Polymer Chemistry

Introduction to Chain Molecules     1Introduction     1How Big Is Big?     3Molecular Weight     3Spatial Extent     5Linear and Branched Polymers, Homopolymers, and Copolymers     7Branched Structures     7Copolymers     9Addition, Condensation, and Natural Polymers     11Addition and Condensation Polymers     11Natural Polymers     13Polymer Nomenclature     18Structural Isomerism     20Positional Isomerism     20Stereo Isomerism     21Geometrical Isomerism     22Molecular Weights and Molecular Weight Averages     24Number-, Weight-, and z-Average Molecular Weights     25Polydispersity Index and Standard Deviation     26Examples of Distributions     28Measurement of Molecular Weight     31General Considerations     31End Group Analysis     32MALDI Mass Spectrometry     35Preview of Things to Come     37Chapter Summary     38Problems     38References     41Further Readings     41Step-Growth Polymerization     43Introduction     43Condensation Polymers: One Step at a Time     43Classes of Step-Growth Polymers     43First Look at the Distribution of Products     44A First Look at Reactivity and Reaction Rates     46Kinetics of Step-Growth Polymerization     49Catalyzed Step-Growth Reactions     50How Should Experimental Data Be Compared with Theoretical Rate Laws?     52Uncatalyzed Step-Growth Reactions     53Distribution of Molecular Sizes     55Mole Fractions of Species     56Weight Fractions of Species     58Polyesters     60Polyamides     64Stoichiometric Imbalance     67Chapter Summary     71Problems     71References     76Further Readings     76Chain-Growth Polymerization     77Introduction     77Chain-Growth and Step-Growth Polymerizations: Some Comparisons     77Initiation     79Initiation Reactions     80Fate of Free Radicals     81Kinetics of Initiation     82Photochemical Initiation     84Temperature Dependence of Initiation Rates     85Termination     86Combination and Disproportionation     86Effect of Termination on Conversion to Polymer     88Stationary-State Radical Concentration     89Propagation     90Rate Laws for Propagation     91Temperature Dependence of Propagation Rates     92Kinetic Chain Length     94Radical Lifetime     96Distribution of Molecular Weights     99Distribution of i-mers: Termination by Disproportionation     99Distribution of i-mers: Termination by Combination     102Chain Transfer     104Chain Transfer Reactions     105Evaluation of Chain Transfer Constants     106Chain Transfer to Polymer     108Suppressing Polymerization     109Chapter Summary     110Problems     110References     114Further Readings     115Controlled Polymerization     117Introduction     117Poisson Distribution for an Ideal Living Polymerization     118Kinetic Scheme     119Breadth of the Poisson Distribution     122Anionic Polymerization     126Block Copolymers, End-Functional Polymers, and Branched Polymers by Anionic Polymerization     129Block Copolymers     129End-Functional Polymers     133Regular Branched Architectures     135Cationic Polymerization     137Aspects of Cationic Polymerization     138Living Cationic Polymerization     140Controlled Radical Polymerization     142General Principles of Controlled Radical Polymerization     142Particular Realizations of Controlled Radical Polymerization     144Atom Transfer Radical Polymerization (ATRP)     144Stable Free-Radical Polymerization (SFRP)     145Reversible Addition-Fragmentation Transfer (RAFT) Polymerization     146Polymerization Equilibrium     147Ring-Opening Polymerization (ROP)     150General Aspects     150Specific Examples of Living Ring-Opening Polymerizations     152Poly(ethylene oxide)     152Polylactide     153Poly(dimethylsiloxane)     154Ring-Opening Metathesis Polymerization (ROMP)     155Dendrimers     156Chapter Summary      160Problems     161References     163Further Readings     163Copolymers, Microstructure, and Stereoregularity     165Introduction     165Copolymer Composition     166Rate Laws     166Composition versus Feedstock     168Reactivity Ratios     170Effects of r Values     171Relation of Reactivity Ratios to Chemical Structure     173Resonance and Reactivity     175A Closer Look at Microstructure     179Sequence Distributions     180Terminal and Penultimate Models     183Copolymer Composition and Microstructure: Experimental