Chapter 6: Study Guide and Self-Assessment
Ionomers such as Surlyn®, whose domain structure is illustrated schematically below, is an example of a copolymer, in this case a so-called random copolymer of ethylene and methacrylic acid (see CD). It is used to form the cut-proof” outer covering on golf balls (depends if you pull your ball into the road and hit passing traffic), which in our view makes it one of the key inventions of the 20th century. However, describing such copolymers as random” is not necessarily accurate. It is more precise to call them statistical copolymers, where the distribution of species in the chain depends upon the rate at which one monomer adds to an active site relative to the other. In this chapter we will discuss such copolymerizations using both the tools of kinetics and statistics developed in the preceding two chapters.
Objectives
Upon successfully completing this chapter you should:
- Understand the application of the kinetics of free radical copolymerization to the derivation of the copolymer equation.
- Be familiar with concept of reactivity ratios and the types of copolymers formed under certain limiting conditions.
- Be familiar with the various methods used to determine reactivity ratios.
- Understand the use of conditional probabilities to describe copolymer sequence distributions.
- Describe number fraction, run fraction and the parameter (a measure of the deviation from random statistics) using probability theory.
- Understand the nature of composition drift.
- Understand the difference between the terminal and penultimate model and how to test if data is consistent with one or the other of these models.
Self-Assessment Questions