Supporting Information
A Study on Emulsion Stabilization Induced with Linear and Cyclized
Polystyrene-Poly(ethylene oxide) Block Copolymer Surfactants
Eisuke Baba, Toshiaki Yatsunami, Takuya Yamamoto and Yasuyuki Tezuka*
Department of Organic and Polymeric Materials, Tokyo Institute of Technology, O-okayama,
Meguro-ku, Tokyo 152-8552, Japan
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EXPERIMENTAL PROCEDURES
Reagents
Poly(ethylene oxide), PEO, macroinitiator having 2-bromoisobutyryl terminal
groups (Mn(NMR) = 2300) was prepared by the esterification of poly(ethylene oxide) (Mn
= 2000, Aldrich) with α-bromoisobutyryl bromide (98%, Aldrich) in the presence of
triethylamine (99%, Kanto Chemical Co., Inc.) as reported previously.1,2
Styrene
(99%, Nacalai Tesque, Inc.) was purified through alumina column to remove
polymerization inhibiter. The reagents for the preparation of a block copolymer, i.e.,
CuBr (99%, Nacalai Tesque, Inc.), N,N,N',N'',N''-Pentamethyldiethylenetriamine
(PMDETA) (98%, TCI), allyltrimethylsilane (98%, Aldrich) and TiCl4 (99%, Nacalai
Tesque, Inc.) were used as received.
The solvent for the allylation reaction (CH2Cl2,
99%, Kanto Chemical Co., Inc.) was distilled over CaH2 before use.
The reagents for
the cyclization reaction, i.e. Hoveyda-Grubbs catalyst 2nd generation (Aldrich), ethyl
vinyl ether (99%, Aldrich), toluene (99%, Kanto Chemical Co., Inc.) and activated
alumina (300 mesh, Wako Pore Chemical Industries, Ltd.) were used as received.
For
the emulsion stabilization experiments, toluene (99%, Kanto Chemical Co., Inc.) was
used as received, while water was distilled before use.
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Synthesis of a linear PS-PEO-PS block copolymer having allyl end groups (1)3,4,5
A weighed amount of the PEO macroinitiator (979 mg, 0.404 mmol), styrene (9.5
mL, 83 mmol), CuBr (170 mg, 1.2 mmol) and PMDETA (0.26 mL, 0.12 mmol) were
placed in a 30 mL flask.
After the flask was degassed by freeze-pump-thaw cycles, the
polymerization reaction of styrene was allowed to proceed under stirring for 3.5 h at
90 °C.
The solidified mixture was then dissolved in CHCl3 and poured into methanol
to recover the precipitated product, which was again dissolved in CHCl3 for the
treatment of a plug of alumina to remove the catalyst residue.
The eluted product
solution was concentrated and poured into methanol to obtain the PS-PEO-PS block
copolymer product having bromoalkyl end groups as a white solid precipitate (3.72 g,
82% yield).
Thereafter, a part of the product (990 mg, 89 mol) was dissolved in
CH2Cl2 (0.8 mL), and allyltrimethylsilane (1.25 mL, 11.4 mmol) and TiCl4 (1.25 mL,
7.87 mmol) were added.
After the reaction under stirring for 30 min at room
temperature, methanol was added to quench the reaction. The crude product was
recovered after the concentration and the subsequent precipitation into methanol as a
white solid (787 mg, 77% yield).
The product having allyl end groups (1) was finally
isolated by means of the preparative SEC fractionation (CHCl3 as an eluent at a flow
rate of 3.5 ml min–1) in the yield of 463 mg.
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1
H NMR (Figure S1, top): δ (ppm)
0.79-1.08 (m, CH3) 1.08-2.58 (m, -CH2CH(Ph)-, -CH2CH(Ph)-), 3.29-3.95 (m, -OCH2-)
4.72-4.96
(m,
-CH2CH=CH2),
5.36-5.61
(m,
-CH2CH=CH2),
6.30-7.38
(m,
-CH2CH(C6H5)-). Mn (NMR) = 4100-2100-4100, SEC (Figure S2, top): Mp (peak MW)
= 15000, PDI = 1.13.
Synthesis of a cyclized PS-PEO block copolymer (2)3
Into a 1 L toluene solution containing a weighed amount of 1 (200 mg, 18.8
µmol), Hoveyda-Grubbs 2nd generation catalyst (60 mg, 95 µmol) was added to
proceed the reaction under stirring for 21 h at 70 °C.
