Macromolecules
Article
(ramp 10050). The rotor spin rate was 13 kHz, with delay time of 3−
6 s. Adamantane was used as an external standard for 13C NMR and
octakis(trimethylsiloxy)silsesquioxane for 29Si NMR. Elemental
analysis was performed with a Leco 900 CHN analyzer. Films were
compression-molded at 70 °C 24 h in a Teflon form (3 cm × 1 cm ×
0.1 cm) which was held with a vice. Microscope images were recorded
under polarized light using an Olympus BX60 microscope equipped
with a Sony CCD-Iris color camera. Size exclusion chromatography
(SEC) measurements in tetrahydrofuran (THF) were performed with
a PSS (Polymers Standards Service) system, which included a
Viscotek VE1121 pump, a Shodex refractive index detector, a PSS
SLD 7000 multiangle light scattering detector, and styrene−
divinylbenzene copolymer columns (PSS SDV) at a rate of 1 mL
min−1. A linear polystyrene standard was used for calibration, which
causes deviations from expected molecular masses. UV−vis trans-
mission spectra were recorded on a Lambda 750 instrument
(PerkinElmer Inc., USA) equipped with a 100 mm integrating sphere
from 500 to 248 nm with a 4 nm increment on 1 mm cuvettes with a
drop-cast film of the sample. Rheological measurements were carried
out on an Anton Paar Physica MCR 301 rheometer equipped with a
CTD450 convection oven. Thin films (500 μm thick, 25 mm
diameter) of the samples were compression-molded in a heatable
press (Specac, 60 °C, 2 t, 1 min, baking paper for separation) and
measured in oscillation mode using the PP25 measuring system with
25 mm plate diameter and a plate-to-plate distance of 0.5 mm. The
measurements were conducted in the temperature range where the
materials are present as a melt. The measurement starts at 70 °C; the
temperature was increased to 120 °C, held for 1 h, and subsequently
decreased to 70 °C. This temperature was held constant until the
sample solidifies. STEM measurements were performed on a cold
field emission gun TEM/STEM (JEOL JEM-ARM 200F) instrument,
operated at an accelerating voltage of 200 kV and equipped with a
STEM Cs corrector (CESCOR; CEOS GmbH Heidelberg). Images
were obtained using a high angle annular bright-field (ABF) detector
with a camera length of 8 cm. The sample was prepared by the
ultramicrotomy technique with a thickness of about 20 nm and put on
a copper grid coated with thin pure carbon holey film.
ν(CO)); 1551 (s, amide II ν(C−N) with contributions of δ(N−
H)); 1443 (m, δ(C−H)); 1294 (s, ν(C−O−C)) cm−1.
2-(4-Butylureido)ethyl Methacrylate (3). 2-Isocynatoethyl meth-
acrylate (1 g, 6.44 mmol) was dissolved in absolute dichloromethane
(30 mL), and n-butylamine (0.47 g, 0.64 mL, 6.44 mmol) was added
dropwise. The colorless precipitate was filtered off and dried in vacuo.
1
Yield: 1.47 g (6.44 mmol, 100%). H NMR (400 MHz, CDCl3): δ
6.19−6.07 (m, 1H, H1), 5.64−5.53 (m, 1H, H1), 4.68 (s, 1H, H9 or
H11), 4.44 (s, 1H, H1, H9 or H11), 4.24 (t, J = 5.4 Hz, 2H, H6), 3.50
(q, J = 5.4 Hz, 2H, H8), 3.18−3.11 (m, 2H, H12), 1.94 (s, 3H, H4),
1.52−1.42 (m, 2H, H13), 1.41−1.27 (m, 2H, H15), 0.91 (t, J = 7.3
Hz, 3H, H16). 13C NMR (75 MHz, CDCl3): δ 167.73 (C5), 158.12
(C10), 136.22 (C2), 126.11 (C1), 64.37 (C6), 40.54 (C8), 39.88
(C12), 32.38 (C13), 20.15 (C4), 18.44 (C15), 13.89 (C16). CHNtheo
(C10H11NO4): C: 57.87; H: 8.83; N: 12.27. CHNexp: C, 57.78; H,
8.57; N, 12.23. IR: ν = 3336 (w, ν(N−H)); 2964, 2931, 2858 (m,
ν(C−H)); 1708 (s, ν(CO)); 1618 (s, amide I ν(CO)); 1574 (s,
amide II ν(C−N) with contributions of δ(N−H)); 1446 (m, δ(C−
H)); 1292 (s, ν(C−O−C)) cm−1.
