Macromolecules, Vol. 36, No. 14, 2003
2,2,4,4,6,6-Hexamethyl-8,8-divinylcyclotetrasiloxane 5127
covered magnetic stir bar. The flask was placed in an ice bath,
while II (30 g, 0.144 mol) was added via a 50 mL syringe slowly
over 2 h. The solution was allowed to stir at room temperature
until no more gas bubbles evolved. The solution was dried over
anhydrous MgSO4 and filtered, and the volatile solvents were
removed by evaporation under reduced pressure. In this way,
36 g, 99% yield of III was obtained. 1H NMR δ: 0.095 (s, 6H),
0.127 (s, 12H), 5.25 (m, 2H). 13C NMR δ: 0.375, 0.89. 29Si NMR
δ: -19.9 (s, 1Si), -10.8 (s, 2Si). IR ν: 3275 (Si-OH), 2964,
1266 (Si-CH3), 1051 cm-1 (Si-O).
2,2,4,4,6,6-Hexam eth yl-8,8-divin ylcyclotetr asiloxan e (I).
Diethyl ether (100 mL) and triethylamine (11.5 g, 114 mmol)
were placed in a 250 mL three-neck round-bottom flask
equipped with two pressure-equalizing addition funnels and
a Tru-bore stirrer equipped with a Teflon paddle which was
attached to a mechanical stirrer. Diethyl ether (15 mL) and
III (6.7 g, 28 mmol) were placed in one addition funnel. Diethyl
ether (15 mL) and divinyldichlorosilane (4.3 g, 28 mmol) were
placed in the other. Both solutions were added dropwise over
1 h. The reaction was allowed to stir for 3 h at room
temperature. The reaction mixture was then washed with
brine and water until it was neutral. The solution was dried
over anhydrous MgSO4 and filtered, and the volatile solvent
was removed by evaporation under reduced pressure. The
solution was then distilled through a 5 cm vacuum jacketed
distillation column, which was packed with glass saddles. A
fraction bp 109 °C/20 mm, 5 g, 56% yield was obtained. 1H
NMR δ: 0.092 (s, 6H), 0.121 (s, 12H), 5.874 (dd, 1H, J ) 13.5
and 10 Hz), 6.0315 (d, 1H, J ) 13.5 Hz), 6.035 (d, 1H, J ) 10
Hz). 13C NMR δ: 0.82, 0.854, 134.5, 135.0. 29Si NMR δ: -48.2
(s, 1Si), -18.8 (s, 1Si), -18.0 (s, 2Si). IR ν: 3057, 2964, 1597
(CdC), 1074 cm-1 (Si-O). GC/MS m/e (rel. abundance): 320
(5%) M+, 305 (100%) (M-15)+, 277 (15%), 251 (17%). High-
resolution mass spectra. Calcd for C10H24O4Si4: 320.07517.
Found: 320.0748.
significant amounts of monomeric cyclosiloxanes were
detected. These were characterized by GC/MS.
Exp er im en ta l Section
Sp ectr oscop ic An a lysis. 1H, 13C, and 29Si NMR spectra
of 5% w/v CDCl3 solutions were obtained on a Bruker AMX-
500 MHz spectrometer. 13C NMR spectra were obtained with
broad-band proton decoupling. 1H and 13C spectra were
internally referenced to TMS and residual CHCl3. A hetero-
nuclear gated decoupling pulse sequence (NONOE) with a 60
s delay was used to acquire 29Si NMR spectra. These were
referenced to internal TMS. IR spectra of neat liquid films on
NaCl plates were recorded on a Perkin-Elmer Spectrum 2000
FT-IR spectrometer.
Gel permeation chromatographic (GPC) analysis of the
molecular weight distribution (Mw/Mn) of the polymers carried
out on a Waters system equipped with a 501 refractive index
detector. Two 7.8 mm × 300 mm Styragel HT 6E and HMW
6E columns in series were used for the analysis. The eluting
solvent was toluene at a flow rate of 0.6 mL/min. Toluene was
utilized since the refractive indexes of THF and our siloxane
polymers are quite close. The retention times were calibrated
against known monodisperse polystyrene standards: 929 000,
114 200, 13 700, and 794 g/mol.
Thermogravimetric analysis (TGA) of the copolysiloxanes
was carried out on a Shimadzu TGA-50 instrument with a flow
rate of 40 cm3/min of nitrogen or air. The temperature was
increased at a rate of 4 °C/min from 25 to 800 °C. Glass
transition temperatures (Tg’s) of the copolymers were deter-
mined on a Perkin-Elmer DSC-7 or on a Shimadzu DSC-50.
The differential scanning calorimeters (DSC) were calibrated
against the heat of transition (-87.06 °C) and the melting
point of cyclohexane (6.54 °C)9 as well as from the Tg of PDMS
(-125 °C).10 Samples were equilibrated at -150 °C for 30 min.
Thermal analysis was then carried out by increasing the
temperature from -150 to 50 °C at a rate of 10 °C/min.
Low-resolution mass spectra were obtained by GC/MS on a
Hewlett-Packard 5890 series II GC equipped with a Hewlett-
Packard 5971 series mass selective detector and a 30 m DB5
capillary column. High-resolution mass spectra were acquired
at the University of California at Riverside Mass Spectroscopy
Facility on a VG ZAB2SE instrument. Exact masses were
calibrated determined against known mass peaks of perfluo-
rokerosene.
