O N Ph N Ph O Ph Nan N Ph O Ph Dmf/ C M M
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Click Chemistry Combined with Nitroxide-Mediated Radical and Cationic Ring Opening Polymerization: A Versatile Method for Preparation of Well –Defined Block Copolymers Saber Ibrahim and Brigitte Voit, Institute for Polymer Research Dresden, Germany Introduction The azide/alkyne-“click”-reaction has had enormous impact within the field of polymer science. By using click chemistry not only more, but also more complex molecules and materials can be approached. Well-defined diblock copolymers consisting of polystyrene (PS) and poly (2-methyl-2-oxazoline) (PMeOX) or polyethyleneimine (PEI) were prepared using the nitroxide-mediated radical polymerization (NMRP) and Cationic Ring Opening Polymerization (CROP) methods respectively. The numberaverage molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed. N
N O m Ph
Ph o 125 C
Cl
N O
NaN 3
N
N n
Ph
N
m
m Ph
o
DMF/50 C
Cl
Prepared Polymer and Copolymer Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the α-terminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-bPMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethylenimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-b-PMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
Ph
N3
N3
N
N
AFM Pictures
PS
N
PMeOX
Thermal Analysis 100
6
80
Sab 22.001 Sab 29.001 Sab 30.001
60 40 4
(a)
(b)
20 0 -20
Deriv. Weight (%/°C)
O
Ph
Weight (%)
Ph
O
2 -40 -60 -80 -100
0
200
400
0 800
600
Universal V4.3A TA Instruments
Temperature (°C)
0.05
Sab22.001 Sab29.001 Sab30.001
Abkühlen
0.00
(c)
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-bPMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Heat Flow (W/g)
N
O
Ph
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability. • R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
Click Chemistry Combined with Nitroxide-Mediated Radical and Cationic Ring Opening Polymerization: A Versatile Method for Preparation of Well –Defined Block Copolymers Saber Ibrahim and Brigitte Voit, Institute for Polymer Research Dresden, Germany Introduction
The azide/alkyne-“click”-reaction has had enormous impact within the field of polymer science. By using click chemistry not only more, but also more complex molecules and materials can be approached. Well-defined diblock copolymers consisting of polystyrene (PS) and poly (2-methyl-2-oxazoline) (PMeOX) or polyethyleneimine (PEI) were prepared using the nitroxide-mediated radical polymerization (NMRP) and Cationic Ring Opening Polymerization (CROP) methods respectively. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed.
N O
O
N
N n
Ph
N
Ph
N
O
Ph
m Ph
Cl
N
PS
N
PMeOX
O Ph o 125 C
m
N3
N N
Ph
AFM Pictures
Cl
Ph
100
6
80
O
Sab 22.001 Sab 29.001 Sab 30.001
60 40 4
m Ph
(a)
Weight (%)
NaN3 o DMF/50 C
(b)
20 0 -20
Deriv. Weight (%/°C)
N
Thermal Analysis
2 -40 -60 -80 -100
N3
O n O
R
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-bPMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Universal V4.3A TA Instruments
N
Sab22.001 Sab29.001 Sab30.001
Abkühlen
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion
O
Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability.
N
m
Ph O R N
N n
N
N
N
N N
O
o
100 C KOH O
mN
Ph
O
N n
Heat Flow (W/g)
(c)
R N
N
0 800
600
0.00
O
RX
400
0.05
Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the αterminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2-Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-b-PMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethyleneimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-bPMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
a
200
Temperature (°C)
Prepared Polymer and Copolymer
N
0
N n
N
N
N
N N
• R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement
a) N-propargylpiperazine, 70 - 80 oC.