Ethyl vinyl ether (10 mL) was
then added to the mixture to deactivate the catalyst under stirring for 30 min at 70 °C.
The cyclized PS-PEO block copolymer product (2) was isolated after the precipitation
into methanol as a pale brown solid (123 mg, 59% yield).
1
H NMR (Figure S1,
bottom): δ (ppm) 0.80-1.09 (m, CH3) 1.09-2.56 (m, -CH2CH(Ph)-, -CH2CH(Ph)-),
3.29-3.99 (m, -OCH2-) 4.69-4.95 (m, -CH=CH), 6.29-7.42 (m, -CH2CH(C6H5)-).
Mn(NMR) = 8900-2100, SEC (Figure S2, bottom): Mp (peak MW) = 12000, PDI = 1.10.
Measurements
1
H NMR spectra were recorded on a JEOL JNM-AL300 spectrometer operating at
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300 MHz using CDCl3 as a solvent. Proton chemical shifts were reported relative to the
signal of tetramethylsilane. SEC measurements were performed on a Tosoh model
CCPS equipped with a refractive index detector model RI 8020 and a TSK G3000HXL
column equilibrated at 40 °C.
THF was used as an eluent at a flow rate of 1.0 mL/min.
A set of linear PS standards were used for calibration, and the peak molecular weight
(Mp) of polymer samples were reported as a linear PS equivalent.
References
1.
Adachi, K.; Honda, S.; Hayashi, S.; Tezuka, Y. Macromolecules 2008, 41,
7898–7903.
2. Hayashi, S.; Adachi, K.; Tezuka, Y.
3.
Chem. Lett. 2007, 36, 982–983.
Baba, E.; Honda, S.; Yamamoto, T.; Tezuka, Y.
Polym. Chem. 2012, 3,
1903–1909.
4.
Fonagy, T.; Schulze, U.; Komber, H.; Voigt, D.; Pionteck, J.; Ivan, B.;
Macromolecules 2007, 40, 1401–1407.
5.
Schulze, U.; Fonagy, T.; Komber, H.; Pompe, G.; Pionteck, J.; Ivan, B.;
Macromolecules, 2003, 36, 4719–4726.
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Figure S1: 300 MHz 1H NMR spectra of (top) a linear PS-PEO-PS block copolymer
having allyl end groups (1) and (bottom) a cyclized PS-PEO block copolymer (2)
(CDCl3, r.t.)
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Figure S2: SEC traces of (top) a linear PS-PEO-PS block copolymer having allyl end
groups (1) and (bottom) a cyclized PS-PEO block copolymer (2) (THF as an eluent, 1.0
mL/min)
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Figure S3: Time dependence (up to 30 min) of the volume ratio of the separated water
layer from the water phase emulsion in the presence of (left) a linear PS-PEO-PS block
copolymer (1) and (right) a cyclized PS-PEO block copolymer (2) (the initial surfactant
concentration of 0.2 g/L in toluene) at toluene/water ratio of 10/15 (mL/mL), and at 50
o
C. The emulsion was formed by shaking the sample solution in a glass cylinder either
by 10, 100 or 200 times in about 1 min.
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Figure S4: Time dependence of the volume ratio of the separated water layer from the
water phase emulsion in the presence of (left) a linear PS-PEO-PS block copolymer (1)
and (right) a cyclized PS-PEO block copolymer (2) (the initial surfactant concentration
of 0.1 g/L in toluene) at toluene/water ratio of 10/10 (mL/mL), and at 50 oC. A set of
five experiments (○,△,□ and ●) were conducted by using separately prepared samples
and the average of the medium three (○,△,□) was used to represent the results in
Figures 2 and 3.
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Figure S5: Time dependence of the volume ratio of the separated toluene layer from the
toluene phase emulsion in the presence of (●,▲,■) a linear PS-PEO-PS block
copolymer (1) and (○,△,□) a cyclized PS-PEO block copolymer (2) (the initial
surfactant concentration of 0.1 g/L in toluene) at toluene/water ratio of 10/10 (mL/mL),
and at 25 (● and ○), 50 (▲ and △) and 75 oC (■ and □).
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