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Polyfunctional initiators of radical polymerization and the molecular weight distribution of polymers
2238
N . S . TSVETKOV and R. F. MARKOVSKAYA REI:ER~NCE$
1. V. A. KABANOV, Sb. Kinetika i mekhanizm obrazovaniya prevrasheheniya m~kromolekul (Collected papers. The Kinetics and Mechanism of Formation and Reactions of Macromolecules). p. 25, Izd. "Nauka", 1968 2. V. F. GROMOV, A. MATVEEVA, A. D. ABKIN, P. M. KHOMIKOVSKII and E. I. MIROKI-IINA, Dokl. Akad. Nauk SSSR 179: 374, 1968 3. A. V. RYABOV, Yu. D. SEMCHIKOV and N. N. SLAVNITSKINA, Dokl. Akad. Nauk SSSR 154: 35, 1964 4. V. S. IVANOV, Radiatsionnaya polimerizatsya (Radiation Polymerization). Izd. "Khimiya", 1967 5. A. WEISSBERGER, E. PROSKAUER, J. RIDDICK and E. TOOPS, Organicheskie rastvoriteli (Organic Solvents). Foreign Literature Publishing House, 1958 (Russian translation) 6. U. N. MUSAYEV, A. KARIMOV, R. S. TILLAYEV and K. H. U. USMANOV, Uzb. khim. zh., No. 2, 47, 1972 7. Kh. U. USMA~OV, U. N. MUSAYEV, M. M. MIRKI-IIDOYATOV, A. KARIMOV and M. RAKHIMOVA, International Symposium on Macromolecular Chemistry, p. 861, 1972 9. Kh. S. BAGDASARYAN, Teoriya radikal'noi polimerizatsii (Theory of Radical Polymerization). Izd. "Nauka", 1966 10. N. N. LOGINOVA, Dissertation, 1969 l l . N. N. LOGINA and R. K. GAVURINA, Vysokomol. soyed. B l l : 355, 1969 (Not translated in Polymer Sei. U.S.S.R.)
POLYFUNCTIONAL INITIATORS OF RADICAL POLYMERIZATION AND THE MOLECULAR WEIGHT DISTRIBUTION OF POLYMERS* N. S. TSVETKOV a n d R . F . MARKOVSKAYA I v a n Franko State University, L'vov
(Reeived 28 February 1972) I n the synthesis of polymeric peroxides (PP) of dibasic acids by hetero-phase polycondensation of their diacid chlorides (DAC) with sodium peroxide, the nature of the solvent for the acid chloride has a substantial effect on the yield and molecular weight of the product. I t is shown that in order to increase the yield and molecular weight of a P P a non-polar liquid must be used, in which the P P is insoluble. The MWD of the P P ' s is typical of polymers obtained b y polycondensation, b u t the occurrence of side reactions (especially hydrolysis of the DAC) can alter the MWD curve. During the course of polymerization of styrene and other monomers in the presence of these peroxides the molecular weight of products increases continuously and the MWD becomes narrower. An explanation of these facts, which are associated with multiple recombination of propagating radicals, is given. * Vysokomol. soyed. AI6: No. 9, 1936-1939, 1974.
