Supporting information
Direct Synthesis of Ethylene-Acrylic Acid Copolymers by Insertion Polymerization
Thomas Rünzi, Dominik Fröhlich and Stefan Mecking*
Chair of Chemical Materials Science, Department of Chemistry, University of Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany
First publ. in: Journal of the American Chemical Society: JACS 132 (2010), 50, pp. 17690-17691
Materials and General Consideration. All manipulations of palladium complexes were carried out under an inert atmosphere using standard glovebox or Schlenk techniques.
Glassware was dried under vacuum before use. Toluene was distilled from sodium, diethylether and THF from sodium / benzophenone ketyl under argon. DMSO and methylene chloride were distilled from CaH2. Ethylene (99.95 %) supplied by Praxair, and propionic acid (> 99.5 %) and poly(acrylic acid) (Mw 250.000 g mol-1) supplied by Sigma-Aldrich were used as received. Prior to use, acrylic acid (99 %), supplied by Sigma Aldrich, was dried over MgSO4, distilled, degassed via freeze-pump-cycles and stored at 4 °C under an inert atmosphere. {(κ2-P,O)-2-[di(2-methoxyphenyl)-phosphine]benzenesulfonato}(dimethyl sulf- oxide) palladium(II)-methyl (1-dmso)1 and {(κ2-P,O)-2-[di(2-methoxyphenyl)phosphine]- benzenesulfonato} (chloro)palladium(II)-methyl (1-Cl)2 were prepared by reported procedures. NMR spectra were recorded on a Varian Unity INOVA instrument. 1H and 13C NMR (inverse-gated) chemical shifts were referenced to the solvent signal. High-temperature NMR measurements of copolymers were performed in 1,1,2,2-tetrachloroethane-d2 at 130 °C.
Molecular weights (Mn) and number average degrees of polymerization (DPn) were determined from the integrals of the repeat units vs. unsaturated endgroups in 1H NMR spectra. IR spectra were acquired on a Perkin-Elmer Spectrum 100 instrument with an ATR unit. Differential scanning calorimetry (DSC) was performed on a Netzsch DSC 204 F1 instrument at a heating rate of 10 K min-1. DSC data reported are determined from the second heating scan. Crystallinities were determined assuming a melt enthalpy of 293 J g-1 for 100 % crystalline polyethylene.3
Ethylene polymerization in the presence of propionic acid and ethylene-acrylic acid copolymerization. Polymerizations were carried out in a 250 mL stainless steel mechanically stirred (1000 rpm) pressure reactor equipped with a heating/cooling jacket supplied by a thermostat controlled by a thermocouple dipping into the polymerization mixture. A valve controlled by a pressure transducer allowed for applying and keeping up a constant ethylene pressure. Prior to a polymerization experiment, the reactor was heated under vacuum to the desired reaction temperature for 30 – 60 min and then back-filled with argon. A solution of toluene and propionic acid or acrylic acid, respectively, was cannula transferred into the reactor under an argon counter stream. The catalyst precursor was dissolved in dichloromethane (1 mL) and inserted by syringe to the reactor. Radical inhibitor 3,5-di-t- butyl-4-hydroxy-toluene (BHT) was added to the reaction mixture. The reactor was closed and a constant ethylene pressure was applied. After the desired reaction time, the reactor was rapidly vented and cooled to room temperature. The polymer was precipitated in 400 mL of methanol and isolated by filtration. After repetitive washing with methanol in order to remove unreacted acrylic acid and stabilizer, the polymer was dried in vacuum at 50 °C for 48 hours.
Note that this procedure would also remove any acrylic acid homopolymer possibly formed by free-radical polymerization.
Stoichiometric Insertion Studies
[P,O]PdCH(COOH)CH2CH3 1-Cl AgBF4
OH O 20
Pd-H species
H3CCH=CHCOOH
Figure S1. 1H NMR (25°C; CD2Cl2) stacked plots: Pd-Me (black); 2,1-insertion product (red); crotonic acid (green)
t = 0 s 300 s 600 s 900 s 1200 s 1500 s 1800 s 2100 s 2400 s 3000 s 3600 s 4200 s 4800 s 5400 s 6000 s 6600 s 7200 s 7800 s 9000 s 8400 s
4JHH 1.8 Hz
3JHH 6.9 Hz
3JHH 7.2 Hz
[Pd]
CH3
OH O H3C OH
O H
H
H H
4JHH
3JHH
3JHH
Figure S3. gCOSY-NMR spectrum (CD2Cl2, 25 °C) of the reaction mixture of 1-Cl and acrylic acid. Crotonic acid (green), 2,1-insertion product (red).
