Chapter 7: Study Guide and Self-Assessment
In the first few chapters of this book we have described various types of microstructures and copolymer sequence distributions. But, given an unknown sample, how do you know what you’ve got? Even more embarrassing, you might have spent a considerable amount of time synthesizing a homopolymer or copolymer in an attempt to achieve a specific microstructure or copolymer distribution but it doesn’t have the properties you expected. How do you know the stuff at the bottom of your test tube is what you think it is? How do you measure its molecular weight? This last question will have to wait until after we discuss solution properties. In this chapter we consider the determination of chain microstructure using spectroscopic methods, focusing on infrared and nuclear magnetic resonance spectroscopy, the two most useful methods.
Objectives
Upon successfully completing this chapter you should:
- Be familiar with the fundamentals of spectroscopy, including simple harmonic motion, resonance and the nature of molecular transitions.
- Understand the nature of the transitions involved in infrared and NMR spectroscopy.
- Describe how these methods differ in their ability to perform quantitative analysis.
- Understand the nature and effect of spin-spin coupling in NMR.
- Be familiar with the application of IR and NMR to the characterization of polymer microstructure (branching, sequence isomerism, structural isomerism, tacticity in vinyl polymers, copolymer composition and copolymer sequence distributions).
- Understand some of the limitations and difficulties involved in the characterization of polymer microstructure by IR and NMR methods.
Self-Assessment Questions