Transcript Supported Atom-Transfer Radical Polymerization and Its

Atom Transfer Radical
Polymerization (ATRP):
Concept, Application, Challenges and
Future Development
Youqing Shen
Departments of Chemical Engineering and
Materials Science and Engineering
McMaster University
Hamilton, Ontario, CANADA L8S 4L7
Mn
[M]0
Mn=
Conversion
• Mn
• Structure
[I]0
 Mm  Conv.
Radical reactions
P1
P2
P1 + P2
P1 + P2
P
+ M
P + M
P
+ S
P + S
P
+ Px
P + Px
?
Suppressing radical termination
Rt/Rp =kt [P•]2/kp[M][P•]
=kt[P•]/kp[M]
ATRP Mechanism
CuBr/L + Br P
CuBr2/L + P
Ligand
M
Cu
ATRP Systems
Metal
Ligand
CuBr, CuCl
Bipyridine
Initiator
X
Multidentate amine
RuBr2
PPh3 + Al(OiPr)3
FeBr2
PPh3
NiBr2
PPh3
PdBr2
PPh3
O
X
O
O
O
X
SO2Cl
2. ATRP Applications
A: Synthesis of polymers with controlled molecular weight
A: PS standard
B: PS by ATRP
C: PS by AIBN
Patten, T.E., Xia, J, Abernathy, T., Matyjaszewki, K. Science 1996, 272, 866.
Factors affecting the molecular
weight control
• Fast initiation
Narrow
• Rapid deactivation
MWD
C-XInitiator  C-Xpolymer
Initiator matches Monomer
X
O
O
X
O
SO2Cl
O
X
O
O
Br
O
O
O
O
Rapid deactivation
Mw
Mn
Kd
=
=
2
1
1 +
Kd[CuX2] Conv
Kp[R-X]
[CuX2][P ]
[CuX][P-X]
Kp - Temperature
Conv.-can not go too high
B: Synthesis block copolymers
Macroinitiator method
R-X + M1
CuX/L
X
CuX/L
M2
X
AB
X-R-X+ M1 CuX/L
X
X
CuX/L M 2
X
X
ABA
C: Synthesis of star polymers
Br
Br
O
O
O
Br
O
O
O
O
Br
O
O
O
O
Br
O
O
Br
O
Br
Matyjaszewski, K., Miller, P. J. Pyun, J. Kickelbick, G. Diaamanti,
Macromolecules 1999, 32, 6526
D: Hyperbranched Polymers
O
O
O
O
Cl
O
O
O
Br
Monomer-Initiator
O
Br
*
*
*
*
*
*
*
*
*
*
A
B*
A
B*
A
B
A*
A*
*
*
*
*
*
*
*
*
*
*
*
B*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
**
*
*
*
*
*
E. Synthesis of End-functionalized
Polymers
O
St, MMA, MA
Br
HO
O
O
St, MMA
Br
O
O
MA (at low conversion)
O
Cl
Cl
O
NH
Cl
O
Cl
O
St
MMA
Challenges for ATRP
Low catalyst
efficiency
High catalyst
residual
Deep color in
product
Purification
Catalyst and
ligand waste
Solution to the Problem ?
• Catalyst supporting
Mn and PDI vs conversion in MMA
polymerization by supported catalysts
3
15000
PS
or
Si
10000
2
5000
Mw/Mn
Mn
2.5
N
N
Cu
Br
1.5
Theor. Mn
1
0
0
20
40
60
80
Conversion (%)
Haddleton,
Chem. Commun. 1999, 99.
WHY?
Mw
Mn
=
2
1
1 +
Kd[CuX2] Conv
Kp[R-X]
Future development
Develop high reactive catalysts
Catalyst
Concentration.
Catalyst
residual
Color