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Anionic Polymerization

Anionic Polymerization. By Chris Isely. 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.

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Anionic Polymerization

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  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.

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