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The polymerization of unsaturated organosilicon compounds
THE P O L Y M E R I Z A T I O N OF UNSATURATED ORGANOSILICON COMPOUNDS * K. A. ANDRIANOV and A. K. DABAGOVA Institute of Elements and Organic Compounds of the U.S.S.R. Academy of Sciences (Received 9 May 1959)
[T is reported in the literature that the vinyl and allyl derivatives of organosilicon compounds do not readily polymerize, irrespective of the position of the double bond relative to the silicon atom and that in the presence of peroxides at a pressure of up to 6000 atm and at about 130°C low molecular weight polymers are formed as viscous oils [1]. I t has been demonstrated by ourselves and by other authors too that organosilicon compounds containing a methacryl group are appreciably more reactive and polymerize in the presence of peroxide initiators to yield solid, vitreous polymers [2-5]. The present paper relates to a study of the polymerization of organosilicon compounds containing a methacryl or a carboxyallyl group, and compounds containing the two groups simultaneously. The influence of the distance between the mcthacryl groups on polymerizability was examined on samples cf methacryl derivatives of organosilicon compounds. The compounds selected for polymerization were: 1,2-di-(carboxyallyl methyl)tetramethyl disiloxane [CH~----CH'CH20COOCH2Si(CHa)2120, 1-methacrylate methyl-2-carboxyallylate methyl tetramethyl disiloxane CH2----C(CH3)COOCH2Si (CH3)2OSi(CHa)2CH2OCOOCH2CH----CH2, methacrylate methyl pentamethyl disiloxane CH2=C(CHa)COOCH2Si(CH3)2OSi(CH3) 3, 2-methacrylate methyl heptamethyl trisiloxane (CH3)aSiOSi(CH3)(CH2OCOC(CH3)=CH2)OSi(CH3)a, and dimethacryl derivatives of di-, tri-, tetra- and pentasiloxanes of the general formula CH2----C(CH3)COOCH2Si(CH3)2[O--Si(CHa)2]nCH2OCOC(CHa)----CH., where ~:=1, 2, 3, 4. The synthesis of these compounds has been reported earlier [1, 6]]. Polymerization was accomplished in dilatometers of about 5 ml capacity at 64.5°C in the presence of benzoyl peroxide. The rate of polymerization was determined from the decrease in volume as a function of the time to attainment of the gelling point. It follows from our experimental findings that 1,2-di-(carboxyallylate methyl)-tetramethyl disiloxane readily polymerizes (Fig. 1) but its rate is less than * Vysokomol. soedin, h No. 6, 930-933, 1959. 313
314
K . A . ANDRIANOV and A. K. DABAGOVA
that of 1,2-di-(methacrylate methyl)-tetramethyl disiloxane (Fig. 4, curve 1). A compound containing simultaneously a methacryl and a carboxyallyl group also polymerizes easily with 1-methacrylate methyl -2-carboxyallylate methyl 20 .~.
i//~.t
2
/ /
l,g
I
i
I
?
3
[
5
I
I
7
I
9
f
,
J
/1
Time (hr)
FIG. 1. Polymerization of' carboxyallyl e ~ r s (3~o benzoyl peroxide): (1) 1,2-di-(carboxyallylate methyl)tetramethyl disiloxane (2) dicarboxyallyl ester of diethylene glycol. tetramethyl disiloxane (Fig. 2, curve 1) have a faster rate than 1,2-di-(carboxyaUylate methyl)-tetramethyl disfloxane and 1,2-di-(methacrylate methyl)tetramethyl disfloxane. This phenomenon is obviously attributable to the occur!
