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

2. Living Polymerization (II) by Ru-Ke Bai
Department of Polymer Science and Engneering
University of Science and Technology of China

3. A Brief Review What are the major criteria for living polymerization?
What is living polymerization?
No termination
No chain transfer
What are the major criteria for living polymerization? Mn A
PDI
Block copolymers can be prepared by sequential addition of monomers. C B
Time
ln[M]0/[M]t
Living polymerization is a good tool for the preparation of block copolymers.

4. Rankings of Anions…
How to characterize the reactivity of a propagating anion?

5. Propagating Anions
pKa of conjugate acid
of prop.chain end 42 25 25 20

6. Propagating Anions 16-18 10-12 11-13 pKa of conjugate acid
of prop.chain end
16-18
10-12
11-13

7. Initiators Monomer pKa Useful Initiator Styrenes.dienes 42
RLi, NH2-, Ar -
Acrylates 25
RMgX, DPHL
Acrylonitriles
RO -, C5H5-
Vinyl ketones,
Aldehydes 20
RO -
Cyclic oxides
16-18
Siloxanes(-D3)
10-12
HO -, RO -
Cyano acrylates
11-13
H2O, HO -, RO -
Nitroalkenes 10
KHCO3, H2O
most nucleophilic
Super glue
Reactivity
Least nucleophilic

8. Microstructure of Dienes
Four different microstructures in polyisoprene
cis 1-4 isomer
(natural rubber)
trans 1-4 isomer
1-2 isomer
3-4 isomer
cis-1,4 favored in hydrocarbon solvents

9. Can MMA be polymerized via living process ?
Side reactions 1) 2) 3)

10. PMMA via Living Pzn PMMA homopolymer Can not use BuLi directly
Make new initiator (use 1,1-diphenylethylene)
1,1-diphenyl hexyl lithium
(DPHL)
Sterically hindered
resonant stabilization

11. PMMA via Living Pzn

12. Block Copolymers
Definition: Macromolecules consisting of homogenous segments made from different monomers (usually two or three different monomers).
Ex. A-A-A-A-A-A-B-B-B-B-B-B

13. Some Basic Diblock Copolymer Architectures
Linear Graft
Ex: PS-g-PI
Ex. PS-b-PI
Star

14. Microphase Separation
Most polymers are immiscible

15. Block Copolymer Uses Thermoplastic Elastomer Common Elastomer
Poly(cis-1,4-butadiene)
SBS (PS-PB-PS)
Physical crosslinking
Thermal reversibility
Can process it repeatedly
Sulfur
Crosslinking
heating
cooling
Chemical rosslinking
Thermal irreversibility
Can’t process it repeatedly

16. Self-Assembly of Block Copolymer Polym. Chem. 2011, 2, 1018–1028.
PB-b-PEO
PS-b-PAA
cryoTEM
micrographs
TEM micrographs
vesicles
Cylindrical
micelles
Spherical
micelles
= packing parameter, v = hydrophobic volume, a = interfacial area at the hydrophobe-hydrophile/water interface, = the chain length normal to the surface per molecule.

17. Dispersion of Carbon Nanotubes by Block Copolymer
The study of Single-Walled Carbon Nanotubes (SWNT) composite materials
has been hindered by the poor solubility and processibility of SWNTs.
PS-b-PAA has been used to stabilize SWNT and prevent their aggregation.
The micelle-encapsulated SWNTs are compatible with a wide variety of
solvent and polymer matrices, which can be used to produce carbon
nanotube materials.
Kang, Y. and Taton, A. T. J. Am. Chem. Soc. 2003, 125(19) 5650 – 5651.

18. Synthesis of Block Copolymers
A-B diblock or A-B-A triblock copolymers
same pKa, same reactivity; no problem
any order of addition, can cross over back & forth
2) ethylene oxide/styrene copolymers
styrene pKa= 42
epoxide pKa= 16-18
cross over from ethylene oxide not possible

19. 3) Styrene & MMA Styrene-MMA Block Copolymers Styrene
Then MMA, but can’t do sequential addition
Styrene

20. Styrene-MMA Block Copolymers
cap w/ 1,1-diphenylethylene (DPE)
-78 oC, THF

21. PMMA-PS-PMMA DFI to initiate styrene
Diphenyl ethylene to initiate MMA segment
Add MMA

22. Synthesis of Regular Star PS by Iterative Methodology Using DPE FunctionalityX = Y
1st Iteration 1
1st Iteration
( = )
(= )
( = )
1st Iteration
2st Iteration
3st Iteration
4st Iteration
5st Iteration

23. Synthesis of Asymmetric Star-Branched Polymers by Iterative Methodology1

24. Synthesis of Asymmetric Star-Branched Polymers by Iterative Methodology1

25. Synthesis of Star-Branched PS with up to 63 Arms by Iterative Methodology5

26. Branched Polymers with Complex Architectures
Macromol. Rapid Commun. 2010, 31,
star-linear-star
star-on-linear
(dendrimer)-linear-(dendrimer)
(dendrimer)-on-linear
graft-on-graft
graft-on-star
star-on-graft
star-on-star

27. Living/Controlled Free Radical Polymerization
How to perform a living free radical polymerization?
Anionic polymerization Radical polymerization
kt = kt =
Ri > Rp Ri < Rp
Reversible termination
Terminology:
“controlled/living”,
“pseudo-living”, “quasi-living”, and
“reversible deactivation radical polymerization”

28. Stable Free-Radical Polymerization
(SFRP)
TEMPO: 2,2,6,6-tetramethyl-1-piperidinoxyl
Radical was formed differently
Reversible chain termination!
M. K. Georges, et al, Macromolecules, 26, 2987( 1993).

29. Atom Transfer Radical Polymerization (ATRP)
X = Br , Cl
Components:
Monomer: A wide variety of monomers
Initiator: R-X, X = Br and Cl
Catalyst: Cu, Fe, and Ru etc.
Ligand: Bipyridine ect.
Radical was formed differently
Reversible chain termination!
Wang, J. S.; Matyjaszewski, K. Macromolecules 1995, 28,

30. Reversible Addition-Fragmentation Chain Transfer (RAFT)
Normal radical initiators (AIBN, etc.)
Reversible chain transfer!
Rizzardo, E., et al. Macromolecules 1998, 31,

31. Advantages of Living Free Radical Polymerization
Radical polymerization Anionic polymerization
A variety of monomers, including
the monomers with OH, COOH groups;
Perform in bulk, solution, emulsion,
and suspension systems;
Simple and inexpensive.
Styrenes, dienes, and methacrylates;
Perform in solution under unaerobic
and anhydrous conditions;
Complex and expensive.
A powerful platform for preparing a variety of well-defined polymers