2-(2-Hydroxyethyl)-3a,4,7,7a-Tetrahydro-1H-4,7-epoxyisoin-
dole-1,3(2H)-dione (4). A solution of 4,7,7a-tetrahydro-4,7-epoxyiso-
benzofuran-1,3-dione (10 g, 60.3 mmol) in methanol (250 mL) was
purged with nitrogen for 10 min in an ice bath. Subsequently,
ethanolamine (4 mL, 60.3 mmol) and triethylamine (6.10 g, 8.4 mL,
60.3 mmol) were added. The reaction mixture was allowed to warm
up, and the temperature was increased to 70 °C for 20 h.
Subsequently, ethanolamine (0.4 mL, 6.0 mmol) was added, and
stirring was continued for 2 h at 70 °C. The solution turned pale
yellow. After cooling to room temperature, the solution volume was
reduced and stored at −18 °C. The precipitate was collected by
vacuum filtration washed with isopropanol and used without further
purification. Dissolving the solid in isopropanol and storing it at −18
°C leads to crystalline 4. Yield: 10.72 g (51.25 mmol, 85%). 1H NMR
(300 MHz, CDCl3): δ 6.53−6.48 (m, 2H, H1&2), 5.27 (t, J = 0.9 Hz,
2H, H3&6), 3.79−3.72 (m, 2H, H14), 3.71−3.63 (m, 2H, H13), 2.88
(s, 2H, H4&5), 2.37 (s, 1H, H15). 13C NMR (75 MHz, CDCl3): δ
176.92 (C7/9), 136.67 (C1/2), 81.15(C3/6), 60.57 (C14), 47.65
(C4/5), 41.97 (C13). CHNtheo (C10H11NO4): C: 57.41; H: 5.30; N:
6.70. CHNexp C: 57.85; H: 5.56; N 6.72.
Synthesis. 3-Acetylaminopropanol (1).23 A mixture of isopro-
penyl acetate (25.97 g, 28.57 mL, 259.36 mmol) and 3-amino-
propanol (5.0 g, 5.1 mL, 64.84 mmol) was heated at 60 °C for 3 h in a
sealed vial. After the reaction was finished the residual isopropenyl
acetate and acetone were distilled off under vacuum. The product was
obtained as a yellow oil and used without further purification to
synthesize 2. Yield: 7.60 g (64.84 mmol, 100%). 1H NMR (300 MHz,
CDCl3): δ 6.80 (s, 1H, H8 or H4), 4.12 (1H, H8 or H4), 3.58 (t, J =
5.7 Hz, 2H, H1), 3.32 (td, J = 6.0 Hz, 2H, H3), 1.93 (s, 3H, H7), 1.63
(quint, 2H, H2). 13C NMR (75 MHz, CDCl3): δ 171.64 (C5), 59.40
(C1), 36.56 (C3), 32.05 (C2), 23.03 (C7).
Furfuryl methacrylate (FMA) (5)24 and 2-(1,3-dioxo-3a,4,7,7a-
tetrahydro-1H-4,7-epoxyisoindol-2(3H)-yl)ethyl methacrylate
(MIMA, 6)25 were synthesized according to literature procedures.
NMR and IR spectra can be found in SI2.