Aspects     185Evaluating Reactivity Ratios from Composition Data     185Spectroscopic Techniques     188Sequence Distribution: Experimental Determination     190Characterizing Stereoregularity     193A Statistical Description of Stereoregularity     196Assessing Stereoregularity by Nuclear Magnetic Resonance     200Ziegler-Natta Catalysts     205Single-Site Catalysts     208Chapter Summary     211Problems      212References     216Further Readings     216Polymer Conformations     217Conformations, Bond Rotation, and Polymer Size     217Average End-to-End Distance for Model Chains     219The Freely Jointed Chain     220The Freely Rotating Chain     221Hindered Rotation Chain     222Characteristic Ratio and Statistical Segment Length     223Semiflexible Chains and the Persistence Length     225Persistence Length of Flexible Chains     227Worm-Like Chains     228Radius of Gyration     230Spheres, Rods, and Coils     234Distributions for End-to-End Distance and Segment Density     235Distribution of the End-to-End Vector     236Distribution of the End-to-End Distance     239Distribution about the Center of Mass     240Self-Avoiding Chains: A First Look     241Chapter Summary     242Problems     242References     244Further Readings     245Thermodynamics of Polymer Solutions     247Review of Thermodynamic and Statistical Thermodynamic Concepts     247Regular Solution Theory      249Regular Solution Theory: Entropy of Mixing     249Regular Solution Theory: Enthalpy of Mixing     251Flory-Huggins Theory     254Flory-Huggins Theory: Entropy of Mixing by a Quick Route     255Flory-Huggins Theory: Entropy of Mixing by a Longer Route     255Flory-Huggins Theory: Enthalpy of Mixing     257Flory-Huggins Theory: Summary of Assumptions     258Osmotic Pressure     258Osmotic Pressure: General Case     259Number-Average Molecular Weight     261Osmotic Pressure: Flory-Huggins Theory     263Phase Behavior of Polymer Solutions     264Overview of the Phase Diagram     265Finding the Binodal     268Finding the Spinodal     269Finding the Critical Point     270Phase Diagram from Flory-Huggins Theory     271What's in [chi]?     275[chi] from Regular Solution Theory     275[chi] from Experiment     276Further Approaches to [chi]     278Excluded Volume and Chains in a Good Solvent     280Chapter Summary     283Problems     284References     287Further Readings      288Light Scattering by Polymer Solutions     289Introduction: Light Waves     289Basic Concepts of Scattering     291Scattering from Randomly Placed Objects     292Scattering from a Perfect Crystal     292Origins of Incoherent and Coherent Scattering     293Bragg's Law and the Scattering Vector     294Scattering by an Isolated Small Molecule     296Scattering from a Dilute Polymer Solution     298The Form Factor and the Zimm Equation     304Mathematical Expression for the Form Factor     305Form Factor for Isotropic Solutions     306Form Factor as qR[subscript g][Right Arrow]0     307Zimm Equation     307Zimm Plot     308Scattering Regimes and Particular Form Factors     312Experimental Aspects of Light Scattering     314Instrumentation     316Calibration     317Samples and Solutions     319Refractive Index Increment     319Chapter Summary     320Problems     321References     325Further Readings     325Dynamics of Dilute Polymer Solutions      327Introduction: Friction and Viscosity     327Stokes' Law and Einstein's Law     330Viscous Forces on Rigid Spheres     331Suspension of Spheres     332Intrinsic Viscosity     334General Considerations     334Mark-Houwink Equation     336Measurement of Viscosity     341Poiseuille Equation and Capillary Viscometers     341Concentric Cylinder Viscometers     345Diffusion Coefficient and Friction Factor     346Tracer Diffusion and Hydrodynamic Radius     347Mutual Diffusion and Fick's Laws     348Dynamic Light Scattering     354Hydrodynamic Interactions and Draining     357Size Exclusion Chromatography (SEC)     360Basic Separation Process     361Separation Mechanism     365Two Calibration Strategies     367Limitations of Calibration by Standards     367Universal Calibration     368Size Exclusion Chromatography Detectors     369RI Detector     369UV-Vis Detector     370Light Scattering Detector     371Viscometer     372Chapter Summary      372Problems     373References     