Direct Synthesis of Ethylene-Acrylic Acid Copolymers by Insertion Polymerization

Transcription

1 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 Konstanz, Germany S1

2 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. DMS and methylene chloride were distilled from CaH 2. Ethylene (99.95 %) supplied by Praxair, and propionic acid (> 99.5 %) and poly(acrylic acid) (M w g mol -1 ) supplied by Sigma-Aldrich were used as received. Prior to use, acrylic acid (99 %), supplied by Sigma Aldrich, was dried over MgS 4, distilled, degassed via freeze-pump-cycles and stored at 4 C under an inert atmosphere. {(κ 2 -P,)-2-[di(2-methoxyphenyl)-phosphine]benzenesulfonato}(dimethyl sulfoxide) palladium(ii)-methyl (1-dmso) 1 and {(κ 2 -P,)-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 INVA instrument. 1 H and 13 C 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-d 2 at 130 C. Molecular weights (M n ) and number average degrees of polymerization (DP n ) were determined from the integrals of the repeat units vs. unsaturated endgroups in 1 H 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 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-tbutyl-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. S2

3 Stoichiometric Insertion Studies 1-Cl 20 AgBF 4 H [P,]PdCH(CH)CH 2 CH 3 Pd-H species H 3 CCH=CHCH 9000 s 8400 s 7800 s 7200 s 6600 s 6000 s 5400 s 4800 s 4200 s 3600 s 3000 s 2400 s 2100 s 1800 s 1500 s 1200 s 900 s 600 s 300 s t = 0 s Figure S1. 1 H NMR (25 C; CD 2 Cl 2 ) stacked plots: Pd-Me (black); 2,1-insertion product (red); crotonic acid (green) 4 J HH 3 J HH H 3 C H H H H CH 3 H 3 J HH H [Pd] 3 J HH 6.9 Hz 3 J HH 7.2 Hz 4 J HH 1.8 Hz Figure S2. Details of the 1 H NMR spectrum (Figure S1) showing the indicative resonances of crotonic acid and the 2,1-insertion product. S3

4 Figure S3. gcsy-nmr spectrum (CD2Cl2, 25 C) of the reaction mixture of 1-Cl and acrylic acid. Crotonic acid (green), 2,1-insertion product (red). 1,2 normalized to [1-Cl] t=0 = 1 1,0 0,8 0,6 0,4 0,2 1-Cl 2,1-insertion product crotonic acid [β-h elimination] 0, t [s] Figure S4. Time dependent conversion of 1-Cl/AgBF 4 (black) to the 2,1-insertion product (red) and formation of crotonic acid (green) at 25 C S4

5 0,0-0,5 0,25 ln (Pd-Me/Pd-Me 0 ) -1,0-1,5-2,0-2,5 k obs (25 C) = 14.1 x 10-4 s -1 ln([c]/[pd-me 0 ]) 0,20 0,15 0,10 k obs (25 C) = 2,2 x 10-5 s -1-3,0 0,05-3,5 0, t [s] t [s] 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 S5

6 Characterization of the copolymers: a b c H d e f g h h i 5 H CH(B1) S 1 S 2 S 3 γδ + αδ+ δβ + CH 3 B1 3 -CH b a,e hd 4 c i Figure S6. 1 H NMR spectrum (C2D2Cl4, 130 C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1) S6

7 4 b a,e h d f1 (ppm) Figure S7. gcsy-nmr spectrum (C2D2Cl4, 130 C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1) γδ + CH(B1) βδ + s 4 αδ + S 2 B1 S 1 Figure S8. 13 C NMR spectrum (C2D2Cl 4 (s), 130 C) of an ethylene/acrylic acid copolymer with 3.0 mol-% incorporation of acrylic acid (entry 2-1) S7

8 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 NaH solution (1 equiv. NaH 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, CH b a,e h d Figure S9. 1 H NMR spectrum (C2D2Cl4, 130 C) of an ethylene/acrylic acid copolymer with 9.6 mol-% incorporation of acrylic acid (entry 2-3) S8

9 3 2 s 4 5 b a αδ + βδ+ B1 S 1 Figure S C NMR spectrum (C2D2Cl4, 130 C) of an ethylene/acrylic acid copolymer with 9.6 mol-% incorporation of acrylic acid (entry 2-3) C 2 D 2 Cl 4 H 2 -C()H n CD 3 D H >CH(CH) 1 -CH Figure S11. top: 13 C NMR spectrum (C 2 D 2 Cl 4, 130 C) of ethylene/acrylic acid copolymer from entry 2-1; bottom: 13 C NMR spectrum (CD 3 D, 25 C) of poly(acrylic acid). S9

10 Figure S12. Second scan DSC data for polyethylene (green) (entry 1-1), poly(ethylene-coacrylic 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, (2) Rünzi, T.; Guironnet, D.; Göttker-Schnetmann, I.; Mecking, S. J. Am. Chem. Soc. 2010, 132, (3) Physical Properties of Polymers Handbook (Ed.: Mark, J. E.), Springer 2007, 2 nd Edition. (4) Vanhoorne, P.; Register, R. A. Macromolecules 1996, 29, 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, S10