2964 Gomurashvili and Crivello
Macromolecules, Vol. 35, No. 8, 2002
was filtered, and the solvent and excess vinyl ether were
evaporated under reduced pressure. Toluene was added to the
residue, and the precipitated unreacted 10H-phenothiazine
was removed by filtration. Evaporation of the toluene and
distillation of the resulting oil at 170-175 °C (0.01T) afforded
5.4 g of VPT as a pale yellow oil. (lit.20 bp0.1Torr 150-170 °C).
1H NMR (500 MHz, CDCl3): δ (ppm) 7.29-6.92 (m; aromatic
protons), 6.48 (q, -CHdCH2), 4.26-4.20 (m, N-CH2-CH2-
N), 4.08 (m; CHdCH2).
sion wavelength maximum at 250 nm. After 10 min of
irradiation, the sample tubes were withdrawn and the contents
poured into 50 mL of cold methanol, containing ca. 5 mL of
pyridine. The precipitated polymers were isolated by filtration,
washed with cold methanol, and dried overnight in a vacuum
oven at 45 °C.
Meth od B. Low-temperature cationic polymerizations were
carried out at the designated temperatures by injecting boron
triflouride etherate through a rubber septum into a flask that
had been charged with a solution of 2.0 g of the monomer and
25 mL of dry dichloromethane. After 45 min of stirring, the
reaction was quenched by the addition of 3 mL of cold pyridine
and then poured into cold ether. The precipitated polymer was
collected by filtration, washed with ether, and dried overnight
in a vacuum oven at 45 °C.
Dir ect Oxid iza tion of P olym er P VP T. Polymer PVPT
(0.5 g) was dissolved in 45 mL of dichloromethane and treated
with 6 mL of glacial acetic acid and 2 mL of 30% hydrogen
peroxide. The mixture was brought to reflux, and after 2 h,
an additional 1 mL of hydrogen peroxide was added and
refluxing continued overnight. The oxidized polymer was
precipitated into cold methanol, filtered, and dried at 45 °C
in a vacuum oven. The polymer, CoPVT, was characterized
by FT-IR. The polymer was soluble in dichloromethane and
4-vinylcyclohexene diepoxide but was insoluble in cyclohexene
oxide.
P h otop olym er iza tion Stu d ies. The cationic photopoly-
merizations of all the monomers were monitored using Fourier
transform real-time infrared spectroscopy (FT-RTIR). A Midac
M-1300 FTIR spectrometer (Midac Corp., Irvine, CA) equipped
with a liquid nitrogen cooled mercury-cadmium-telluride
detector was used. The instrument was fitted with a UVEXS
model SCU-110 mercury arc lamp (Sunnyvale, CA) equipped
with a flexible liquid optic wand. The end of this wand was
placed at a distance of 4-20 cm and directed at an incident
angle of 45° onto the sample window. UV light intensities were
measured with the aid of a UV Process Supply, Inc. radiometer
(Chicago, IL) at the sample window.
Anal. Calcd for C16H15NOS: C, 71.34; H, 5.61; N, 5.20; S,
11.90. Found: C. 71.69; H, 5.64; N, 5.23; S, 11.88.
P r ep a r a tion of 10-P h en oth ia zin e-5-oxid e (P TO). PTO
was synthesized using the procedure described by Gilman and
Nelson.21 Recrystallization of the crude product from 96%
ethanol produced 17 g (93%) of yellow crystals of PTO having
a mp 269-272 °C (lit.21 mp 242-242.5 °C dec). The IR
spectrum of the product displayed characteristic sulfoxide
bands at 1074 and 1029 cm-1
.
Anal. Calcd for C12H9NOS: C, 66.95; H, 4.21; N, 6.51; S,
14.90. Found: C. 67.00; H, 4.26; N, 6.48; S, 14.85.
P r ep a r a tion of 10H-P h en oth ia zin e-5,5-d ioxid e (P TO2).
The synthetic procedure of Gilman and Eisch was employed
for the preparation of PTO2.22 After recrystallization from
ethanol, an 88% yield of colorless crystalline 10-phenothiazine-
5,5-oxide was obtained with a mp range of 264-266 °C. (lit.22
mp 253.5-255.5 °C). The IR spectrum of the product displayed
characteristic sulfone bands at 1153 and 1125 cm-1
.
P r ep a r a tion of 10-(2-Vin yloxyeth yl)p h en oth ia zin e-5-
oxid e (VP TO) a n d 10-(2-Vin yloxyet h yl)p h en ot h ia zin e-
5,5-d ioxid e (VP TO2). The preparation of VPTO and VPTO2
were carried out analogous manner to the synthesis of VPT
replacing 10H-phenothiazine with 10H-phenothiazine-5-oxide
and 10H-phenothiazine-5,5-dioxide as starting materials. After
recrystallization twice from toluene, a 46% yield of off-white
colored crystals of VPTO with a mp of 109-111 °C were
collected.
