Macromolecules
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Preparation of 2,3-Di(n-hexylphenyl)-1,3-butadiene (3). The
preparation of monomer 3 was similar to the preparation of 1 except
that n-hexylbezene was used in the reaction of acetylation. Yield:
of methanol to precipitate the polymer. After dried under vacuum for
24 h, β-SPA(1)25 was obtained as a brown powder. Yield: 0.29 g
(90.6%). Mn, GPC = 3.2 × 103 g/mol, PDI = 1.65 (high temperature
GPC in 1,2,4-trichlorobenzene).
1
57.7%. H NMR (500 MHz, CDCl3), δ (TMS, ppm): 0.90 (t, 6H,
Measurements. 1H and 13C NMR measurements were carried out
CH2−CH3), 1.30 (m, 12H, −CH2−(CH2)3−CH3), 1.60 (m, 4H,
−Ar−CH2−CH2−), 2.55 (t, 4H, −Ar−CH2−), 5.25,5.55 (d, 4H,
−CCH2), 7.08,7.34 (d, 8H, −ArH−). 13C NMR (400 MHz,
CDCl3), δ (ppm): 149.8, 142.4, 137.6, 128.3, 127.3, 115.4, 35.7, 31.8,
31.4, 29.1, 22.7, 14.2. FTIR: 2956, 2926, 2855, 1610, 1510, 1465, 898,
854. MS: m/z calcd for C28H38 (M + H)+, 375; found, 375.
on a Bruker 500 and 400 MHz NMR instrument respectively, using
̈
CDCl3 as the solvent and tetramethylsilane as the interior reference.
Gel permeation chromatography (GPC) analysis was performed
through three TSK gel columns (pore size 15, 30, and 200 Å),
calibrated by narrow polystyrene standards, and equipped with three
detectors: a DAWN HELEOS (14−154°) (Wyatt multiangle laser
light scattering detector, He−Ne 658.0 nm), ViscoStar (Wyatt), and
Optilab rEX (Wyatt). THF was used as the eluent at a flow rate of 1.0
mL/min at 35 °C. Mw was obtained by DAWN HELEOS in the online
mode, with dn/dc values determined in Optilab rEX. UV spectra were
recorded on a PerkinElmer Lambda 750 UV−visible spectrometer
with a 1 cm2 quartz cell. THF was used as the solvent. Element
analysis of brominated polymers were carried out by oxygen flask
combustion method or by XPS (for α-SPAs) using PHI 5000C ESCA
System. High temperature GPC were carried out on Agilent PL-GPC
220, using 1,2,4-trichlorobenzene as the eluent at a flow rate of 1.0
mL/min at 150 °C. Variant temperature NMR were performed on an
Agilent Direct-Drive II 600 M Hz spectrometer equipped with four
broad-band rf channels and a 5 mm 1H−19F/15N−31P pulse field
gradient (PFG) probe. The spectra in C2D2Cl4 was collected with a 1 s
acquisition time, 3 s relaxation delay, 9.6 kHz spectral window, 256
transients, and 9.2 μs 90° pulse width. The data were exponentially
weighted with a line broadening of 0.5 Hz.
Polymerization of 1. All of anionic polymerizations were
performed in Schlenk apparatus connected to vacuum/argon lines.
The flask with a magnetic stir bar inside was dried by three cycles of
flaming/Ar purging/evacuating and rinsed with a dilute solution of n-
BuLi in cyclohexane, then pure cyclohexane, for several times.
Monomer 1 was dried under high-vacuum condition for 24 h prior
to polymerization. A volume of 50 mL of cyclohexane was distilled
into the flask, and the impurities was titrated with DPELi (adduct of s-
BuLi and 1,1-diphenylethylene) until red color appeared. Then THF
(0.11 mL, 1.30 mmol) and 1 (1.00 g, 3.20 mmol) were added to form
a solution. s-BuLi in cyclohexane/hexane (0.10 mL, 0.13 mmol) was
added at 10 °C for 30 min, then the temperature was raised to 40 °C
for 2 h. The polymerization was terminated with degassed methanol
and the resulting polymer was precipitated from methanol and dried
under vacuum for 24 h. Poly(1)25 was obtained as white powder.
