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Chem. Mater., Vol. 22, No. 11, 2010 3325
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Haen), zinc chloride (pure, Merck), basic Al2O3 (for chromato-
added at 0 °C dropwise 2-(4-vinyl-benzylsulfanyl)-ethanol
(24.42 g, 0.126 mol) in methanol (400 mL). The mixture is stirred
for 2 days at ambient temperature, filtered, and extracted 4 times
with 400 mL of CHCl3. The combined organic phases were dried
over MgSO4 and evaporated. The residue was crystallized from
n-hexane after adding of a small amount of 2,6-ditert-butyl-4-
methylphenol to give colorless crystals (mp 83 °C). Yield 15.82 g
(80 mmol, 64%).
graphie, Acros), and NaOH solution (1 M, Merck) were used as
received. DMSO (dimethylsulfoxide), THF (tetrahydrofurane),
n-hexane, methanol, and N,N-dimethylformamide (DMF) were
analytical grade. Initiators V-50 (2,20-Azobis(2-methylpropio-
namidine)dihydrochloride) and VA-044 (2,20-Azobis[2-(2-imidazo-
lin-2-yl) propane]dihydrochloride) were a kind gift of Wako Che-
micals GmbH. Branched polyethyleneimine (PEI, Mw ≈ 25 000 g/
mol) was from Sigma-Aldrich. Milli-Q water (18.2 MΩ cm) was
used in all experiments. All aqueous polymer solutions were used
after filtration. Dialysis tubes “ZelluTrans” (Roth, Germany) had a
nominal molar mass cut off of 3500 D. The synthesis of sodium
2-benzylsulfanylthiocarbonylsulfanyl-ethanesulfonate,41 (UV-vis
in water: band at λ max= 425 nm, extinction coefficient ε = 49.3
L mol-1 cm-1), and polycation poly(4-methyl-1-(4-vinylbenzyl)-
pyridinium chloride, PC,40 were reported before.
Elemental analysis: (C11H14O2S, Mr = 210.29): Calcd: C,
62.83; H, 6.71; S, 15.25. Found: C, 62.72; H, 6.67; S, 15.25.
1H NMR (200 MHz, in methanol-d4, δ in ppm) 7.48 (d, 2H,
CH aryl); 7.36 (d, 2H, CH aryl); 6.77 (dd, 1H, aryl-CHd); 5.83
(dd, 1H, aryl-CdCH (Z)); 5.28 (dd, 1H, Aryl-CdCH (E));
4.06, 3.96 (d þ d, 2H þ 2H, aryl-CH2-S(dO)-); 3.99-3.96 (m,
2H, -CH2-OH); 3.02, 2.84 (m þ m, 2H þ 2H, S(dO)-CH2-).
13C NMR (75 MHz, in MeOH-d4, δ in ppm) 139.0, 137.3,
131.8, 131.1, 127.5, 114.7 (-Cdaryl þ alkene); 58.4 (-CH2-O);
55.7 (aryl-CH2-S(dO)-); 54.9 (S(dO)-CH2-).
Synthesis of Sodium 3-(4-Vinyl-benzylsulfanyl)-propane-1-sul-
fonate. Sodium 3-mercaptopropanesulfonate (12.11 g, 67 mmol)
in THF (30 mL) and 82 mL of 1 M NaOH were refluxed for
30 min. 4-Vinylbenzylchloride (10.38 g, 68 mmol) and a small
amount of 2,6-ditert-butyl-4-methylphenol in THF (56 mL)
were then added dropwise within 25 min. The mixture was refluxed
for 4 h and stirred at ambient temperature overnight, and then
diluted with water (200 mL) and precipitated into acetone. The
resulting suspension was filtrated and the filtrate concentrated
under reduced pressure. The resulting precipitate was filtered off
and dried in vacuo at 40 °C. Yield: 9.4 g (32 mmol, 48%) of sodium
3-(4-vinyl-benzylsulfanyl)-propane-1-sulfonate, a colorless powder
that decomposes at 132 °C.
MS (ESI): m/z (%) = 210 [Mþ]; 117 [Mþ - S(dO)-CH2-
CH2OH].
Synthesis of the Polyanions. In a typical polymerization
procedure, sodium 3-(4-vinyl-benzylsulfanyl)-propane-1-sulfo-
nate (3.599 g, 12.2 mol), 2-(4-vinyl-phenylmethanesulfinyl)-
ethanol (0.2848 g, 1.2 mmol) and RAFT agent sodium 2-ben-
zylsulfanyl-thiocarbonylsulfanylethanesulfonate (0.0446 g, 0.1368
mmol) were dissolved in 50 mL aqueous methanol (52 vol%).
Then, 2 mL of a solution containing initiator V-50 (0.00454 g,
0.0167 mmol in water, 10 mL) was added. The mixture was
purged with nitrogen for 15 min and then heated to 60 °C for
150 min. The polymer was isolated and purified by dialysis and
lyophilized, to yield 1.16 g of polymer (colorless hygroscopic
powder).