i Io
Z0 Time (rain)
30
FIG. 2. Polymerization of compounds containing both a carboxyallyl and a methacryl group (0.01% benzoyl peroxide): (1) 1-methacrylate methyl-2-carboxyallylate methyl tetramethyl disiloxane. (2) methacryl carboxyallyl ester of diethylene glycol. rence of oriented polarization in the vicinity of the disposed polar groups. Comparison of the unsaturated organosilieon compounds, e.g. 1,2-di-(earboxyallylate methyl)-tetramethyl disiloxane (CH2:CHCH20C00CH~SJ(CH3)~)20 , 1-carboxyaUylate methyl-2-methacrylate methyl tetramethyl disiloxane and 1,2-di-
The polymerization of unsaturated organosilicon compounds
315
(methacrylate methyl)-tetramethyl disiloxane with the corresponding organic compounds of diethylene glycol, viz. dicarboxyallyl ester (CH2=CHCH~OC OOCHeCH~)eO methacryl carboxyallyl ester CH2=CHCH2OCOOCH2CH2OCH 2 CH2OCOC(CHa)=CH2, and dimethacrylic ester (CH2-C(CH3)COOCH2CHe)20, disclosed that -Si(CH3)~: is located on the carbon atom combined with the methacryl or carboxyallyl group in place of the -CH 2- group. By comparing the curves for the polymerization processes of the above-mentioned organic and organosilicon compounds (Fig. 1, 2 and 3) the influence of the dimethylsilyl group on the behaviour of the polymerization process can be accounted for. Furthermore the comparison shows that the mcthacryl organosilicon compounds polylnerize far more slowly than their organic analogues (Fig. 4, curves 1 and 6, 2 and 5). Although the polymerization rate of 1,2-di(carboxyallylate methyl)-teiramethyl disiloxane is less than that of the biscarboxyallyl ester of diethylene glycol (Fig. 1, curve 2) it is still close to the polymerization rate of its organic analogue. It is apparent from the experimental findings on the polymerization of compounds containing a methacryl and a carboxyl group simultaneously that 1-methacrylate methyl-2-carboxyallyl methyl disiloxane polymerizes more readily than the methacryl carboxyallyl ester of diethylene glycol. Thus in the polymerization of dimethacryl derivatives
4.0
[
3,o I
f
aJ
R~ e
1.0
1
3
5
7
g
#
13
I5
Time (hr)
b'l,. 3. Polymerization of methacryl derivatives of the siloxane series (0.1% benzoyl peroxide): (1) 1,2-di-(methacrylate methyl)-tetramethyl disiloxane; (2) 1,3-di-(methaerylate methyl)-hexamethyltrisiloxane; (3) 1,4-di-(methacrylate methyl)-octam~thyl tetrasiloxane; (4) 1,5-di-(mcthacrylate methyl)-decamethyl pentasiloxane; (5) dimethacryl ester of triethylene glycol; (6) dimethyacryl ester of diethylene glycol. of the siloxanes the silicon atom exerts a noticeable inhibiting effect that is substantially weaker in the polymerization of a dicarboxyallyl ester of disiloxane and which totally disappears in the polymerization of l-methacrylate methyl -2-carboxyallylate methyltetralnethyl disfloxane.