General Procedure for the Synthesis of Copolymers P1−P3 via
ATRP. BMA (100 equiv, 13.86 mL, 86.0 mmol), FMA (1.34 g) or
MIMA (2.49 g) each 10 equiv (8.6 mmol), according to the polymer,
and anhydrous toluene (54 mL) were mixed under an argon
atmosphere. The mixture was degassed using four freeze−pump−
thaw cycles. To the frozen mixture CuBr (1 equiv, 124 mg, 0.86
mmol) and HMTETA (1 equiv, 224 μL, 0.86 mmol) were added, and
another two vacuum−argon cycles were performed. The reaction was
carried out after addition of degassed EBiB (1 equiv, 126 μL, 0.86
mmol) by heating the mixture at 70 °C for 16 h. The polymers (listed
in Table 1) were purified by passing the solution through an alumina
3-Acetamidopropyl Methacrylate (2). To a stirred solution of 3-
acetylaminopropanol (1) (7.60 g, 64.84 mmol, 1.0 equiv) and
triethylamine (7.87 g, 10.94 mL, 77.81 mmol, 1.2 equiv) in anhydrous
CH2Cl2 (170 mL) a solution of methacryloyl chloride (8.13 g, 77.81
mmol, 1.2 equiv) in anhydrous CH2Cl2 (20 mL) was added dropwise
at 0 °C. After complete addition, the mixture was allowed to warm to
room temperature and stirred overnight. The orange slurry was
concentrated to half of the volume, cooled to 0 °C, and filtered; the
filtrate was extracted with water (2 × 25 mL). Afterward, the organic
phase was separated, dried over MgSO4, and concentrated in vacuo.
The crude product was obtained as an orange oil. After purification
via distillation in vacuo (132 °C, 7 × 10−3 mbar) pure 2 could be
Table 1. Polymers Prepared via ATRP
polymer
yield [%] dSF [%] dSM [%] dSH [%] PDI
P1
P2
P3
pBMA
FMAcoBMA
MIMAcoBMA
84
85
60
−
8.33
−
−
−
−
−
−
6.0
1.52
1.66
2.40
1
obtained as a colorless oil. Yield: 10.77 g (58.13 mmol, 90%). H
NMR (300 MHz, CDCl3): δ 6.14−6.02 (m, J = 1.5, 1.0 Hz, 2H, H12,
and H4), 5.58−5.50 (m, 1H, H12), 4.18 (t, J = 6.0 Hz, 2H, H1), 3.28
(td, J = 6.0 Hz, 2H, H3), 1.95 (s, 3H, H7), 1.92−1.90 (m, 3H, H13),
1.85 (quint, J = 6.0 Hz, 2H, H2). 13C NMR (75 MHz, CDCl3): δ
170.34 (C5), 167.65 (C9), 136.24 (C11), 125.83 (C12), 62.26 (C1),
36.47 (C3), 28.79 (C2), 23.31 (C7), 18.35 (C13). CHNtheo
(C9H15NO3): C, 58.36; H, 8.16; N, 7.56. CHNexp: C, 57.68; H,
8.10; N, 7.22. IR: ν = 3290 ν(N−H), w; 3088 ν(N−H) w; 2960,
2931, 2871 (m, ν(C−H)); 1716 (s, ν(CO)); 1639 (s, amide I
column (active, neutral) to remove the catalyst. The polymers were
precipitated from concentrated THF solution two times in ice-cold n-
hexane and dried at room temperature under reduced pressure. Parts
of the polymer samples were analyzed by SEC and 1H NMR to
determine the molar mass and molar mass distribution.
P1. H NMR (300 MHz, CDCl3): δ 4.10−3.82 (m, 1H, OCH2),
2.14−0.59 (m, 6H, pBMA backbone). IR: ν = 2958, 2931, 2874 (m,
1
C
Macromolecules XXXX, XXX, XXX−XXX