1H NMR (500 MHz, DMSO-d6): δ (ppm) 7.96-6.27 (m;
aromatic protons), 6.54-6.24 (q, -O-CHd), 4.65-4.14 (t,t,
N-CH2-CH2, 4.25 and 3.99 (q,q; -CHdCH2)).
Anal. Calcd for C16H15NO2S: C, 67.35; H, 5.30; N, 4.91; S,
11.24. Found: C, 67.42; H, 5.25; N, 4.96; S, 11.41.
Monomer VPTO2 was obtained after recrystallization from
ethanol as a white crystalline powder mp 115-117 °C in a
yield of 42%. The IR spectrum of the product VPTO2 displayed
characteristic sulfone bands at 1165 and 1141 cm-1 (KBr).
1H NMR (500 MHz, DMSO-d6): δ ) 8.00-7.32 (m; Ar), 6.47
(q; -CHdCH2), 4.64 and 4.07 (t,t; - CH2-CH2-N<), 4.21 and
3.98 (q,q; -CHdCH2).
Anal. Calcd for C16H15NO3S: C, 63.77; H, 5.02; N, 4.65; S,
11.24. Found: C, 64.03; H, 5.17; N, 4.61; S, 11.46.
P olym er iza tion of P h en oth ia zin e Mon om er s EP T, c-
a n d t-P P T, VP T, a n d VP TO2. The experimental conditions
and results obtained in the cationic polymerizations of the
phenothiazine monomers are summarized in Table 1.
Photopolymerizations were carried out at room temperature
in solutions of the monomers containing various concentrations
-
of IOC10, SOC10, or DPS-C1C12PF6 as the photoinitiator.
All photoinitiator concentrations in this paper are given in
units of mol % with respect to the epoxide or vinyl ether
monomer. The monomer/photoinitiator solutions were coated
onto a 12 µm oriented and corona-treated polypropylene films
(General Electric Capacitor Department, Hudson Falls, NY),
covered with an identical polypropylene film, and then mounted
in 5 cm × 5 cm slide frames. The thickness of the liquid
monomer films was estimated at 10-25 µm. Infrared spectra
were collected at a rate of 1 spectrum per second using
LabCalc, data acquisition software obtained from the Galactic
Industries Corp. (Salem, NH) and were processed using
GRAMS-386 software from the same company. During irradia-
tion, the decrease of the IR absorbance due to either the vinyl
ether double bonds centered at 1610 cm-1, the 1-propenyl
groups at 1661-1669 cm-1or the epoxy groups between 790
and 915 cm-1 of the monomers were monitored. In all cases,
three to five runs were recorded and the results averaged. Data
reduction and subsequent conversion vs time plots were
obtained using Excel (Microsoft Corp., Redmond, WA) soft-
ware.
Ta ble 1. Ca tion ic P olym er iza tion of P h en oth ia zin e (P zn )
Mon om er s in CH2Cl2
monomer
concn
reacn reacn
Pzn
initiator time temp yield
monomer
EPT
c- and t-PPT
VPT
(mol‚L-1
) meth (1.0 wt %) (min) (°C) (%) Mn
a
0.9
2.5
0.5
0.5
B
A
B
B
BF3Et2O
IOC10
60
10
45
45
-10
25
-45
-30
55
85
b
900
BF3Et2O
BF3Et2O
78 1600
75
Resu lts a n d Discu ssion
VPTO2
c
Although phenothiazines are an efficient and conve-
nient class of photosensitizers for onium salt photoini-
tiated cationic polymerizations,9 they suffer from the
drawback that many of these compounds display physi-
ological effects in man. For this reason, it is important
that in any application in which they are used, contact
with these compounds be minimized. It is also necessary
to make certain that residues containing the photosen-
sitizers are not exuded or extracted from the polymers
that are produced on photopolymerization. This is an
a
From GPC measurements (in THF, polystyrene standards.).
b
c
ηinh ) 0.018 dL/g measured in CH2Cl2 at 20 °C, c ) 0.5 g/L. ηinh
) 0.02 dL/g measured in DMAc at 25 °C, c ) 0.5 g/L.
Meth od A. Photoinduced cationic polymerizations were
carried out by dissolving 3.0 g of monomer and 1.0% of IOC10
in 5 mL of dry dichloromethane and placing the solutions in
sealed 15 mm i.d. quartz reaction tubes. The samples were
irradiated at 25 °C in
equipped with 16 low-pressure mercury lamps with an emis-
a Rayonet photochemical reactor