316
K . A . ANDRIA~OVand A. K. DABAt~OVA
The results found from the polymerization of methacryl derivatives of siloxanes with varying distances between the methacryl groups (Fig. 3 curves 1, 2, 3, 4) reveal great differences in the polymerization rates: 1,2-di-(methacrylate methyl)-tetramethyl disiloxane (curve 1) polymerizes more slowly than the 1,3-, 1,4-, and 1,5-dimethacryl derivatives of the tri-, tetra-, and pentasiloxanes. The polymerization rate of 1,3-, 1,4-, and 1,5-dimethacrylate methyl tri-, tetraand pentasiloxanes decreases inversely with the distance between the methacryl groups, simultaneously accompanied by an increase in the induction period (curves 2, 3 and 4). This appears to stem from the mechanism that is operative for the organic analogues [7, 8] and which is governed by a steric factor. It follows from the experimental results (Fig. 4) that the monomethacryl derivatives of the siloxane series also polymerize readily and here the rate for
•~
2
4
8
8
tO
12
Ti~e (hr) FI(~. 4. Polymerization of monomethaeryl derivatives of di- and trisiloxanes (0.1% benzoyl peroxide). (1) methaerylate methyl pentamethyl disiloxane; (2) 2-methacrylate methyl heptamethyl trisiloxane. TABLE 1. THE COMPOSITIONOF THE PRODUCTS OF POLYMERIZATION
Original monomer
1,2 -di- (methacrylmethyl) -tetramethyl-disiloxane 1,3-di- (inethaerylmethyl)-hexamethyl trisiloxane 1,4-di-(methacrylmethyl)-octamethyl tetrasiloxane 1,5-di-(methacrylmethyl)-decamethyl pentasiloxane 1,2-di-(eaxboxiallilate-methyl) tetramethyl-disiloxane 1-methacrylmethyl-2-carboxiallilatemethyl-tetramethyldisiloxane
Content of monomer
Content of ~olymer (%)
(%)
soluble
non-soluble
4.8
0.00
95.1
6.60
0.o8
94.32
5"90
0~35
93.76
5"47
0"16
94.36
36"70
0"08
63.29
23-20
0"03
76.77
2-methacrylate methyl heptamethyl trisiloxane (curve 2) is faster than the rate for methacrylate methyl pentamethyl disiloxane (curve 1). All the polymers were solid, vitreous products. The polymers prepared from the tetrafunctional organosilicon compounds were studied for the content of insoluble and
The polymerization of unsaturated organosi|icon compounds
317
soluble high molecular compounds. For this purpose weighed samples (1-1.5 g) of the polymers, heated at reaction temperature for 50 hr, were first treated with sulphuric ether in a Scxhlet apparatus to extract the monomer, and then with acetone to remove the soluble polymer. Our experimental findings (listed in the Table) show that the conversion for the dimethacryl derivatives of the siloxane series is 95-94 per cent; for the compounds containing a carboxyallyl group, 63-77 per cent: for the insoluble polymers in the case of the carboxyallyl derivatives it is governed by the incompleteness of polynmrization under the given reaction conditions. CONCLUSIONS
(1) The polymerization of unsaturated organosilicon compounds is studied. Compounds which contain methacryl groups, carboxyallyl groups and also carboxyallyl and methacryl groups simultaneously in the hydrocarbon radical located on the silicon atom readily po]ymerize in the presence of peroxide initiators. (2) Of the compounds studied the Oimethylsilyl group has an extremely pronounced inhibiting influence on the polymerization of the dimethacryl derivatives of di- and trisiloxane. (3) The polymerization rate of the dimethacryl derivatives of the siloxane series diminishes from 1,3-di-(methacrylate methyl)-hexamethyl trisiloxane to [,5-di-(methacrylate methyl)-decamethyl pentasiloxane and 1,2-di-(methacrylate methyl)-tetramethyl disiloxane polymerizes less readily than its homologues. Translated by G. CAMERON REFERENCES L A . D . PETROV, P . M . POLYAKOVA, A . A . SAKHAROVA, V.V. KORSHAK, V . F . MIRONOV and G . I . NIKISHIN, Dokl. Akad. Nauk SSSR 99: 785, 1954 2. K . A . ANDRIANOV, N.S. LEZNOV and A . K . DABAGOVA, Izv. Akad. Nauk SSSR Otdel. khim. nauk 459, 1957 3. R . L . M E R K E R and G . E . NOEL, J. Organ. Chem. 21: 1537, 1956 4. U . S . P a t e n t 2793223, 21: May 1957 5. R . L . M E R K E R and M . I . SCOTT, J. Polymer Sei. 25: 115, 1957 6. K . A . ANDRIANOV and A . K . DABAGOVA, Dokl. Akad. Nauk SSSR 1 1 9 : 1 1 4 9 , 1 9 5 8 7. A . A . BERLIN, E. F. RODIONOVA and A. K. DABAGOVA, Sbornik statei po obshchei khimii. {Symposium on General Chemistry.) No. 2, 1554, 1953
8. A. A. BERLIN, A. K. DABAGOVA and E. F. RODIONOVA, Sbornik statei po obshchei khimii. (Symposium on General Chemistry.) No. 2, 1560, 1953
21 Polymer "2
[T is reported in the literature that the vinyl and allyl derivatives of organosilicon compounds do not readily polymerize, irrespective of the position of the double bond relative to the silicon atom and that in the presence of peroxides at a pressure of up to 6000 atm and at about 130°C low molecular weight polymers are formed as viscous oils [1]. I t has been demonstrated by ourselves and by other authors too that organosilicon compounds containing a methacryl group are appreciably more reactive and polymerize in the presence of peroxide initiators to yield solid, vitreous polymers [2-5]. The present paper relates to a study of the polymerization of organosilicon compounds containing a methacryl or a carboxyallyl group, and compounds containing the two groups simultaneously. The influence of the distance between the mcthacryl groups on polymerizability was examined on samples cf methacryl derivatives of organosilicon compounds. The compounds selected for polymerization were: 1,2-di-(carboxyallyl methyl)tetramethyl disiloxane [CH~----CH'CH20COOCH2Si(CHa)2120, 1-methacrylate methyl-2-carboxyallylate methyl tetramethyl disiloxane CH2----C(CH3)COOCH2Si (CH3)2OSi(CHa)2CH2OCOOCH2CH----CH2, methacrylate methyl pentamethyl disiloxane CH2=C(CHa)COOCH2Si(CH3)2OSi(CH3) 3, 2-methacrylate methyl heptamethyl trisiloxane (CH3)aSiOSi(CH3)(CH2OCOC(CH3)=CH2)OSi(CH3)a, and dimethacryl derivatives of di-, tri-, tetra- and pentasiloxanes of the general formula CH2----C(CH3)COOCH2Si(CH3)2[O--Si(CHa)2]nCH2OCOC(CHa)----CH., where ~:=1, 2, 3, 4. The synthesis of these compounds has been reported earlier [1, 6]]. Polymerization was accomplished in dilatometers of about 5 ml capacity at 64.5°C in the presence of benzoyl peroxide. The rate of polymerization was determined from the decrease in volume as a function of the time to attainment of the gelling point. It follows from our experimental findings that 1,2-di-(carboxyallylate methyl)-tetramethyl disiloxane readily polymerizes (Fig. 1) but its rate is less than * Vysokomol. soedin, h No. 6, 930-933, 1959. 313
314
K . A . ANDRIANOV and A. K. DABAGOVA
that of 1,2-di-(methacrylate methyl)-tetramethyl disiloxane (Fig. 4, curve 1). A compound containing simultaneously a methacryl and a carboxyallyl group also polymerizes easily with 1-methacrylate methyl -2-carboxyallylate methyl 20 .~.
i//~.t
2
/ /
l,g
I
i
I
?
3
[
5
I
I
7
I
9
f
,
J
/1
Time (hr)
FIG. 1. Polymerization of' carboxyallyl e ~ r s (3~o benzoyl peroxide): (1) 1,2-di-(carboxyallylate methyl)tetramethyl disiloxane (2) dicarboxyallyl ester of diethylene glycol. tetramethyl disiloxane (Fig. 2, curve 1) have a faster rate than 1,2-di-(carboxyaUylate methyl)-tetramethyl disfloxane and 1,2-di-(methacrylate methyl)tetramethyl disfloxane. This phenomenon is obviously attributable to the occur!