The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
PS PS-b-PMeox
4
5
6
7
8
9
Retention time
PS PS-b-PMeox
Preparation of polystyrene azide
4
5
6
7
8
polystyrene
9
Retention time
Hydrolysis of polystyrene-b-polymethyloxazoline O R N
Preparation of polymethyloxazoline alkyne O
N N
n-1
N
O
+
O
Polystyrene-b-polyethyleneimine N
N
n
+
Ph
N
m
N
Ph
Conversion %
Mn,cal
Mn, SEC
Mw, SEC
PDI
4 R N
n
5
O N
mN
N
6 N
N
Ph
7
Retention time
N N
O
100oC KOH
N
O
N
N
Ph
N3
Cu Catalyst
Monomer/ Initiator
N
O
O
O N n-1
O
N
N3
O O
mN
N
m
N
Cu Catalyst
N
n
N Ph
H R N H
N
mN
N
N
N N
PS-b-Meox
4
5
6
7 Retention time
8
9
10
8
9
Click Chemistry Combined with Nitroxide-Mediated Radical and Cationic Ring Opening Polymerization: A Versatile Method for Preparation of Well–Defined Block Copolymers Saber Ibrahim and Brigitte Voit, Institute for Polymer Research Dresden, Germany Introduction
The azide/alkyne-“click”-reaction has had enormous impact within the field of polymer science. By using click chemistry not only more, but also more complex molecules and materials can be approached. Well-defined diblock copolymers consisting of polystyrene (PS) and poly (2-methyl-2-oxazoline) (PMeOX) or polyethyleneimine (PEI) were prepared using the nitroxide-mediated radical polymerization (NMRP) and Cationic Ring Opening Polymerization (CROP) methods respectively. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed.
Size Exclusion Chromatograohy N O
O
N
N n
Ph
N
N
Ph
N3
4
5
6
7
8
9
Retention time
Ph
N
PS
N
EXP.
Monomer/ Initiator
Conversion %
Mn,cal
Mn, SEC
Mw, SEC
PDI
PSN3
309
83
6500
7400
8300
1.07
PMeox
200
79
5000
5800
6200
1.11
PS-b-PMeox
---
95
12000
12300
14100
1.14
PMeOX
O
O
m
PS PS-b-PMeox
N N
Ph
m Ph
AFM Pictures
Ph o 125 C
PMeox
Cl
Cl
N
Thermal Analysis
Ph
100
O
6
80
Sab 22.001 Sab 29.001 Sab 30.001
Ph
o
DMF/50 C
m
40
(a)
4
(b)
Weight (%)
NaN3
20 0 -20
Deriv. Weight (%/°C)
60
2 -40 -60 -80
N3
-100
O n O
R
N n
N
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-b-PMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Heat Flow (W/g)
(c)
Universal V4.3A TA Instruments
Sab22.001 Sab29.001 Sab30.001
Abkühlen
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion O
Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability.
N
m
Ph O R N
N n
N
N
N
N N
O
o
100 C KOH O
mN
Ph O
O
RX
0 800
600
0.00
R N
N
400
0.05
Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the αterminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2-Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-b-PMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethyleneimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-bPMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
a
200
Temperature (°C)
Prepared Polymer and Copolymer
N
0
N n
N
N
N
N N
• R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement
a) N-propargylpiperazine, 70 - 80 oC.
The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
N O m Ph
Ph o 125 C
Cl
N O
NaN 3
N
N n
Ph
N
m
m Ph
o
DMF/50 C
Cl
Prepared Polymer and Copolymer Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the α-terminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-bPMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethylenimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-b-PMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
Ph
N3
N3
N
N
AFM Pictures
PS
N
PMeOX
Thermal Analysis 100
6
80
Sab 22.001 Sab 29.001 Sab 30.001
60 40 4
(a)
(b)
20 0 -20
Deriv. Weight (%/°C)
O
Ph
Weight (%)
Ph
O
2 -40 -60 -80 -100
0
200
400
0 800
600
Universal V4.3A TA Instruments
Temperature (°C)
0.05
Sab22.001 Sab29.001 Sab30.001
Abkühlen
0.00
(c)
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-bPMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Heat Flow (W/g)
N
O
Ph
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability. • R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
Click Chemistry Combined with Nitroxide-Mediated Radical and Cationic Ring Opening Polymerization: A Versatile Method for Preparation of Well –Defined Block Copolymers Saber Ibrahim and Brigitte Voit, Institute for Polymer Research Dresden, Germany Introduction
The azide/alkyne-“click”-reaction has had enormous impact within the field of polymer science. By using click chemistry not only more, but also more complex molecules and materials can be approached. Well-defined diblock copolymers consisting of polystyrene (PS) and poly (2-methyl-2-oxazoline) (PMeOX) or polyethyleneimine (PEI) were prepared using the nitroxide-mediated radical polymerization (NMRP) and Cationic Ring Opening Polymerization (CROP) methods respectively. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed.
