Additional Monomers - Matyjaszewski Polymer Group - Carnegie Mellon University

ATRP of Additional Monomers

(Meth)acrylamides

4-Vinyl Pyridine

Dimethyl(1-ethoxycarbonyl)vinyl Phosphate)

2-Acrylamido-2-methyl-N-propanesulfonic acid

Methacrylic Acid


Poly(meth)acrylamides

(Teodorescu, M.; Matyjaszewski, K. Macromol. Rapid Commun. 2000, 21, 190-194.)

Controlled polymerization of (meth)acrylamides was achieved by ATRP using the initiating system methyl 2-chloropropionate/CuCl/tris(2-dimethylaminoethyl) amine. A linear increase of molecular weights with conversion and low polydispersity polymers (Mw /Mn = 1.2) were obtained in toluene, at room temperature, when N,N-dimethylacrylamide was used as the monomer. However, the polymerization reached limited conversion, which could be driven to higher conversion by increasing the catalyst/initiator ratio. The limited conversion is not due to the loss of the active chain end, but rather to the loss of activity of the catalytic system.

[DMAA]0 = 2.4 M; [MCP]0 = 23.7 mM; [CuCl] 0 = [Me6TREN] 0 = 47.4 mM; solvent = toluene; T = 20 oC. 

Conversion 79%, Mn 9,600; Mw /Mn = 1.2.

Poly(N-isopropylacrylamide) by ATRP in Solution

Coordination between the polymer/monomer and catalyst affects the level of control attained in the polymerization. Still under discussion whether it is chain end death or catalyst deactivation that stops the polymerization

NIPAM/EBriB/CuCl/CuCl2/Me6TREN

Time,

h

Conv.,

%

Mn,th

 

Mn SEC

 

Mw/Mn

 

100/1/3/0.6/3.6

1.5

26.8

3 000

16 600

1.03

500/1/5/0.25/5.25

2.5

49.2

27 800

68 800

1.14

1000/1/5/0.25/5.25

6.5

15.5

49.0

51.2

55 400

57 900

127 000

138 100

1.14

1.23

NIPAM/EBriB/CuCl/Me6TREN = 1000/1/10/10 in DMF 4 hr at 35 °C. 

Mn 73,000; Mw/Mn 1.19

Polymerization of 4-Vinyl Pyridine (4-VP) in Protic Media

(Xia, J.;  Zhang, X.; Matyjaszewski, K. Macromolecules 1999, 32, 3531-3533.

Tsarevsky, N. V.;  Braunecker, W. A.;  Brooks, S. J.; Matyjaszewski, K. Macromolecules 2006, 39, 6817-6824.)

Earlier work showed that CuCl/HMTETA served as an efficient catalyst for the aqueous ATRP of 4-VP. However, since the polymerization was carried out in the presence of CuCl2 and the polymerization yielded a polymer of narrow MWD, the polymerization was relatively slow, taking 30 h to reach ca. 80% monomer conversion.

Therefore, a more active catalyst, namely CuCl/TPMA should be used. (The following example details a preparation made as part of a kinetic study and more "normal" conditions employing non-deuterated reagents should also be used.)

A mixture of CD3OD (1.5 mL), D2O (1.5 mL), and 4VP (3 mL) was degassed by 6 freeze-pump-thaw cycles, the mixture was frozen in liquid nitrogen, the flask was filled with nitrogen, and a mixture of CuCl (0.0192 g, 0.194 mmol), CuCl2 (0.0133 g, 0.098 mmol, 30 % of the total Cu), and TPMA (0.0848 g, 0.29 mmol) was added quickly. The flask was then closed, evacuated and back-filled with nitrogen several times, and placed in a water bath thermostated at 30 oC. The nitrogen-purged MeOPEOBiB macroinitiator (MW = 699 g/mol, 0.162 mL) was then added. Samples were periodically withdrawn with a nitrogen-purged syringe, and were diluted with either CD3OD (NMR analysis) or 50 mM solution of LiBr in DMF (SEC analysis). Monomer conversion was determined by 1H NMR analysis and molecular weights by SEC using polySt standards for calibration. The results are presented in the following table. Polymers with monomodal MWD were obtained and the PDI values were even lower than with the best system studied so far (CuCl + CuCl2 / HMTETA), the ATRP of 4VP using CuCl + CuCl2/HMTETA as the catalyst

Sample

Time, h

% Conv. (NMR)

Mn g/mol

Mw/Mn

1

0.5

24.1

10,460

1.10

2

1

30.9

12,460

1.11

3

2.5

45.0

16,890

1.12

4

4.5

57.5

20,000

1.15

5

7

64.8

23,200

1.17


4-VP in Non-protic Media (DMF)

A mixture of DMF (3 mL) and 4-VP (3 mL, 28 mmol) was degassed by 10 freeze-pump-thaw cycles, the mixture was frozen in liquid nitrogen, and the flask was filled with nitrogen. The flask was opened and a mixture of TPMA (0.0848 g, 0.292 mmol), CuCl (0.0192 g, 0.194 mmol), and CuCl2 (0.0133 g, 0.098 mmol) was added. The flask was quickly closed with a rubber septum, evacuated and back-filled with nitrogen several times. The mixture was then allowed to thaw in a thermostated oil bath, and the nitrogen-purged initiator, MePEOBiB (MW = 699 g/mol (0.16 mL)) was injected. Conversions were determined by GC. The results are presented in the following table.

ATRP of 4VP in DMF using CuCl + CuCl2/TPMA as the catalyst at 40 oC.