Yield: 0.98 g (98.0%). Mn,GPC = 4.9 × 103 g/mol, PDI = 1.05, Mw,MALLS
= 7.9 × 103 g/mol.
The preparation of poly(1)50, poly(1)300, poly(2)30, and poly(3)25
were similar to the polymerization of poly(1)25 except that the
different monomers or amount were used. These results were
presented in Supporting Information Table S3 and Figures S3−S12.
Block Copolymerization. Styrene was distilled over di-n-
butylmagnesium (MgBu2) on the vacuum line prior to polymerization.
The synthesis of poly(1)-b-polystyrene was conducted by sequential
addition of two monomers in 40 °C. A volume of 50 mL of
cyclohexane was distilled into the flask, and titrated with DPELi until a
red color appeared. Then THF 0.11 mL (1.30 mmol) and monomer 1
(1.45 g, 4.55 mmol) were added to form a solution. s-BuLi in
cyclohexane/hexane (0.10 mL, 0.13 mmol) was added at 10 °C for 30
min, then the temperature was raised to 40 °C for 2 h. Styrene (0.41 g,
3.9 mmol) was added at 10 °C, then the temperature was raised to 40
°C for 4 h. The polymerization was terminated with degassed
methanol, and the product was precipitated in methanol and dried
under vacuum for 24 h. Poly(1)25-b-polystyrene was obtained as white
powder. Yield: 1.80 g (96.8%). Mn, GPC = 13.8 × 103 g/mol, PDI =
1.14.
General Procedure for Bromination−Dehydrobromination.
A solution of bromine in dichloromethane (4.0 mmol, 3 mL) was
added dropwise to a solution of poly(1)25 solution in dichloromethane
(0.64 g, 5 mL) at 0 °C. The mixture was stirred for 4 h and the
product was precipitated into methanol and dried under vacuum for 24
h. Poly(1)25-Br was obtained as a greenish brown colored powder.
Yield: 0.89 g (93.0%). Mn, GPC = 5.9 × 103 g/mol, PDI = 1.14.
The elimination of HBr was performed in THF solution at room
temperature. A solution of potassium tert-butoxide in anhydrous THF
(5.0 mmol, 5 mL) was added dropwise to a solution of Poly(1)25-Br in
THF (0.30 g, 10 mL) under nitrogen. The mixture was stirred for 12 h
and then dialyzed in deionized water and acetone, respectively, for 2
days and 4 h. The slurry in the bag was dissolved in THF and dried
with anhydrous sodium sulfate. After evaporation of the solvent, α-
SPA(1)25 was obtained as a dark brown powder. Yield: 0.16 g, 80.0%.
Mn, GPC = 2.4 × 103 g/mol, PDI = 2.26 (high temperature GPC in
1,2,4-trichlorobenzene).
ASSOCIATED CONTENT
* Supporting Information
Sythesis details, results of conventional and high temperature
GPC, 1H NMR, and elemental analysis of concerned
conjugated (co)polymers. This material is available free of
■
S
AUTHOR INFORMATION
Corresponding Author
*(J.H.) Telephone: +86-21-6564-3509. E-mail: jphe@fudan.
■
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
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We express thanks for the continuing financial support by the
National Nature Science Foundation of China (21074024 &
21474016).
REFERENCES
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General Procedure for the Dehydrogenation of Precursor
Polymers with DDQ. A powder of poly(1)25 (0.32g, containing 1.00
mmol of butadiene units) was dried under vacuum in a 50 mL Schlenk
tube. Toluene (3 mL) was added using a syringe, and the mixture was
stirred until the polymer was completely dissolved. A solution of DDQ
in toluene (0.91 g, 4.0 mmol, 3 mL) was added using a syringe. The
mixture was stirred at 90 °C for 24 h, then poured into a large volume
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dx.doi.org/10.1021/ma501283b | Macromolecules XXXX, XXX, XXX−XXX