Elemental analysis: (C12H15O3S2Na, Mr = 294.37): Calcd: C,
48.96; H, 5.14; S, 21.78. Found: C, 48.84; H, 5.08; S, 21.62.
1H NMR (200 MHz, in D2O, δ in ppm) 7.36 (d, 2H, CH aryl);
7.23 (d, 2H, -CH aryl); 6.68 (dd, 1H, aryl-CHd); 5.77 (dd, 1H,
aryl-CdCH (Z)); 5.22 (dd, 1H, aryl-CdCH (E)); 3.65 (s, 2H,
aryl-CH2-S), 2.85 (t, 2H, -CH2-SO3); 2.46 (t, 2H, S-CH2-C)
1.90 (m, 2H, -CH2-).
Multilayer Film Preparation by Spraying. The LbL films were
assembled on silicon wafers (CrysTec) and on quartz slides
(QSIL AG, Germany) from 1 mg/mL polymer solutions by
the spray coating method.42,43 The substrates were cleaned using
RCA method (sonication in a 1:1 mixture of water and 2-pro-
panol for 15 min),44 followed by heating at 70 °C in a 5:1:1
mixture of water, 25% ammonia solution, and 30% hydrogen
peroxide solution for 10 min. The freshly cleaned substrate was
than precoated with one layer of PEI, which was allowed to
adsorb onto the negatively charged surface during 20 min before
rinsing with water.
13C NMR (75 MHz, in D2O, δ in ppm) 138.6, 136.7, 129.7,
126.7, 114.6 (-Cdaryl þ alkene); 50.2 (CH2-SO3); 35.0 (aryl-
CH2-S); 29.7 (-S-CH2-); 24.3 (-CH2-).
MS (ESI) m/z (%) =271.04 (100) (Mþ-Na); m/z 148.9 (7.2)
(Mþ-S-CH2CH2CH2-SO3Na).
Synthesis of 2-(4-Vinyl-benzylsulfanyl)-ethanol. 4-Vinylben-
zylchloride (38.87 g, 0.257 mol) was added during 60 min to a
solution of 2-mercaptoethanol (21.17 g, 0.257 mol) and a small
amount of 2,6-ditert-butyl-4-methylphenol in 250 mL of 1 M
aqueous NaOH and 150 mL of THF, while refluxing. The mixture
was refluxed overnight, diluted with 500 mL of water, and extracted
four times with 500 mL of CH2Cl2. The organic phases were
combined, dried over MgSO4, and evaporated to give the product
as colorless, waxy solid (mp 39 °C).Yield:48.85g(0.251mol,98%).
1H NMR (200 MHz, in methanol-d4, δ in ppm) 7.40,7.36
(dþd, 2Hþ2H, CH aryl); 6.71 (dd, 1H, aryl-CHd); 5.78 (dd,
1H, aryl-CdCH (Z)); 5.22 (dd, 1H, aryl-CdCH (E)); 3.74
(s, 2H, aryl-CH2-S); 3.32 (t, 2H, -CH2-O); 2.55 (t, 2H,
S-CH2-).
The PEI-coated substrate was vertically placed in a home-
made spray unit. The polyelectrolyte solutions containing pre-
cise concentrations of NaCl (0.02 M, 0.05 M, or 0.20 M) were
filled into spray bottles (10 mL, NeoLab Migge GmbH,
Germany) which were manually pressurized twice for each
deposition step. After each step, the polymer was allowed to
adsorb for 10 s before water was sprayed for 10 s (200 mL spray
bottles “air boy”, Carl Roth GmbH, Germany) to rinse the
surface. The films were dried in a stream of nitrogen before
characterization.
Cross-Linking. Cross-linking was performed on films depos-
ited on quartz slides. The film coated substrate was immersed at
room temperature into the solution of terephthalaldehyde
(20 mg) in methanol (5 mL) adding piperidine (2 drops) as
catalyst,45 followed by rinsing with methanol and water and
13C NMR (75 MHz, in CDCl3, δ in ppm) 137.9, 136.7, 136.6,
129.4, 126.7, 114.3 (-Cdaryl þ alkene), 61.2 (-CH2-OH)),
35.7 (aryl-CH2-S-); 33.4 (S-CH2-).
MS (ESI): m/z (%) = 195 [Mþ]; 117 [Mþ - SCH2CH2OH].
Synthesis of 2-(4-Vinyl-phenylmethanesulfinyl)-ethanol. So-
dium periodate (30.87 g, 0.144 mol) in water (300 mL) was
(42) Schlenoff, J. B.; Dubas, S. T.; Farhat, T. Langmuir 2000, 16(26),
9968–9969.
(43) Izquierdo, A.; Ono, S. S.; Voegel, J. C.; Schaaff, P.; Decher, G.
Langmuir 2005, 21(16), 7558–7567.
(44) Kern, W.; Puotinen, D. A. RCA Rev. 1970, 31(2), 187–206.
(45) Phillips, A. P. J. Org. Chem. 1949, 14(2), 302–305.
(41) Baussard, J. F.; Habib-Jiwan, J. L.; Laschewsky, A.; Mertoglu, M.;
Storsberg, J. Polymer 2004, 45(11), 3615–3626.