1. Anionic Polymerization By Chris Isely

2. Benefits of Anionic Polymerization • It is one of the best ways to synthesize polymers with an exact structure and an exact molecular weight • Anionic Polymerization • Considered a living polymerization. • Therefore the process can be manipulated to achieve a desired molecular weight and structure.

3. Overview • Cleaning: Styrene Isoprene D3 • Polymerizing: Styrene Isoprene D3

4. Anionic polymerization • Anionic polymers must be contained in an anaerobic state because any contamination, such as oxygen, can cause the polymerization to terminate prematurely. • Initiated using sec-butyllithium. • Continue to propagate until terminated. • In our case • Terminated by adding methanol • The OH group will be the endpoint of the polymer.

5. Cleaning Styrene • Removed impurities from the commercial styrene • Required degassing by freezing with liquid nitrogen. • Added Dibutylmagnesium • Strong enough to remove contaminants, but not strong enough to initiate polymerization

6. Polymerizing Styrene • As with the purification, required strict no oxygen system. • When the styrene has been degassed, add the proper amount of sec-butyllithium. • Amount of initiator depended on the desired molecular weight.

7. Cleaning isoprene • Cleaned much the same way as styrene, however, isoprene had a lower boiling point and consequently had to be kept in an ice bath.

8. Cleaning D3 • D3 was dissolved in a cyclohexane solution and stirred over calcium hydride. • Monomer was then collected using vacuum distillation.

9. Polymerizing Isoprene and D3 • Both Isoprene and D3 could be added to the polymerized styrene. • As soon as they were added they would begin polymerizing, having a change in color.

10. Results • We made 8 triblock copolymerswith different volume fractions of Styrene, isoprene, and D3.

11. Future Work • Hydrogenation of the isoprene double bonds. • Sulfonation of the styrene.

12. Conclusion • Anionic polymerization, although difficult to conduct, is very useful for synthesizing triblock copolymers. • We used this process to create several samples, and our results were successful.

13. Acknowledgements • I want to thank Nacu and Dr. Cochran for letting me work in the lab this semester. • I have learned a lot from this experience, I appreciate this opportunity.