760 J. Chin. Chem. Soc., Vol. 54, No. 3, 2007
Mahkam et al.
Free radical terpolymerization of the resulting silyl
monomers with methacrylic acid (MAA) in the various ra-
tios produced silyl pendant polymers. The -COOH groups
in the polymers can be employed for immobilization of en-
zymes via covalent bonding when necessary.
was chromatographed over silica gel by hexane to yield
(70%) of TESiMSt. IR (neat, cm-1): 3026, 2958, 1610,
1450, 1257, 887. 1H-NMR (CDCl3, ppm) d 0.57 (q, 7.9 Hz,
6H, SiCH2-CH3), 0.92 (t, 7.9 Hz, 9H, SiCH2-CH3), 2.14 (s,
2H, Ar-CH2), 5.23 (d, 6 Hz, 1H, CH=CH2), 5.73 (d, 12 Hz,
1H, CH=CH2), 6.71 (q, 12 Hz, 1H, CH=CH2), 7.02 (d, 7.9
Hz, 2H, Ar), 7.31 (d, 7.9 Hz, 2H, Ar).
EXPERIMENTAL
Synthesis of 4-dimethylsilylmethylstyrene: (DMSiMSt)
After preparation of 4-vinylbenzyllithium (10 mmol)
in THF solution (10 mL), a solution of an excess amount of
dimethylsilyl chloride (36 mmol) in THF (15 mL) was
dropped from the isobaric-type dropping funnel into the
mixture for 3 h at 0 °C. After the reaction, low boiling ma-
terials were evaporated and the residue was chromato-
graphed over silica gel by hexane to yield (90%) of
DMSiMSt. IR (neat, cm-1): 3020, 2960, 2115, 1605, 1430,
1254, 897. 1H-NMR (CDCl3, ppm) d 0.15 (d, 6H, SiCH3),
1.6 (s, 3H, Ar-CH2), 4.1 (m, 1H, SiH), 5.12 (d, 6 Hz, 1H,
CH=CH2), 5.67 (d, 12 Hz, 1H, CH=CH2), 6.67 (q, 12 Hz,
1H, CH=CH2), 7.16 (d, 7.6 Hz, 2H, ArH), 7.28 (d, 7.6 Hz,
2H, ArH).
Synthesis of monomers and copolymerization were
carried out under dry argon to exclude oxygen and moisture
from the reaction systems.
Materials
The methacryloyloxyethyl ester of Et3Si (TESiEMA)
was prepared by the method described in the literature.9
The solvents and reagents were purchased from Merck and
Fluka Co. THF was dried by the standard method and Et3SiCl,
(CH3)2HSiCl and 4-methylstyrene used as received. Initia-
tor of azobisisobutyronitrile (AIBN) was purified by crys-
tallization from methanol.
Measurements
1H-NMR spectra were recorded on a Bruker 400 AC
spectrometer in CDCl3. The IR spectra were recorded on a
Shimadzu FT IR-408 spectrophotometer. The DSC curves
were obtained on a TGA/SDTA 851 calorimeter at heating
and cooling rates of 10 °C/min in air.
Copolymerization
Terpolymer (MAA, TESiEMA and TESiMSt) (P-1)
and Terpolymer (MAA, TESiEMA and DMSiMSt) (P-2)
in two different molar ratio was synthesized as in the fol-
lowing general method. In three pyrex glass ampoules, a
mixture (MAA, TESiEMA and TESiMSt: 1:1:1), (MAA,
TESiEMA and DMSiMSt: 1:1:1) and (MAA, TESiEMA
and DMSiMSt: 1:2:1) by using azobisisobutyronitrile
(AIBN) as initiator ([I] = 0.02 M) was dissolved in dioxane,
respectively. Then the ampoules were degassed, sealed un-
der vacuum and maintained at 70 °C in a water bath and
shaken by a shaker machine for about 60 h. Then the vis-
cous solutions were poured from the ampoules into 100 mL
of cooled methanol, separately. The precipitates were col-
lected and washed with methanol several times and dried
under vacuum at room temperature to give 85% of terpoly-
mer P-1, 91% of terpolymer P-2 and 95% of P-3. (Scheme
II).
Molecular weight of the polymers was determined in
formic acid by a cryometric method using a Knauer cryo-
scopic unit analysis instrument. Polyethylene glycols (with
molecular weights 4000, 10000 and 15000) were used to
calibrate the instrument.
Synthesis of 4-triethylsilylmethylstyrene: (TESiMSt)
To a stirred THF solution (15.8 mL) of diisopropyl-
amine (2.02 g, 20 mmol), a cyclohexane solution (3 mL) of
n-butyllithium (0.65 g, 10 mmol) was added in a 100 mL
round-bottomed flask equipped with a three-way stop-cock
and an isobaric-type dropping funnel. After stirring for a
few minutes to complete the formation of lithium diisopro-
pylamide, 4-methylstyrene (1.18 g, 10 mmol) was added by
syringe. The color of the mixture turned yellow immedi-
ately. Then a THF solution (11 mL) of triethylsilyl chloride
(1.7 g, 11 mmol) was dropped from the isobaric-type drop-
ping funnel into the mixture for 3 h at 20 °C. After the reac-
tion, low boiling materials were evaporated and the residue
P-1: IR (neat, cm-1): 3423, 2955, 2876, 1733, 1509,
1458, 1261, 830. 1H-NMR (d-DMSO, ppm) d 0.41-0.47 (q,
12H, SiCH2), 0.88 (t, 18H, CH3CH2Si), 1.02-2 (br, CH3,
CH2), 3.55-3.87 (br, 4H, -OCH2-CH2O-), 6.99 (br, Ar-H),
11.97 (br, 1H, -COOH).
P-2: IR (neat, cm-1): 3428, 2951, 2859, 2116, 1727,