Macromolecules
Article
(Py, AR) were predried over calcium hydride and distilled under
reduced pressure.
The fullerene diol monomer 4 was synthesized according to the
synthetic route in Scheme 1. [60]Fullerenoacetic acid 1 and 3,5-
bis(hydroxymethyl)phenyl 6-azide hexyl ether 3 were synthesized
using the same procedure as our previous work.41
pure samples were obtained by recrystallization of the crude product in
hexane three times.
Synthesis of Fullerene Polyesters. All the polymerization reactions
were conducted under nitrogen. A typical experimental procedure for
the synthesis of polyesters is given below: into a 10 mL Schlenk tube
equipped with a magnetic stirrer were placed fullerene diol monomer 4
(315 mg, 0.261 mmol), dicarbonyl chloride (0.261 mmol), and
pyridine (49.6 mg, 0.627 mmol) in the mixed solvent of o-DCB (3.2
mL) and DMAc (0.8 mL) at room temperature. The reaction mixture
was allowed to slowly warm up to 80 °C and was stirred at this
temperature for 48 h. The polyesters were obtained by precipitating in
methanol and purified by being dissolved in 1,2-dichlorobenzene and
precipitated in THF to obtain dark red solid. Yield: P1, 63%; P2, 78%;
P3, 58%; P4, 51%.
Synthesis of 10-Undecyn-1-yl [60]Fullerenoacetate (2). [60]-
Fullerenoacetic acid 1 (0.498 g, 0.640 mmol) was dissolved in the
mixed solvent of o-DCB (20 mL) and DMF (1 mL). Then PTSA
(0.122 g, 0.640 mmol), DMAP (0.078 g, 0.64 mmol), DIPC (0.121 g,
0.96 mmol), and 10-undecyn-1-ol (0.108 g, 0.640 mmol) were added
into the solution. The mixture was stirred for 1 h at room temperature.
Afterward, the mixture was filtered, and the filtrate was washed with
distilled water (50 mL × 3). The organic phase was dried over
anhydrous sodium sulfate, and the crude product was purified by silica
gel column chromatography using carbon disulfide as eluent. The
product was precipitated in methanol, filtered, and dried in a vacuum
Instrumentation. 1H NMR, 13C NMR, and 1H DOSY NMR
experiments were conducted on Agilent Technologies 600 MHz DD2
spectrometer with PFG 1H/19F/X probe at 25 °C, using d-chloroform
as the solvent and tetramethylsilane (TMS) as an internal standard.
For measurements of the self-diffusion coefficient, the solution
concentration was 1.0 mg/mL, and a DBPPSTE_CC (DOSY Bipolar
Pulse Pair Stimulated Echo with Convection Compensation) sequence
was used. Diffusion attenuation curves were obtained at a sequential
15-step linear increase of the amplitude of the magnetic field gradient
pulse in the range from 2.07 to 51.7 G/cm at fixed values of diffusion
time Δ, δpulse gradient pulse duration (2.0 ms), and relaxation time d1
(1 s). DOSY spectra were processed by Agilent’s VnmrJ 3.2 software.
Matrix-assisted laser desorption/ionization time-of-flight (MALDI-
TOF) mass spectrum was acquired on a Bruker Ultraflex-Treme
TOF/TOF mass spectrometer (Bruker Daltonics, Inc., Billerica, MA)
equipped with a Nd:YAG laser (355 nm). trans-2-[3-(4-tert-
Butylphenyl)-2-methyl-2-propenylidene]malononitrile (DCTB, Al-
drich, >99%) was served as matrix and prepared in CHCl3 at a
concentration of 20 mg/mL. Sodium trifluoroacetate (CF3COONa)
was served as cationizing agent and was prepared in ethanol at 10 mg/
mL. The sample was dissolved in CHCl3 at a concentration of 10 mg/
mL. The matrix and CF3COONa were mixed with the ratio of 10/1
(v/v). The sample preparation involved depositing 0.5 μL of matrix
and salt mixture on the wells of a 384-well ground-steel plate, allowing
the spots to dry, depositing 0.5 μL of the sample on a spot of dry
matrix, and adding another 0.5 μL of matrix and salt mixture on top of
the dry sample. After evaporation of the solvent, the plate was inserted
into the MALDI source. The mass scale was calibrated externally using
the peaks obtained from peptide standard at the molecular weight
range under consideration. Data analysis was conducted with Bruker’s
flexAnalysis software.
1
oven to yield a brown solid 2 (0.45 g, 75%). H NMR (600 MHz,
CDCl3), δ (ppm): 4.79 (s, 1H, H at the bridging C), 4.46 (t, 2H,
COOCH2), 2.19 (m, 2H, COOCH2CH2), 1.94 (t, 1H, −CCH),
1.87 (m, 2H, CH2CCH), 1.52 (m, 4H, COOCH2CH2CH2 and
CH2CH2CCH), 1.35 (m, 8H, CH2CH2CH2CH2CH2CH2CCH).
