Macromolecules
ARTICLE
c. N-n-ButylglycineꢀNCA. This was obtained as a colorless oil, 70%,
bp 110ꢀ120 °C (0.30ꢀ0.35 mbar).
Poly(N-iso-butylglycine)25, P10. GPC (DMAc): Mn = 1.4 kg/mol
(^M = 1.20).
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1H NMR (500 MHz; CDCl3): δ = 0.95 (3 H, d, JH,H = 7.4 Hz,
1H NMR (500 MHz; CDCl3): δ = 0.78 (80 H, br, (CH3)2ꢀ
CHꢀCH2ꢀ), 1.81 (24 H, br, (CH3)2ꢀCHꢀCH2ꢀ), 3.23 (22 H, br,
(CH3)2ꢀCHꢀCH2ꢀ), 4.08 (25 H, br, ꢀCH2ꢀCOꢀ), 7.32 ppm (5 H,
br, C6H5ꢀ).
CH3ꢀC3H6ꢀ), 1.36 (2 H, m, CH3ꢀCH2ꢀC2H4ꢀ), 1.57 (2 H, m,
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C2H5ꢀCH2ꢀCH2ꢀ), 3.40 (2 H, t, JH,H = 7.4 Hz, C3H7ꢀCH2ꢀ),
4.08 ppm (2 H, s, NꢀCH2ꢀCOꢀ).
13C{1H}-NMR (125 MHz; CDCl3): δ = 13.50 (CH3ꢀC3H6ꢀ),
19.68 (CH3ꢀCH2ꢀC2H4ꢀ), 29.20 (C2H5ꢀCH2ꢀCH2ꢀ), 43.35 (C4),
48.84 (C3H7ꢀCH2ꢀ), 152.02 (C2), 165.52 ppm (C5).
N-IsobutylglycineꢀNCA. a. N-i-Butylglycine Hydrochloride. This
was obtained in 57%, mp 225 °C.
Preparation of Block Copolypeptoids. Poly[(Sar)50-b-(N-nPrGly)25],
P11. In a glovebox, 0.203 g (1.77 mmol) of sarcosineꢀNCA was weighed
into reaction vessel and 2.3 mL of dry benzonitrile was added. After
complete dissolution 3.9 μL of benzylamine (36 μmol) was added. The
reaction mixture was stirred at room temperature and under constant
pressure (20 mbar) for 31/2 h. For analytical investigations of the first
block, 40 μL were removed from the reaction mixture. Then 0.1242 g
(0.87 mmol) of N-n-propylglycineꢀNCA was weighed out and dissolved
in 0.87 mL benzonitrile. The solution was added to the reaction mixture of
the first block. Additional 5 h the reaction mixture was stirred under
constant pressure (20 mbar). The reaction mixture was precipitated into
diethyl ether and isolated block copolypeptoide was dried under reduced
pressure, dissolved in water and subsequently freeze-dried.
1H NMR (500 MHz; DMSO-d6): δ = 0.93 (6 H, d, 3JH,H = 6.7 Hz,
(CH3)2ꢀCHꢀCH2ꢀ), 2.02 (1 H, m, (CH3)2ꢀCHꢀCH2ꢀ), 2.77 (2 H,
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d, JH,H = 7.0 Hz, (CH3)2ꢀCHꢀCH2ꢀ), 3.82 (2 H, s, NHꢀ
CH2ꢀCOOH), 9.16 (2 H, br, NH HCl), 13.74 ppm (1 H, br, COOH).
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b. N-Benzyloxycarbonyl-N-isobutylglycine. This was obtained as a
colorless oil, 87%.
1H NMR (500 MHz; CDCl3): δ = 0.88 (6 H, m, (CH3)2ꢀ
CHꢀCH2ꢀ), 1.84 (1 H, m, (CH3)2ꢀCHꢀCH2ꢀ), 3.16 (2 H, m,
(CH3)2ꢀCHꢀCH2ꢀ), 4.03 (2 H, m, NꢀCH2ꢀCOOH), 5.15 (2 H, m,
C6H5ꢀCH2ꢀOꢀ), 7.31 ppm (5 H, m, C6H5).
GPC (DMAc): Mn = 5.7 kg/mol (^M = 1.13).