Sample*

Time, h

% Conv. (GC)

Mn *

Mw/Mn *

1

2.75

13.8

6.74

1.07

2

6

28.9

8.89

1.07

3

20.5

48.1

14.40

1.11

4

32.75

55.6

16.45

1.12

* PolySty standards were used.


Dimethyl(1-ethoxycarbonyl)vinyl Phosphate) (DECVP)

(Huang, J.; Matyjaszewski, K. Macromolecules 2005, 38, 3577-3583.)

Poly(dimethyl(1-ethoxycarbonyl)vinyl Phosphate) with controlled molecular weight and relatively low polydispersity (PDI < 1.5) were obtained by conducting an ATRP initiated with ethyl 2-bromoisobutyrate (EBriB) in the presence of Cu(I)Cl/2,2¢-bipyridine (bpy).  A faster rate of polymerization and higher monomer conversion was obtained in the polymerization using either Cu(I)Cl/ N,N,N',N'',N''-pentamethyldiethylenetriamine (PMDETA) or Cu(I)Cl/1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) as the catalyst system.

Homopolymerization of DECVP: 

A typical ATRP was carried out as follows: DEVCP (1 g, 4.5 mmol), EBriB (6.7 µL, 0.045 mmol) and 2-butanone (1 mL) were added to a 10 mL dried Schlenk flask.   Bpy (14.1 mg, 0.09 mmol) and Cu(I)Cl (4.4 mg, 0.045 mmol) were added under N2 after the initial contents of the flask had been subjected to three freeze-pump-thaw cycles. After stirring for 10 minutes at room temperature (rt), the flask was placed in a thermostated oil bath at 70 °C.  Samples were taken to analyze the monomer conversion by 1H NMR and molecular weight by GPC at different time intervals during the polymerization.  The polymerization was stopped by cooling to rt and opening the flask to air.  The mixture was then dissolved in 10 mL acetone and passed through neutral alumina column.  The final pure product was obtained after precipitating in hexanes.

M/I/Cu/L = 100/1/1/2. Temp. 70 °C. Time 8 hr. % Conversion = 26%, Mn = 7,000;   Mn,th = 5,800; Mw/Mn = 1.50.


Preparation of Poly(2-acrylamido-2-methyl-N-propanesulfonic acid),  (P(AMPSA))

2-Acrylamido-2-methyl-N-propanesulfonic acid (AMPSA) (5 g, 24.2 mmol) was added to a 25 mL Schlenk flask and degassed for 30 minutes.  Degassed tributylamine (5.8 mL, 24.3 mmol) was added to turn the AMPSA into a salt, followed by degassed DMF (8 mL).  The mixture was stirred until the AMPSA dissolved, then degassed for 20 minutes.  The copper/ligand complex was prepared in a separate Schlenk flask.  CuCl (34.2 mg, 0.35 mmol) and bpy (114 mg, 0.73 mmol) were placed in a 10 mL Schlenk flask.  The flask was subjected to vacuum for 30 seconds, then flushed with nitrogen.  This process was repeated 4 times, in order to remove all the oxygen from the flask.  Degassed DMF (3 mL) was then added, and the mixture was stirred for 10 minutes, under nitrogen, in order to make the copper/ligand complex.  EBriB (18 ml) was added to the polymerization flask, and the mixture was degassed.  A 1 mL portion of the copper/ligand complex (11.4 mg CuCl, 38 mg bpy) was removed and added to the main reaction flask.  The mixture was degassed for 4 minutes, then lowered into a 60°C oil bath and heated for 41 hours. The polymer was diluted with 20 ml water. The polymer was dialyzed against water to remove the un-reacted monomer the solvent and the catalyst. The solution was then passed through Diowex ion exchange resin column providing poly(AMPSA) polymers of low polydispersity index (1.1-1.4). However, in all cases studied, the monomer conversion was limited to 10-15%. (DP ~30)

The best conditions were monomer:initiator:copper:ligand/300:1:1:0.7 with a 5% excess of TBA, with EBriB as initiator, CuCl as the metal, and bpy as the ligand.

The polydispersity from these materials was relatively low ~1.2, much lower than those for the polyAMPSA produced by RAFT (~1.5-1.6).

ATRP of methacrylic acid (MAA) in aqueous media (water-methanol = 1:1) using Cu(I)/Na2EDTDAA as the catalyst

(EDTDAA is ethylenedithiodiacetic acid)

(Matyjaszewski, K.; Tsarevsky, N. In U.S. 7332550)

Flask 1:  0.2395 g (0.94 mmol) of Na2EDTDAA in 2 ml of D2O. The solution was degassed by 5 freez/pump/thaw cycles and 0.0672 g (0.472 mmol) CuBr was added over the frozen solution. The flask was closed, evacuated and back-filled with nitrogen several times. A clear solution was formed after warming up the flask.

Flask 2: 4 ml of MAA (4.06 g, 0.047 mol) was dissolved in 2 ml of MeOH-d4. The solution was degassed by 5 freez/pump/thaw cycles.

The solution in flask 2 was added to the first one, and a heterogeneous solution was formed. Nevertheless the flask was immersed in a thermostated oil bath at 75oC and 250 μl of MePEGBiB was added. The results are summarized below.

Sample

Time, h

Conversion

Mn*

Mw/Mn*

Maa11-1

1.5

0.221

-

-

Maa11-2

4

0.383

10920

1.28

Maa11-3

9

0.583

15440

1.33

Maa11-4

21

0.826

17600

1.41

* 0.2 M NaNO3 in water as the eluent, PEO standards