Synthesis of 9-(1-(6-(3,5-Bis(hydroxymethyl)phenoxy)-1-hexyl)-
1H-1,2,3-triazol-4-yl)-1-nonyl [60]Fullerenoacetate (Fullerene Diol
Monomer 4). Into a 250 mL two-necked round-bottom flask, 2 (0.965
g, 1.04 mmol), 3 (0.291 g, 1.04 mmol), and chloroform (80 mL) were
added and stirred for 10 min. A solution of CuSO4·5H2O (0.030 g,
0.12 mmol) in 20 mL of distilled water was added into the flask,
followed by the adding of sodium ascorbate (0.063 g, 0.32 mmol)
under a nitrogen atmosphere. The mixture was stirred for 3 days at
room temperature under a nitrogen atmosphere. The organic phase
was washed with distilled water (100 mL × 3) and dried over
anhydrous sodium sulfate. After filtration, the crude product was
purified by column chromatography using carbon disulfide/ethyl
acetate (1/1, v/v) as eluent, and the purified sample was obtained by
being dissolved in chloroform and precipitated in hexane. After filtered
and dried in a vacuum oven, a brown solid (0.71 g, 56%) was obtained.
1H NMR (600 MHz, CDCl3), δ (ppm): 7.24 (s, 1H, H at the triazole
ring), 6.92 (s, 1H, phenyl H-4), 6.85 (s, 2H, phenyl H-2), 4.80 (s, 1H,
H at the bridging C), 4.67 (s, 4H, CH2OH), 4.46 (t, 2H, COOCH2),
4.33 (t, 2H, CH2O−Ar), 3.97 (t, 2H, CH2 linked to N in the triazole
ring), 2.69 (t, 2H, CH2 linked to C in the triazole ring), 1.92 (m, 2H,
COOCH2CH2), 1.86 (m, 2H, CH2CH2O−Ar), 1.77 (m, 2H, CH2CH2
linked to N in the triazole ring), 1.66 (m, 2H, CH2CH2 linked to C in
the triazole ring), 1.52−1.38 (m, 14H, COOCH2CH2CH2CH2-
CH2CH2CH2 and CH2CH2CH2CH2O−Ar). 13C NMR (600 MHz,
CDCl3), δ (ppm): 166.48 (CO), 159.53 (phenyl carbon adjacent to
oxygen), 148.31, 145.86, 145.59, 145.26, 145.22, 145.18, 145.09,
145.08, 144.73, 144.69, 144.67, 144.60, 144.58, 144.41, 143.95, 143.73,
143.26, 143.09, 143.02, 142.98, 142.86, 142.82, 142.43, 142.20, 142.09,
141.13, 140.92, 140.47, 136.38, 120.50, 117.46, 112.22, 70.64 (sp3
carbons of fullerene), 67.67, 66.63, 65,16, 50.10 (CH2N), 39.18
(bridging methene carbon to fullerene), 30.13, 29.45, 29.42, 29.28,
29.25, 28.77, 28.70, 26.07, 26.02, 25.59, 25.48. The 28 resonances from
140.47 to 149.31 ppm belong to the carbons from fullerene plus one
for the carbons in the phenyl group linked with hydroxymethylene
group. The resonances at 136.38 and 120.50 ppm are from triazole
carbons, while at 117.46 and 112.22 ppm are from the methene
carbons of benzene. The resonances at 67.67, 66.63, and 65.16 ppm
are from methylene carbons connected with oxygen, while the other
11 resonances from 30.13 to 25.48 ppm belong to the 11 methylene
carbons with adjacent methylene groups.
GPC was conducted on a Waters GPC systems equipped with a
Waters 1515 isocratic HPLC pump, a Waters 2489 UV−vis detector,
and a set of Waters Styragel columns (HR3, HR4, and HR5 with
molecular weight range of 5 × 102−4 × 106 Da). The monomer and
polymer solutions were freshly prepared by dissolving in chloroform
(0.5 mg/mL) and then filtering through 0.45 μm PTFE syringe-type
filters before being injected into the GPC system. Chloroform was
served as the mobile phase at a flow rate of 1.0 mL/min at 35 °C. TGA
was carried on a SDT-2960TG/DTA TA Instruments at a heating rate
of 10 °C min−1 from room temperature to 800 °C under a continuous
nitrogen flow of 50 mL/min. The differential scanning calorimetry
(DSC) was performed on a TA Instruments DSC 2010 over a
temperature range of 0−280 °C at a scanning rate of 10 °C/min. UV−
vis spectra were recorded on a Hitachi U-3900 spectrophotometer at
room temperature. For Fourier transform infrared spectroscopy
(FTIR) measurements, samples were dispersed in potassium bromide
and compressed into pellets, and spectra in the range of 400−4000
cm−1 were recorded with the Nicolet 6700 FT-IR Instrument. Atomic
force microscopy (AFM) image was carried out on a MultiMode 8
atomic force microscope (Bruker Veeco) in Peak Force QNM mode in
air, and a SNL-10 cantilever (spring constant: 0.35 N/m; resonance
frequency: 50−80 kHz) was used for measurement.
Synthesis of Dicarbonyl Chlorides. 2,5-Thiophenedicarbonyl
chloride, 1,4-naphthalenedicarbonyl chloride, and 2,5-dibromo-
terephthaloyl chloride were synthesized from their corresponding
diacids. A typical procedure is described in the following: excess of
thionyl chloride (20 mL) was added to a flask containing
corresponding diacid (1.5 g), and then a drop of DMF was added.
The reaction mixture was refluxed for 6 h. The excess thionyl chloride
was removed by rotation evaporation under reduced pressure. The
For refractive index measurements, a spectroscopic ellipsometer
(M2000, J.A. Woollam Co.) was used to measure the ellipsometric
data Psi (Ψ) and Delta (Δ) of the polymer films. All measurements
C
Macromolecules XXXX, XXX, XXX−XXX