term "polymers"is commonly used to describe a broad range of materials,from synthetic materials,such as plastics,rubbers,fibers,coatings, filtration membranes,adsorption resins and adhesives;to natural materials,such as cellulose,starches,natural rubbers,silks,hairs,and chitins;and even to the prototypes of bio-macromolecules.such as DNA.RNA and proteins,which are the basic substances for highly diverse creatures. There is a long history for us evolu the Gree k philosopher Leucippus and uggested that,an indivisible minimum substance called atoms constituted our world.Almost at the same time,Empedocles proposed that the world was formed by four elements,i.e. water,air,fire,and earth.Later on,Plato set up the Academy at Athens,inherited the atomic theory,and also advocated the four-element theory on the basis of the formal logic system of geometries. In the next 2.000 years,the alchemists discovered more and more elements.Till to eighteenth century.Lavoisier named the elem ents of oxyg en and hydroo en and chemical rea t al.1783).This rth of ch emistry.At the begI ning of nineteenth century Dalton proposed that each molecule contains a fixed ratio of atoms among several elements(Dalton 1808).This theory was another milestone that opened the gate to modern chemistry.Since then,the atomic and molecular theory became the main stream of chemistry. In the field of physics,in 1880s,Boltzmann invented statistical thermodynamics according to the Maxwell's theory of the motions of atoms(Boltzmann 1872).In 1905.Einstein elucidated that the stochastic Brownian motions of atoms are mainly W.H.Po小mer Physics,D0I10.1007/978-3-7091-0670-9_1, C Springer-Verlag Wien 2013
Chapter 1 Introduction 1.1 What Are Polymers? Polymers are our molecular views on certain chemical substances. The views have been established in our long-lasting exploration and exploitation of materials in nature. The term “polymers” is commonly used to describe a broad range of materials, from synthetic materials, such as plastics, rubbers, fibers, coatings, filtration membranes, adsorption resins and adhesives; to natural materials, such as cellulose, starches, natural rubbers, silks, hairs, and chitins; and even to the prototypes of bio-macromolecules, such as DNA, RNA and proteins, which are the basic substances for highly diverse creatures. There is a long history for us to recognize polymers. Let us start with the early evolution of our molecular views (Rupp 2005). As early as in the middle of 500 BC, the Greek philosopher Leucippus and his follower Democritus suggested that, an indivisible minimum substance called atoms constituted our world. Almost at the same time, Empedocles proposed that the world was formed by four elements, i.e., water, air, fire, and earth. Later on, Plato set up the Academy at Athens, inherited the atomic theory, and also advocated the four-element theory on the basis of the formal logic system of geometries. In the next 2,000 years, the alchemists discovered more and more elements. Till to eighteenth century, Lavoisier named the elements of oxygen and hydrogen, and proved the mass conservation in chemical reactions (Lavoisier et al. 1783). This milestone delivered the birth of chemistry. At the beginning of nineteenth century, Dalton proposed that each molecule contains a fixed ratio of atoms among several elements (Dalton 1808). This theory was another milestone that opened the gate to modern chemistry. Since then, the atomic and molecular theory became the main stream of chemistry. In the field of physics, in 1880s, Boltzmann invented statistical thermodynamics according to the Maxwell’s theory of the motions of atoms (Boltzmann 1872). In 1905, Einstein elucidated that the stochastic Brownian motions of atoms are mainly W. Hu, Polymer Physics, DOI 10.1007/978-3-7091-0670-9_1, # Springer-Verlag Wien 2013 1
I Introduction for their().The epoch-markin ideas above,along with the flourishing of quantum mechanics created a solid foundation for atomic and molecular views of chemical substances.The atomic view has been reinforced by modern techniques,for example,scanning tunneling microscopy,which is capable of visualizing and even manipulating individual atoms (Binnig and Rohrer 1986).Nowadays,we define the molecules,including ions and mono-atomic molecules,as the smallest units that maintain the chemical properties of pure substances,and define the atoms as the smallest units that rep nt the prop s of eleme nts in molecules and in chemical reactior Molecule al na the che cal operties, imply tha their mola too l ase Th hen Stau cromolecules"in 1920(St from the whole academic community.However,he unflinchingly fought for his argument,and collected various concrete evidences to prove that the chemical compounds in his hand contained more than 1.000 atoms,and their molar masses reached more than 10 kilograms per mole.He eventually persuaded his colleagues in the community and won the Nobel Prize in Chemistry in 1953 for his work on romolecules.Nowadays.it has been well known that the molar msof ould he ral P rem rep wouldno affec their or physical properties concep of Macromolecules"has indeed challenged our common sense that molecules are the smallest structural units maintaining the properties of pure substances. In 1996,the International Union of Pure and Applied Chemistry (IPUAC) published the recommendation of polymer terms (Jenkins et al.1996).It provided the definition below: Macromol ecule:polymer molecule A m which ess of low relative molecular mass Notes: (1)In many cases,especia ally for synthetic polymers,a molecule can be regarded as having macromolecu for which the properties may a high relativ mass a and e ntiall tition of units ed actu mocuof lowreive molecular mass it may be describedeithr lar or polymeric.or by polymer used adjectivally. The definition above is flexible enough to accommodate the diverse macromo lecular compounds encountered by chemists.But such a definition is not satisfac tory to physicists,because it does not reflect the basic molecular structure that determines most of the unique physical behaviors of polymers
responsible for their self-diffusion in the liquid (Einstein 1905). The epoch-marking ideas above, along with the flourishing of quantum mechanics, created a solid foundation for atomic and molecular views of chemical substances. The atomic view has been reinforced by modern techniques, for example, scanning tunneling microscopy, which is capable of visualizing and even manipulating individual atoms (Binnig and Rohrer 1986). Nowadays, we define the molecules, including ions and mono-atomic molecules, as the smallest units that maintain the chemical properties of pure substances, and define the atoms as the smallest units that represent the properties of elements in molecules and in chemical reactions. Molecules, as the minimal units maintaining the chemical properties, imply that their molar mass could not be too large. Therefore, when Staudinger proposed the concept of “Macromolecules” in 1920 (Staudinger 1920), he met a strong objection from the whole academic community. However, he unflinchingly fought for his argument, and collected various concrete evidences to prove that the chemical compounds in his hand contained more than 1,000 atoms, and their molar masses reached more than 10 kilograms per mole. He eventually persuaded his colleagues in the community and won the Nobel Prize in Chemistry in 1953 for his work on macromolecules. Nowadays, it has been well known that the molar mass of polymers could be so large that, removing several repeating units would not significantly affect their chemical or physical properties. The concept of “Macromolecules” has indeed challenged our common sense that molecules are the smallest structural units maintaining the properties of pure substances. In 1996, the International Union of Pure and Applied Chemistry (IPUAC) published the recommendation of polymer terms (Jenkins et al. 1996). It provided the definition below: Macromolecule; polymer molecule A molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass. Notes: (1) In many cases, especially for synthetic polymers, a molecule can be regarded as having a high relative molecular mass if the addition or removal of one or a few of the units has a negligible effect on the molecular properties. This statement fails in the case of certain macromolecules for which the properties may be critically dependent on fine details of the molecular structure. (2) If a part or the whole of the molecule has a high relative molecular mass and essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass, it may be described as either macromolecular or polymeric, or by polymer used adjectivally. The definition above is flexible enough to accommodate the diverse macromolecular compounds encountered by chemists. But such a definition is not satisfactory to physicists, because it does not reflect the basic molecular structure that determines most of the unique physical behaviors of polymers. 2 1 Introduction