NMR Spectroscopy and Polymer Microstructure

The various techniques used to analyze the microstructures of polymers are presented in this book. High resolution and solid state techniques are described, and applications to both synthetic and biological polymers are discussed in detail. Particular emphasis is placed on the determination of polymer microstructure by NMR spectroscopy. Here attention is drawn to the connection between the microstructures and NMR spectra of polymers, and it is demonstrated that the local polymer conformation provides this link. The numerous examples illustrating this connection are a special feature of the book.

Alan Tonelli received a B.S. in Chemical Engineering from the University of Kansas in 1964 and a Ph.D. in Polymer Chemistry from Stanford in 1968, where he was associated with the late Professor Paul J. Flory. He was a member of the Polymer Chemistry Research Department at AT&T-Bell Laboratories, Murray Hill, NJ, for 23 years and in 1991 joined the Fiber & Polymer Science Program in the College of Textiles at North Carolina State University in Raleigh, NC, where he is currently the INVISTA Professor of Fiber and Polymer Chemistry. His research interests include the configurations, conformations, and structures of synthetic and biological polymers, their determination, principally by NMR and Kerr effect observations, and establishing their effects on the physical properties of polymer materials. Most recently, the formation of and coalescence from noncovalent crystalline inclusion compounds (ICs) formed between cyclodextrin (CD) hosts and polymer guests have been used to nanostructure bulk polymers, including homopolymers and their blends, and block copolymers. In addition, small-molecule guest-CD-ICs (crystalline) and -rotaxanes (soluble), and the covalent incorporation of CDs into polymers both during and subsequent to their syntheses, have been used to improve the delivery of additives to polymer materials.

Preface

1. The Microstructure of Polymer Chains

1.1 Introduction

1.2 Polymers Are Macromolecules

1.3 Polymer Microstructures from Polymerization of Monomers

1.3.1 Directional Isomerism

1.3.2 Stereochemical Isomerism

1.3.3 Geometrical Isomerism

1.3.4 Truly Asymmetric Polymers

1.3.5 Copolymer Sequences

1.4 Organization of Polymer Chains

1.5 Polymer Properties and Their Relation to Microstructure

2. Nuclear Magnetic Resonance

2.1 Introduction

2.2 The NMR Phenomenon

2.2.1 Resonance

2.2.2 Interactions and Relaxations of Nuclear Spins

2.2.3 Chemical Shift

2.2.4 Spin-Spin Coupling

2.3 Experimental Observation of NMR

3. High-Resolution NMR of Polymers

3.1 Introduction

3.2 1H NMR

3.3 13C NMR

3.4 High-Resolution 13C NMR in the Solid State

3.4.1 Dipolar Broadening

3.4.2 Chemical-Shift Anisotropy

3.4.3 Cross-Polarization

3.5 Two-Dimensional NMR

3.6 Other Nuclei--15N, 19F, 29Si, and 31p

4. 13C NMR of Polymers

4.1 Introduction

4.2 13C Chemical Shifts and Their Dependence on Microstructure

4.2.1 13C Nuclear Shielding

4.2.2 Substituent Effects on 13C Chemical Shifts

4.2.3 The γ-Substituent Effect in 13C NMR

4.2.4 γ-gauche Effects in 13C NMR

5. γ-gauche Effect Method of Predicting 13C NMR Chemical Shifts

5.1 Introduction

5.2 Polymer Conformations

5.2.1 Rotational Isomeric-State Model of Polymers

5.2.2 Average Bond Conformations

5.3 γ-gauche Effect Calculation of 13C NMR Chemical Shifts

5.3.1 Small-Molecule Example

5.3.2 Macromolecular Example

6. Determination of Stereosequences in Vinyl Polymers

6.1 Introduction

6.2 Traditional Methods

6.2.1 Stereoregular Polymers

6.2.2 Epimerization of Stereoregular Polymers

6.2.3 Model Compounds

6.2.4 Assumed Polymerization Mechanism

6.3 2D NMR Determination of Vinyl Polymer Stereosequence

6.4 Application of γ-gauche Effect Method

6.5 Establishing Vinyl Polymerization Mechanisms from Stereosequence Analysis

7. Microstructural Defects in Polymers

7.1 Introduction

7.2 Determining the Regiosequence of PVF2

7.2.1 13C NMR

7.2.2 19F NMR

7.2.3 2D 19F NMR

7.3 Regiosequence Defects in PPO

8. Copolymer Microstructure

8.1 Introduction

8.2 Comonomer Sequences

8.3 Copolymer Stereosequences

8.4 Copolymer Conformations

8.5 Copolymerization Mechanisms

9. Chemically Modified Polymers

9.1 Introduction

9.2 Transformation of PVC to Ethylene-Vinyl Chloride Copolymers

9.2.1 Tri-n-butyltin Hydride Reduction of PVC

9.2.2 Microstructures of E-V Copolymers

9.2.3 (n-Bu)3SnH Reduction of PVC Model Compounds

9.2.4 Computer Simulation of TCH and PVC Reduction

9.3 Modification of 1,4-Poly(butadienes) with Dihalocarbenes

9.3.1 Possible Microstructures in the Dihalocarbene Adducts of PBD

9.3.2 NMR of Dihalocarbene Adducts of PBD

10. Biopolymers

10.1 Introduction

10.2 Polypeptides

10.2.1 2D NMR Assignment of 1H Resonances

10.2.2 Determination of Polypeptide Conformation by 2D NMR

10.3 Polynucleotides

10.4 Polysaccharides

11. Solid Polymers

11.1 Introduction

11.2 Solid-State Polymer Conformation

11.3 Interchain Packing in Solid Polymers

11.4 Molecular Motion in Solid Polymers

11.5 Application of CPMAS/DD 13C NMR to Solid Polymers

11.5.1 Morphology and Motion in Polymer Crystals

11.5.2 Solid-Solid Polymer Phase Transitions

11.6 Other Nuclei Observed In Solid-State Polymer Spectra

11.6.1 CPMAS/DD 29Si NMR

11.6.2 MAS/DD 31p NMR

11.6.3 CPMAS/DD 15N NMR

11.7 Concluding Remarks

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NMR Spectroscopy and Polymer Microstructure The Conformational Connection

Summary

Author Biography

Table of Contents

Supplemental Materials