N O
O
N
N n
Ph
N
Ph
N
O
Ph
m Ph
Cl
N
PS
N
PMeOX
O Ph o 125 C
m
N3
N N
Ph
AFM Pictures
Cl
Ph
100
6
80
O
Sab 22.001 Sab 29.001 Sab 30.001
60 40 4
m Ph
(a)
Weight (%)
NaN3 o DMF/50 C
(b)
20 0 -20
Deriv. Weight (%/°C)
N
Thermal Analysis
2 -40 -60 -80 -100
N3
O n O
R
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-bPMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Universal V4.3A TA Instruments
N
Sab22.001 Sab29.001 Sab30.001
Abkühlen
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion
O
Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability.
N
m
Ph O R N
N n
N
N
N
N N
O
o
100 C KOH O
mN
Ph
O
N n
Heat Flow (W/g)
(c)
R N
N
0 800
600
0.00
O
RX
400
0.05
Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the αterminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2-Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-b-PMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethyleneimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-bPMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
a
200
Temperature (°C)
Prepared Polymer and Copolymer
N
0
N n
N
N
N
N N
• R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement
a) N-propargylpiperazine, 70 - 80 oC.
The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
PS PS-b-PMeox
4
5
6
7
8
9
Retention time
PS PS-b-PMeox
Preparation of polystyrene azide
4
5
6
7
8
polystyrene
9
Retention time
Hydrolysis of polystyrene-b-polymethyloxazoline O R N
Preparation of polymethyloxazoline alkyne O
N N
n-1
N
O
+
O
Polystyrene-b-polyethyleneimine N
N
n
+
Ph
N
m
N
Ph
Conversion %
Mn,cal
Mn, SEC
Mw, SEC
PDI
4 R N
n
5
O N
mN
N
6 N
N
Ph
7
Retention time
N N
O
100oC KOH
N
O
N
N
Ph
N3
Cu Catalyst
Monomer/ Initiator
N
O
O
O N n-1
O
N
N3
O O
mN
N
m
N
Cu Catalyst
N
n
N Ph
H R N H
N
mN
N
N
N N
PS-b-Meox
4
5
6
7 Retention time
8
9
10
8
9
Click Chemistry Combined with Nitroxide-Mediated Radical and Cationic Ring Opening Polymerization: A Versatile Method for Preparation of Well–Defined Block Copolymers Saber Ibrahim and Brigitte Voit, Institute for Polymer Research Dresden, Germany Introduction
The azide/alkyne-“click”-reaction has had enormous impact within the field of polymer science. By using click chemistry not only more, but also more complex molecules and materials can be approached. Well-defined diblock copolymers consisting of polystyrene (PS) and poly (2-methyl-2-oxazoline) (PMeOX) or polyethyleneimine (PEI) were prepared using the nitroxide-mediated radical polymerization (NMRP) and Cationic Ring Opening Polymerization (CROP) methods respectively. The number-average molecular weight and fraction of each segment were precisely controllable by adjusting the monomer/initiator ratio in feed.
Size Exclusion Chromatograohy N O
O
N
N n
Ph
N
N
Ph
N3
4
5
6
7
8
9
Retention time
Ph
N
PS
N
EXP.