378Further Readings     379Networks, Gels, and Rubber Elasticity     381Formation of Networks by Random Cross-Linking     381Definitions     381Gel Point     383Polymerization with Multifunctional Monomers     386Calculation of the Branching Coefficient     387Gel Point     388Molecular-Weight Averages     389Elastic Deformation     392Thermodynamics of Elasticity     394Equation of State     394Ideal Elastomers     396Some Experiments on Real Rubbers     397Statistical Mechanical Theory of Rubber Elasticity: Ideal Case     398Force to Extend a Gaussian Chain     400Network of Gaussian Strands     402Modulus of the Gaussian Network     403Further Developments in Rubber Elasticity     406Non-Gaussian Force Law     406Front Factor     407Network Defects     408Mooney-Rivlin Equation     409Swelling of Gels     410Modulus of a Swollen Rubber     411Swelling Equilibrium      412Chapter Summary     414Problems     416References     418Further Readings     418Linear Viscoelasticity     419Basic Concepts     419Stress and Strain     421Viscosity, Modulus, and Compliance     421Viscous and Elastic Responses     422Response of the Maxwell and Voigt Elements     423Transient Response: Stress Relaxation     423Transient Response: Creep     425Dynamic Response: Loss and Storage Moduli     426Dynamic Response: Complex Modulus and Complex Viscosity     429Boltzmann Superposition Principle     430Bead-Spring Model     432Ingredients of the Bead-Spring Model     432Predictions of the Bead-Spring Model     434Zimm Model for Dilute Solutions, Rouse Model for Unentangled Melts     439Phenomenology of Entanglement     444Rubbery Plateau     444Dependence of M[subscript e] on Molecular Structure     447Reptation Model     450Reptation Model: Longest Relaxation Time and Diffusivity     451Reptation Model: Viscoelastic Properties     453Reptation Model: Additional Relaxation Processes     456Aspects of Experimental Rheometry     458Shear Sandwich and Cone and Plate Rheometers     458Further Comments about Rheometry     459Chapter Summary     460Problems     461References     464Further Readings     464Glass Transition     455Introduction     455Definition of a Glass     455Glass and Melting Transitions     466Thermodynamic Aspects of the Glass Transition     468First-Order and Second-Order Phase Transitions     469Kauzmann Temperature     471Theory of Gibbs and DiMarzio     472Locating the Glass Transition Temperature     474Dilatometry     474Calorimetry     476Dynamic Mechanical Analysis     478Free Volume Description of the Glass Transition     479Temperature Dependence of the Free Volume     480Free Volume Changes Inferred from the Viscosity     481Williams-Landel-Ferry Equation     483Time-Temperature Superposition     486Factors that Affect the Glass Transition Temperature     491Dependence on Chemical Structure     491Dependence on Molecular Weight     492Dependence on Composition     492Mechanical Properties of Glassy Polymers     496Basic Concepts     496Crazing, Yielding, and the Brittle-to-Ductile Transition     498Role of Chain Stiffness and Entanglements     501Chapter Summary     504Problems     505References     508Further Readings     508Crystalline Polymers     511Introduction and Overview     511Structure and Characterization of Unit Cells     513Classes of Crystals     513X-Ray Diffraction     515Examples of Unit Cells     518Thermodynamics of Crystallization: Relation of Melting Temperature to Molecular Structure     521Structure and Melting of Lamellae     526Surface Contributions to Phase Transitions     526Dependence of T[subscript m] on Lamellar Thickness     527Dependence of T[subscript m] on Molecular Weight     530Experimental Characterization of Lamellar Structure     532Kinetics of Nucleation and Growth     536Primary Nucleation     537Crystal Growth     539Morphology of Semicrystalline Polymers     545Spherulites     545Nonspherulitic Morphologies     548Kinetics of Bulk Crystallization     551Avrami Equation     552Kinetics of Crystallization: Experimental Aspects     556Chapter Summary     561Problems     562References     565Further Readings     565Appendix     567Series Expansions     567Summation Formulae     568Transformation to Spherical Coordinates     569Some Integrals of Gaussian Functions     570Complex Numbers     572Index     575