Dimethyldichlorosilane, divinyldichlorosilane, and 1,1,3,3-
tetramethyldisiloxane were obtained from Gelest. Pd/C (5%)
and phosphazene base, P4-t-Bu (1.0 M in n-hexane), were
purchase from Fluka. THF, triethylamine, and diethyl ether
were obtained from Aldrich. Triethylamine was dried over
NaOH pellets. Diethyl ether was dried over activated 4 Å
molecular sieves. 1,1,3,3-Tetramethyldisiloxane was purified
by distillation. Other chemicals were used as obtained.
All reactions were run in flame-dried glassware under
argon. Teflon-covered magnetic stir bars were used to agitate
the reactions.
An ion ic P olym er iza tion of I, Cop oly(d im eth ylsilox-
a n e/d ivin ylsiloxa n e) (3:1 Mole Ra tio). I (1.5 g, 4.54 mmol)
was placed in a 15 mL Ace pressure tube which was sealed
with an O-ring and a threaded Teflon cap. P4-t-Bu superbase
(3.1 mg, 5 µL, 5 µmol) was added. Argon was bubbled through
the solution for 1 min, and the tube was then sealed. The
polymerization was allowed to proceed at 80 °C for 20 min.
Trimethylchlorosilane (8.85 mg, 10 µL, 79 µmol) and triethyl-
amine (7.26 mg, 10 µL, 72 µmol) were added sequentially to
quench the reaction. The polymer was precipitated three times
from diethyl ether/methanol and was then dried under vacuum.
In this way, 1.2 g, 80% yield, of polymer with Mw/Mn ) 87 300/
1
43 500 and Tg ) -125 °C was obtained. H NMR δ: 0.12 (s,
9H), 0.14 (s, 9H), 5.88-5.93 (m, 2H), 6.05-6.07 (m, 4H). 13C
NMR δ: 1.07, 1.08, 1.13, 1.21, 134.20, 134.21, 134.28, 134.37,
134.44, 134.45, 134.53, 134.60, 134.70, 134.72, 134.99, 135.05,
135.07, 135.16, 135.23, 135.24, 135.31, 135.33. 29Si NMR δ:
-50.12, -50.11, -50.07, -50.04, -50.01, -49.99, -49.97,
-49.93, -49.92, -49.60, -49.58, -49.55, -49.53, -49.50,
-49.43, -49.38, -49.02, -49.00, -48.93, -48.92, -21.89,
-21.86, -21.83, -21.75, -21.73, -21.61, -21.60, -21.00,
-20.98, 20.95, -20.88, -20.86, -20.74, -20.05, -20.02,
1,1,3,3,5,5-H exa m et h ylt r isiloxa n e (II).11 1,1,3,3-Tetra-
methyldisiloxane (281 g, 2.1 mol) and FeCl3‚6H2O (1 g, 3.7
mmol) were placed in a 500 mL two-neck round-bottom flask
equipped with a rubber septum, a pressure-equalizing addition
funnel. HCl gas was bubbled through the solution while
dimethyldichlorosilane (127 g, 1 mol) was added dropwise from
an addition funnel over 3 h. The reaction was stirred for 3 h
at room temperature (rt). The mixture was then distilled
through a 10 cm vacuum jacketed distillation column packed
with glass saddles. A fraction bp 127 °C/760 mm, 80 g, 38%
-19.92, -19.79. IR v: 2963, 1597, 1406, 1260, 1028 cm-1
.
An a lysis of Meth a n ol-Solu ble Ma ter ia l. After evapora-
tion of the methanol, approximately 0.3 g, 20% yield, of residue
was obtained. This material was analyzed by a combination
of GPC and GC/MS. Soluble oligomers, ∼4% yield, Mw/Mn
)
3700/2640 were obtained. In addition, a series of cyclotetra-,
cyclopenta-, and cyclohexasiloxanes (∼16% yield) were identi-
fied by GC/MS from their (M-15)+ ions. In this way, the
following isomers of cyclosiloxanes containing D and V units
were identified: octamethylcyclotetrasiloxane (D4) (9.4%), I
(D3V) (20.3%), decamethylcyclopentasiloxane (D5) (7.2%), D2V2
(6.7%), D4V (26.9%), D3V2 (16.4%), D2V3 (1.7%), dodecameth-
ylcyclohexasiloxane (D6) (1.5%), D5V (7.2%), D4V2 (2.7%). Yields
reported here have been normalized so that the total amount
of cyclosiloxanes equals 100%.
1
yield was obtained. H NMR δ: 0.065 (s, 6H), 0.191 (d, 12H,
J ) 2.5 Hz), 4.70 (m, 2H). 13C NMR δ: 0.64. 29Si NMR δ:
-17.56 (s, 1Si), -6.74 (d, 2Si, J Si-H ) 2 Hz). IR ν: 2128 (Si-
H) and 1057 cm-1 (Si-O). GC/MS m/e (relative abundance):
207 (18%) (M-1)+, 193 (100%) (M-15)+, 133 (25%), 119 (16%),
103 (10%).
1,5-Dih yd r oxyh exa m eth yltr isiloxa n e (III).12 Deionized
water (8.0 g, 0.44 mol), THF (50 mL), and Pd/C (50 mg) were
placed in a 250 mL Erlenmeyer flask equipped with a Teflon-
Ca tion ic P olym er iza tion of I, Cop oly(d im eth ylsilox-
a n e/d ivin ylsiloxa n e). I (0.5 g, 1.56 mmol) was placed in a
test tube which was sealed with a rubber septum. Dichlo-