i Io
Z0 Time (rain)
30
FIG. 2. Polymerization of compounds containing both a carboxyallyl and a methacryl group (0.01% benzoyl peroxide): (1) 1-methacrylate methyl-2-carboxyallylate methyl tetramethyl disiloxane. (2) methacryl carboxyallyl ester of diethylene glycol. rence of oriented polarization in the vicinity of the disposed polar groups. Comparison of the unsaturated organosilieon compounds, e.g. 1,2-di-(earboxyallylate methyl)-tetramethyl disiloxane (CH2:CHCH20C00CH~SJ(CH3)~)20 , 1-carboxyaUylate methyl-2-methacrylate methyl tetramethyl disiloxane and 1,2-di-
The polymerization of unsaturated organosilicon compounds
315
(methacrylate methyl)-tetramethyl disiloxane with the corresponding organic compounds of diethylene glycol, viz. dicarboxyallyl ester (CH2=CHCH~OC OOCHeCH~)eO methacryl carboxyallyl ester CH2=CHCH2OCOOCH2CH2OCH 2 CH2OCOC(CHa)=CH2, and dimethacrylic ester (CH2-C(CH3)COOCH2CHe)20, disclosed that -Si(CH3)~: is located on the carbon atom combined with the methacryl or carboxyallyl group in place of the -CH 2- group. By comparing the curves for the polymerization processes of the above-mentioned organic and organosilicon compounds (Fig. 1, 2 and 3) the influence of the dimethylsilyl group on the behaviour of the polymerization process can be accounted for. Furthermore the comparison shows that the mcthacryl organosilicon compounds polylnerize far more slowly than their organic analogues (Fig. 4, curves 1 and 6, 2 and 5). Although the polymerization rate of 1,2-di(carboxyallylate methyl)-teiramethyl disiloxane is less than that of the biscarboxyallyl ester of diethylene glycol (Fig. 1, curve 2) it is still close to the polymerization rate of its organic analogue. It is apparent from the experimental findings on the polymerization of compounds containing a methacryl and a carboxyl group simultaneously that 1-methacrylate methyl-2-carboxyallyl methyl disiloxane polymerizes more readily than the methacryl carboxyallyl ester of diethylene glycol. Thus in the polymerization of dimethacryl derivatives
4.0
[
3,o I
f
aJ
R~ e
1.0
1
3
5
7
g
#
13
I5
Time (hr)
b'l,. 3. Polymerization of methacryl derivatives of the siloxane series (0.1% benzoyl peroxide): (1) 1,2-di-(methacrylate methyl)-tetramethyl disiloxane; (2) 1,3-di-(methaerylate methyl)-hexamethyltrisiloxane; (3) 1,4-di-(methacrylate methyl)-octam~thyl tetrasiloxane; (4) 1,5-di-(mcthacrylate methyl)-decamethyl pentasiloxane; (5) dimethacryl ester of triethylene glycol; (6) dimethyacryl ester of diethylene glycol. of the siloxanes the silicon atom exerts a noticeable inhibiting effect that is substantially weaker in the polymerization of a dicarboxyallyl ester of disiloxane and which totally disappears in the polymerization of l-methacrylate methyl -2-carboxyallylate methyltetralnethyl disfloxane.
316
K . A . ANDRIA~OVand A. K. DABAt~OVA
The results found from the polymerization of methacryl derivatives of siloxanes with varying distances between the methacryl groups (Fig. 3 curves 1, 2, 3, 4) reveal great differences in the polymerization rates: 1,2-di-(methacrylate methyl)-tetramethyl disiloxane (curve 1) polymerizes more slowly than the 1,3-, 1,4-, and 1,5-dimethacryl derivatives of the tri-, tetra-, and pentasiloxanes. The polymerization rate of 1,3-, 1,4-, and 1,5-dimethacrylate methyl tri-, tetraand pentasiloxanes decreases inversely with the distance between the methacryl groups, simultaneously accompanied by an increase in the induction period (curves 2, 3 and 4). This appears to stem from the mechanism that is operative for the organic analogues [7, 8] and which is governed by a steric factor. It follows from the experimental results (Fig. 4) that the monomethacryl derivatives of the siloxane series also polymerize readily and here the rate for
