1. Odian Book
Chapter 3-15, 5-3

2. Living Polymerization

3. Living Polymerization
Neutral and Highly Reactive or

4. Living Polymerizations
Living polymerizations are chain growth polymerizations which proceed in the absence of irreversible chain transfer and termination steps.*
Diagnostic Characteristic of Living Polymerizations
The reaction proceeds until all monomer is consumed. If more monomer is introduced then the polymerization will continue
The number average molecular weight, Mn, is a linear function of conversion.
The number of propagating chains (active centers) is constant and independent of conversion.
Mn can be controlled by the reaction stoichiometry.
Sequential monomer addition results in the preparation of block copolymers.
Resulting polymers will exhibit a narrow molecular weight distribution and the polymer must exhibit a Poisson distribution in molecular weight.**
* Szwarc, M., Nature, 1956, 178, 1168.
** Flory, P. J., J. Am. Chem. Soc., 1940, 62, 1561.

5. Living Polymerization
No termination or chain-transfer side reaction during polymerization
Control of molecular weight
Mn=
Narrow molecular weight distribution
Synthesis of block copolymers by sequential monomer addition
Control of polymer chain microstructure
End-group functionalization
grams of monomer
Moles of initiator

6. Initiation
Nucleophilic Initiation of Vinyl Monomers

7. Anionic Polymerization of Styrene

8. Anionic Polymerization of Styrene

9. Anionic Polymerization of Styrene

10. Anionic Polymerization of Styrene

11. Initiators: Organolithiums
Soluble in hydrocarbons
Direct nucleophilic attack
No electron transfer
(RLi)N N= 6,4,2
MW=
g of monomer
moles of initiator

12. The Poisson Distribution in Molecular Weight
The constraints imposed on a living polymer require that the polymer exhibit a Poisson distribution in molecular weight.*

13. Scale of “Livingness”
Conversion should be linear with time in semi-logrithmic coordinates
Deceleration indicates termination or deactivation of catalyst.
When chain termination cannot be completely suppressed (kt > 0):
deviation from living behavior becomes more pronounced with time
The degree to which a reaction deviates at time, t, is proportional to the ratio of the rate of propagation to termination.

14. End Group Functionalization
Carboxylic acid terminated:
Primary alcohol terminated:

15. End Group Functionalization

16. Monomers Generally olefin w/ EWG or delocalizing groups
Methyl acrylate (MA)
Methyl methacrylate (MMA)
t-Butyl methacrylate (tBuMA)

17. Ion Pair Aggregation
Need to stabilize propagating anions

18. Ion Pair Aggregation
Need to stabilize propagating anions