1H NMR (500 MHz; D2O): δ = 0.89 (51 H, br, CH3ꢀC2H4ꢀ), 1.50
(35 H, br, CH3ꢀCH2ꢀCH2ꢀ), 2.98 (135 H, br, CH3ꢀ), 3.29 (30 H,
br, CH3ꢀCH2ꢀCH2ꢀ), 4.26 (121 H, br, (CH3ꢀC2H4ꢀ)Nꢀ
CH2ꢀCOꢀ, (CH3ꢀ)NꢀCH2ꢀCOꢀ and NHꢀCH2ꢀC6H5), 7.33
ppm (5 H, br, C6H5ꢀ).
c). N-IsobutylglycineꢀNCA. This was obtained as a colorless solid,
70%, mp.: 39 °C
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1H NMR (500 MHz; CDCl3): δ = 0.96 (6 H, d, JH,H = 6.7 Hz,
(CH3)2ꢀCHꢀCH2ꢀ), 1.92 (1 H, m, (CH3)2ꢀCHꢀCH2ꢀ), 3.20
3
(2 H, d, JH,H = 7.5 Hz, (CH3)2ꢀCHꢀCH2ꢀ), 4.09 ppm (2 H, s,
1H NMR (500 MHz; CDCl3): δ = 0.88 (50 H, br, CH3ꢀC2H4ꢀ),
1.41 (33 H, br, CH3ꢀCH2ꢀCH2ꢀ), 2.96 (129 H, br, CH3ꢀ), 3.21 (32
H, br, CH3ꢀCH2ꢀCH2ꢀ), 4.27 (117 H, br, (CH3ꢀC2H4ꢀ)Nꢀ
CH2ꢀCOꢀ, (CH3ꢀ)NꢀCH2ꢀCOꢀ and NHꢀCH2ꢀC6H5), 7.28
ppm (5 H, br, C6H5ꢀ).
NꢀCH2ꢀCOꢀ).
13C{1H} NMR (125 MHz; CDCl3): δ = 19.80 ((CH3)2ꢀCHꢀ
CH2ꢀ),26.96((CH3)2ꢀCHꢀCH2ꢀ), 49.54 (C4),51.21((CH3)2ꢀCHꢀ
CH2ꢀ), 152.37 (C2), 165.45 ppm (C5).
Preparation of Homopolypeptoids. For the kinetic measurements
with IR spectroscopy and gas chromatography the polymerization
mixture was prepared and sealed in a glovebox under inert and dry
atmosphere.
Poly[(Sar)50-b-(N-nBuGly)25], P12. GPC (DMAc): Mn = 6.8 kg/mol
(^M = 1.16).
1H NMR (500 MHz; CDCl3): δ = 0.90 (38 H, br, CH3ꢀC3H6ꢀ),
1.30 (27 H, br, CH3ꢀCH2ꢀC2H4ꢀ), 1.47 (25 H, br, CH3ꢀ
CH2ꢀCH2ꢀCH2ꢀ), (16 H, br, C3H7ꢀCH2ꢀ), 3.03 (125 H, br, CH3ꢀ),
3.35 (23 H, br, CH3ꢀC2H4ꢀCH2ꢀ), 4.23 (105 H, br, (C4H9ꢀNꢀ
CH2ꢀCOꢀ and CH3ꢀNHꢀCH2ꢀC6H5), 7.29 ppm (5 H, br, C5H6-).
1H NMR (500 MHz; D2O): δ = 2.96 (122 H, br, CH3ꢀ), 4.28 (84 H,
br, (CH3ꢀNꢀCH2ꢀCOꢀ), 7.20 ppm (5 H, br, C6H5ꢀ).
Poly[(Sar)50-b-(N-iBuGly)25], P13. GPC (DMAc): Mn = 5.6 kg/mol
(^M = 1.09).
Exemplarily, the preparation of Poly(Sar)25 was performed as follows.