•~
2
4
8
8
tO
12
Ti~e (hr) FI(~. 4. Polymerization of monomethaeryl derivatives of di- and trisiloxanes (0.1% benzoyl peroxide). (1) methaerylate methyl pentamethyl disiloxane; (2) 2-methacrylate methyl heptamethyl trisiloxane. TABLE 1. THE COMPOSITIONOF THE PRODUCTS OF POLYMERIZATION
Original monomer
1,2 -di- (methacrylmethyl) -tetramethyl-disiloxane 1,3-di- (inethaerylmethyl)-hexamethyl trisiloxane 1,4-di-(methacrylmethyl)-octamethyl tetrasiloxane 1,5-di-(methacrylmethyl)-decamethyl pentasiloxane 1,2-di-(eaxboxiallilate-methyl) tetramethyl-disiloxane 1-methacrylmethyl-2-carboxiallilatemethyl-tetramethyldisiloxane
Content of monomer
Content of ~olymer (%)
(%)
soluble
non-soluble
4.8
0.00
95.1
6.60
0.o8
94.32
5"90
0~35
93.76
5"47
0"16
94.36
36"70
0"08
63.29
23-20
0"03
76.77
2-methacrylate methyl heptamethyl trisiloxane (curve 2) is faster than the rate for methacrylate methyl pentamethyl disiloxane (curve 1). All the polymers were solid, vitreous products. The polymers prepared from the tetrafunctional organosilicon compounds were studied for the content of insoluble and
The polymerization of unsaturated organosi|icon compounds
317
soluble high molecular compounds. For this purpose weighed samples (1-1.5 g) of the polymers, heated at reaction temperature for 50 hr, were first treated with sulphuric ether in a Scxhlet apparatus to extract the monomer, and then with acetone to remove the soluble polymer. Our experimental findings (listed in the Table) show that the conversion for the dimethacryl derivatives of the siloxane series is 95-94 per cent; for the compounds containing a carboxyallyl group, 63-77 per cent: for the insoluble polymers in the case of the carboxyallyl derivatives it is governed by the incompleteness of polynmrization under the given reaction conditions. CONCLUSIONS
(1) The polymerization of unsaturated organosilicon compounds is studied. Compounds which contain methacryl groups, carboxyallyl groups and also carboxyallyl and methacryl groups simultaneously in the hydrocarbon radical located on the silicon atom readily po]ymerize in the presence of peroxide initiators. (2) Of the compounds studied the Oimethylsilyl group has an extremely pronounced inhibiting influence on the polymerization of the dimethacryl derivatives of di- and trisiloxane. (3) The polymerization rate of the dimethacryl derivatives of the siloxane series diminishes from 1,3-di-(methacrylate methyl)-hexamethyl trisiloxane to [,5-di-(methacrylate methyl)-decamethyl pentasiloxane and 1,2-di-(methacrylate methyl)-tetramethyl disiloxane polymerizes less readily than its homologues. Translated by G. CAMERON REFERENCES L A . D . PETROV, P . M . POLYAKOVA, A . A . SAKHAROVA, V.V. KORSHAK, V . F . MIRONOV and G . I . NIKISHIN, Dokl. Akad. Nauk SSSR 99: 785, 1954 2. K . A . ANDRIANOV, N.S. LEZNOV and A . K . DABAGOVA, Izv. Akad. Nauk SSSR Otdel. khim. nauk 459, 1957 3. R . L . M E R K E R and G . E . NOEL, J. Organ. Chem. 21: 1537, 1956 4. U . S . P a t e n t 2793223, 21: May 1957 5. R . L . M E R K E R and M . I . SCOTT, J. Polymer Sei. 25: 115, 1957 6. K . A . ANDRIANOV and A . K . DABAGOVA, Dokl. Akad. Nauk SSSR 1 1 9 : 1 1 4 9 , 1 9 5 8 7. A . A . BERLIN, E. F. RODIONOVA and A. K. DABAGOVA, Sbornik statei po obshchei khimii. {Symposium on General Chemistry.) No. 2, 1554, 1953
8. A. A. BERLIN, A. K. DABAGOVA and E. F. RODIONOVA, Sbornik statei po obshchei khimii. (Symposium on General Chemistry.) No. 2, 1560, 1953
21 Polymer "2