Overview/Checklist

Overview

You now have a great toolbox of monomers and polymerization mechanisms by which you can make all sorts of exciting polymer materials! You can decide what sorts of monomers and polymerization mechanisms to use, when and how to control tacticity, and how polymerization mechanism impacts skeletal structure for both step growth and chain growth (radical, cationic, anionic, and ring opening). Let’s expand that breadth even more, and think about how we can mix monomers together to create copolymers. In Lesson 1, we learned the difference between homopolymer and copolymer, but most of the polymers we have actually talked about up until now have been homopolymers which incorporate a single type of monomer. In this Lesson, we learn how to predict the ratios in which a monomer will be incorporated into a polymer, and how that composition might drift over the course of a reaction.

Learning Outcomes

By the end of this lesson, you should be able to:

• Explain under what circumstances, and why, the composition of a polymer changes with extent of reaction
• Distinguish between homopropagation and cross propagation reactions
• Describe kinetics of binary chain copolymerization
• Define reactivity ratio
• Apply copolymer composition equations to predict polymer compositions
• Describe, in terms of reactivity ratios, the conditions leading to random copolymerization, azeotropic copolymerization; block copolymers, alternating copolymers, or homopolymers
• Interpret plots of F_A vs f_A
• Explain composition drift using reactivity ratios

Lesson Checklist

Please refer to the Canvas Calendar for specific timeframes.

Questions?

If you have questions, please feel free to post them to the General Questions and Discussion forum. While you are there, feel free to post your own responses if you, too, are able to help a classmate.