Monomer/ Initiator
Conversion %
Mn,cal
Mn, SEC
Mw, SEC
PDI
PSN3
309
83
6500
7400
8300
1.07
PMeox
200
79
5000
5800
6200
1.11
PS-b-PMeox
---
95
12000
12300
14100
1.14
PMeOX
O
O
m
PS PS-b-PMeox
N N
Ph
m Ph
AFM Pictures
Ph o 125 C
PMeox
Cl
Cl
N
Thermal Analysis
Ph
100
O
6
80
Sab 22.001 Sab 29.001 Sab 30.001
Ph
o
DMF/50 C
m
40
(a)
4
(b)
Weight (%)
NaN3
20 0 -20
Deriv. Weight (%/°C)
60
2 -40 -60 -80
N3
-100
O n O
R
N n
N
(d)
Atomic Force Microscopy 2.0 μm images of polystyrene block poly2-methyl-2-oxazoline (PS-b-PMeox) with diffeent block ratios, (a) 1:6.7 & (b) 1:9.3 & (c) 1:0.9 and (d) 1:5.2
Heat Flow (W/g)
(c)
Universal V4.3A TA Instruments
Sab22.001 Sab29.001 Sab30.001
Abkühlen
-0.05
-0.10
-0.15
20
40
60
Exo Down
80
Temperature (°C)
100
120
140 Universal V4.3A TA Instruments
Conclusion O
Poly(alkoxyamine) including PMeOX segments can be used as a macroinitiator for NMRP of styrene. The strategy described here is available for the preparation of a wide variety of well-defined block copolymer libraries to be readily prepared in the minimum number of steps under synthetically robust conditions, and is expected as to be a powerful systematic screening tool for the preparation of interesting phase separated functional polymeric materials with specific metal binding ability.
N
m
Ph O R N
N n
N
N
N
N N
O
o
100 C KOH O
mN
Ph O
O
RX
0 800
600
0.00
R N
N
400
0.05
Polystyrene prepared by nitroxide-mediated radical polymerization bearing a benzyl chloride on the αterminus was converted to an azide by SN2 displacement. Piperazine was protected to afford its N-Boc derivatives. This reacted with propargyl bromide to obtain N-t-Boc propargylpiperazine, then Deprotected with trifluroacetic acid yielded propargyl piperazine. Poly2-methyl-2-Oxazoline was created by cationic ring opening polymerization and terminated with propargylpiperazine. Block copolymer PS-b-PMeOX was obtained by 1,3-dipolar cycloaddition reaction between azide group in PS and alkyne group in PMeOX in present of Cu(I)-catalyzed. Polystyrene-bpolyethyleneimine (PS-b-PEI) was synthesized by the hydrolysis of the obtained block copolymer PS-bPMeOX in alkaline medium overnight. The synthesis of diblock copolymers by combining predefined polymeric fragments via click chemistry was proved. In this situation, the fragments could be completely linked with each other and diblock copolymers obtained exhibited a narrow molecular weight distribution.
a
200
Temperature (°C)
Prepared Polymer and Copolymer
N
0
N n
N
N
N
N N
• R.K. O'Reilly, M.J. Joralemon, K.L. Wooley and C.J. Hawker, Chem Mater 17 (2005), 5976. • C.J. Hawker, V.V. Fokin, M.G. Finn and K.B. Sharpless, Aust J Chem 60 (2007), 381. • P.L. Golas and K. Matyjaszewski, QSAR Comb Sci 26 (2007),1116. • N.V. Tsarevsky, B.S. Sumerlin and K. Matyjaszewski, Macromolecules 38 (2005), 3558. • N.V. Tsarevsky, S.A. Bencherif and K. Matyjaszewski, Macromolecules 40 (2007), 4439. • H. Zheng, L.M. Weiner, O. Bar-Am, et al, Bioorg. & Med. Chem. 13 (2005), 773. • S. Fleischman, H. Komber, D. Appelhans, B. I. Voit, Macromol. Chem. Phys. 208 (2007), 1050.
Aknowledgement
a) N-propargylpiperazine, 70 - 80 oC.
The author would like to thank his colleague S. Fleishmann , L. Häußler for TG measurement and GPC experiments were performed by Frau P. Treppe. Also, We gratefully acknowledge financial support and participate for scholarship from the Egyptian Ministry for Scientific Research.
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