Figure S4. Time dependent conversion of 1-Cl/AgBF4 (black) to the 2,1-insertion product (red) and formation of crotonic acid (green) at 25 °C
0 2000 4000 6000 8000 10000
0,0 0,2 0,4 0,6 0,8 1,0 1,2
normalized to [1-Cl]t=0 = 1
t [s]
1-Cl
2,1-insertion product crotonic acid [β-H elimination]
Figure S5. Pseudo first-order plot of the insertion of acrylic acid into Pd-Me (left), first-order plot of the formation of crotonic acid at 25 °C
0 500 1000 1500 2000 2500
-3,5 -3,0 -2,5 -2,0 -1,5 -1,0 -0,5 0,0
ln (Pd-Me/Pd-Me0)
t [s]
kobs(25°C) = 14.1 x 10-4 s-1
0 2000 4000 6000 8000 10000
0,00 0,05 0,10 0,15 0,20 0,25
ln([C]/[Pd-Me0])
t [s]
kobs(25°C) = 2,2 x 10-5 s-1
Characterization of the copolymers:
OH O 1 2 3 4
5
CH3 S1
S2 S3
αδ+ δβ+ γδ+ OH
O a
b c
d e
f
g
h i CH(B1)
B1 h
Figure S6. 1H NMR spectrum (C2D2Cl4, 130 °C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1)
0.5 2.5
4.5 6.5
8.5 11.0
b
a,e -COOH h d
4 c i
3
Figure S7. gCOSY-NMR spectrum (C2D2Cl4, 130 °C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1)
Figure S8. 13C NMR spectrum (C2D2Cl4(s), 130 °C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1)
1 2 3
4 5
B1
S1
S2
αδ+
βδ+ γδ+
CH(B1)
s
f1 (ppm)
b
a,e h d
4
General procedure for deprotonation of ethylene-acrylic acid copolymers. Deprotonation of poly(ethylene-co-acrylic acid) was performed analogous to [4]. 100 mg of the copolymer were dissolved in 1.5 mL of toluene and 0.15 mL of n-butanol at 80 °C. The required amount of a 1 M NaOH solution (1 equiv. NaOH referred to acrylic acid moieties) was added and the two-phase mixture was stirred for 30 minutes. The solvent was largely removed in vacuum and 5 mL of freshly mixed toluene/n-butanol (10:1 v/v) were added. The reaction mixture was allowed to stir at 80 °C for 60 minutes. The distillation/redissolution procedure was repeated thrice. The polymer was then evaporated to dryness and was dried in vacuum.
IR absorbances for poly(ethylene-co-acrylic acid) with 3 mol-% incorporation and the according Na-ionomer (Figure 2):
ATR-IR (ν, cm-1) for poly(ethylene-co-acrylic acid): 2928, 2839, 1704, 1573, 720.
ATR-IR (ν, cm-1) for poly(ethylene-co-acrylate): 2926, 2852, 1557, 1467, 1414, 720.
Figure S9. 1H NMR spectrum (C2D2Cl4, 130 °C) of an ethylene/acrylic acid copolymer with 9.6 mol-% incorporation of acrylic acid (entry 2-3)
b
a,e h d -COOH
4 3
Figure S10. 13C NMR spectrum (C2D2Cl4, 130 °C) of an ethylene/acrylic acid copolymer with 9.6 mol-% incorporation of acrylic acid (entry 2-3)
Figure S11. top: 13C NMR spectrum (C2D2Cl4, 130 °C) of ethylene/acrylic acid copolymer
13
5
b a
4
3 2
αδ+ βδ+B1
S1
s
0 20 40 60 80 110
140 170
200 230
1 2
>CH(COOH)
-CH2- CD3OD C2D2Cl4
-C(O)OH
OH O
n OH O
Figure S12. Second scan DSC data for polyethylene (green) (entry 1-1), poly(ethylene-co- acrylic acid) with 3.0 mol-% incorporation (black), poly(ethylene-co-acrylic acid) with 6.4 mol-% incorporation (blue), poly(ethylene-co-acrylic acid) with 9.6 mol-% incorporation (red).
References
(1) Guironnet, D.; Roesle, P; Rünzi, T.; Göttker-Schnetmann, I.; Mecking, S. J. Am.
Chem. Soc. 2009, 131, 422-423.
(2) Rünzi, T.; Guironnet, D.; Göttker-Schnetmann, I.; Mecking, S. J. Am. Chem. Soc.
2010, 132, 16623–16630.
(3) Physical Properties of Polymers Handbook (Ed.: Mark, J. E.), Springer 2007, 2nd Edition.
(4) Vanhoorne, P.; Register, R. A. Macromolecules 1996, 29, 598-604.
Complete list of authors for reference 6:
Johnson, L.; Wang, L.; McLain, S.; Bennett, A.; Dobbs, K.; Hauptman, E.; Ionkin, A.; Ittel, S.; Kunitsky, K.; Marshall, W.; McCord, E.; Radzewich, C.; Rinehart, A.; Sweetman, K.J.;
Wang, Y.; Yin, Z.; Brookhart, M. ACS Symp. Ser. 2003, 857, 131-142.