Poly(sarcosine)25, P1. SarꢀNCA (0.2647 g, 2.3 mmol) was weighed
into reaction vessel dissolved in 2.3 mL of dry benzonitrile and 0.228 g
(2.3 mmol) of NMP. After complete dissolution the reaction vessel was
closed with a septum. Outside of the glovebox the initiator benzylamine
(10 μL, 0.092 mmol) was added via a syringe ([M]0/[I]0 = 25). The
reaction mixture was stirred at room temperature under constant
pressure (20 mbar). After several hours the reaction mixture was
precipitated into diethyl ether and isolated POI was dried under reduced
pressure. The product was dissolved (or suspended for water insoluble
polymers) in water and subsequently freeze-dried.
1H NMR (500 MHz; TFA (DMSO-d6)): δ = 1.02 (63 H, br,
(CH3)2ꢀCHꢀCH2ꢀ), 2.07 (11 H, br, (CH3)2ꢀCHꢀCH2ꢀ), 3.22
(160 H, br, (CH3)2ꢀCHꢀCH2ꢀ) and CH3ꢀ), 4.55 (109 H, br,
((CH3)2ꢀCHꢀCH2ꢀ)NꢀCH2ꢀCOꢀ, (CH3ꢀ)NꢀCH2ꢀCOꢀ and
NHꢀCH2ꢀC6H5), 7.29 ppm (5 H, br, C6H5ꢀ).
GPC (DMAc): Mn = 1.3 kg/mol (^M = Mw/Mn = 1.31).49
1H NMR (500 MHz; D2O): δ = 2.89 (77 H, br, CH3ꢀ), 4.20 (55 H,
br, ꢀCH2ꢀCOꢀ), 7.28 ppm (5 H, br, C6H5ꢀ).
Investigation of Polymerization Kinetics. For the kinetic
investigations using IR spectroscopy or gas chromatography the monomer
solutions were prepared and sealed in a glovebox under inert and dry
atmosphere (<0.1 ppm of H2O) in custom-made Schlenk-tubes. The
initiator was added outside the glovebox after sampling [M]0 and was added
against dry nitrogen or argon flow via a septum. The polymerization kinetics
were determined following the decrease of the monomer concentration.
IR Spectroscopy. Polymerization kinetics were investigated by
ATRꢀFTIR spectroscopy by following the decrease of the intensity of
the CdO stretching band (≈1776 cmꢀ1) which responds linear with
the concentration in the investigated concentration range. Samples
(approximately 5 μL) were taken manually and during sampling inert
gas was blown over the reaction mixtures.
Poly(N-ethylglycine)25, P4. GPC (DMAc): Mn = 1.7 kg/mol (^M
=
1.25).
1H NMR (500 MHz; CDCl3): δ = 1.10 (73 H, br, CH3ꢀ), 3.40
(47 H, br, CH3ꢀCH2ꢀ), 4.17 (47 H, br, ꢀCH2ꢀCOꢀ), 7.25 ppm
(5 H, br, C6H5ꢀ).
Poly(N-n-propylglycine)25, P6. GPC (DMAc): Mn = 2.8 kg/mol
(^M = 1.20).
1H NMR (500 MHz; CDCl3): δ = 0.83 (79 H, br, CH3ꢀ), 1.62 (53
H, br, CH3ꢀCH2ꢀ), 3.18 (50 H, br, CH3ꢀCH2ꢀCH2ꢀ), 4.11 (50 H,
br, ꢀCH2ꢀCOꢀ), 7.20 ppm (5 H, br, C6H5ꢀ).
Poly(N-n-butylglycine)25, P8. GPC (DMAc): Mn = 2.3 kg/mol
(^M = 1.16).
Gas Chromatography. Online gas chromatographic measurement of
the monomer conversion was possible for all monomers but SarꢀNCA.
Polymerization mixtures were sampled at regular intervals automatically.
Monomer consumption was followed by the change of the ratio of the
integrals of the monomer and the internal standard over time.
1H NMR (500 MHz; TFA (DMSO-d6)): δ = 0.84 (65 H, br, CH3ꢀ),
1.29 (43 H, br, CH3ꢀCH2ꢀ), 1.62 (38 H, br, CH3ꢀCH2ꢀCH2ꢀ),
3.33 (43 H, br, CH3ꢀC2H4ꢀCH2ꢀ), 4.39 (41 H, br, ꢀCH2ꢀCOꢀ),
7.19 ppm (5 H, br, C6H5ꢀ).
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dx.doi.org/10.1021/ma201015y |Macromolecules 2011, 44, 6746–6758