t)olyfunctional initiators of radical polymerization
2239
TttE polymerization of mono-olefinic compounds, initiated by polymeric peroxides (PP) of aliphatic dibasic acids, is characterized by increase in the molecular weight of the polymeric products as conversion of the monomer proceeds [1-3]. This property of polyfunctional initiators is of much interest for production of polymers of high molecular weight at high rates. The special value of PP's in cases where for one reason or another the monomer does not form polymers of high molecular weight with monofunctional initiators must be emphasized. The present paper discusses a study of the mechanism of formation of macromolecular chains in the presence of a polymeric peroxide as initiator and of the effect of this mechanism on the MWD of the polymer. The polyfunctional initiators used were PP's of various aliphatic acids, the characteristics of which are given in reference [4]. The monomer was styrene. ]~olymeric peroxides of dibasic earboxylic acids were prepared from the corresponding acid chlorides and sodium peroxide, b y heterophase polyeondensation. The acid obJorides were first dissolved in a non-polar liquid and the sodium peroxide in an aqueous sohition of sodium acetate. The conditions of preparation of the PP's have a marked effect on the yield of the product and on its degree of polycondensation. There is no information in the literature that would throw light on the nature of this effect. The reaction between sodium peroxide and an acid chloride is highly exothermic, proceeds at a high rate and is practically completed in a few minutes. To reduce the probability of occurrence of side reactions the preparation was carried out at 0-4 ° . Preliminary investigations showed (Table) that the yield and molecular weight of the P P are most strongly dependent on the solubility of the
'~~'-'~#3-
¢gtj O.2 /0
I
I
20
30
I
z/Op
FIo. I. MoleoLdar weight distribution of the po|yperoxide of pimelio acid. Average
degree Of polyeondensation 9.6; 1, / ' - - e x p e r i m e n t a l curves, 2--theoretical curve. latter in the organic phase. It, is known that the affinity between PP's and non-polar substances varies within wide limits and is dependent on the nature of the hydrocarbon radical between the peroxide groups. In the case of PP's of higher aliphatie acids (from pimelic to 1,16-hexadecadicarboxylie) the yield of the product decreases steadily in the following series of solvents: C C 1 4 > e t h e r > n - h e x a n e > o h l o r o b e n z e n e > b e n z e n e > e h l o r o f o r m . This sequence correlates w i t h the solubility of the PP's in these substances, insoluble PP's (of suoeinic, glutaric, adipic and aromatic dicarboxylic acids) are formed in the same yield in all the reaction mixtures examined. The MWD of the peroxides was studied by precipitation chromatography in a column w i t h a linear temperature gradient of 0.7 deg/cm and successive increase in the thermodynamic quality of the solvent (methanol-benzene). The temperature in the heated zone was
2240
N. S. TSV~TKOV and R. F. MARKOVSKAYA
30¢ and the lower part of the column was water cooled to 10°. For construction of a true picture of the MWD the peroxide samples were divided into a fairly large number of fractions (20-50), varying in their average degree of polycondensation, which were then analysed for the active oxygen content. Figure 1 shows integral and differential curves of the MWD of one sample of the PP from i~imelic acid, prepared in the presence of ether as solvent for the acid chloride. The shape of the differential curve in Fig. 1 is typical of polymers obtained by polyeondensation. The comparatively small deviation of the experimental curve from the curve calculated according to the equation Wn=np2(1 _p),,-1 (n is the number of peroxide linkages in the PP molecule and p the degree of degradation) is evidently due to the heterogeneity of the reaction system. The formation of a polyperoxide as a new phase as it is synthesized results in a narrow MWD. Inhomogeneity of a PP with respect to molecular weight can be increased by side reactions, especially hydrolysis of the acid chloride. E F F E C T O~' THE SOLVENT FOR THE ACID CHLORIDE ON THE Y I E L D OF A POLYMERIC P E R O X I D E
(Reaction temperature -- 0°, time -- 15 min) Acid from which peroxide is derived Azelaie
Adipic
Solvent
CC14 Ether n-Hexane Cyclohexane Chlorobenzerie Benzene Chloroform Chlorobenzene CCI~ Chloroform
Solubility of the peroxide in the organic phase
Yield of peroxide, %
Active oxygen in peroxide, %
i i i p.s
62"7 53"3 55'4 40'5
93"5 93"6 93"4 95"0
19'0 12"6 11"2 45"4 44"8 46"3
86"9 84"1 83"5 95"0 96"2 94"0
i--insoluble, s-soluble, p.s.-partially soluble. The n a t u r e of t h e m o n o m e r unit, the average degree of p o l y c o n d e n s a t i o n a n d t h e M W D of the polymeric p e r o x i d e s used as p o l y m e r i z a t i o n initiators do n o t show a n y m a r k e d effect on the conversion of styrene in p o l y m e r i z a t i o n in bulk (Fig. 2). A t the same time the molecular weight of the p o l y m e r is dir e c t l y p r o p o r t i o n a l to the n u m b e r of peroxide groups in the multffunctional initiator [3, 5]. I n f r a r e d s p e c t r o s c o p y a n d o t h e r m e t h o d s show t h a t f r a g m e n t s o f the P P enter the composition o f the p o l y m e r molecule. The relative c o n t e n t of peroxidic groupings in the macromoleeular p r o d u c t s correlates with the original c o n c e n t r a t i o n of the P P t a k e n as initiator (Fig. 3). D u r i n g the course of :polymerization the free P P decomposes r a p i d l y a n d s u b s e q u e n t initiation occurs b y b r e a k d o w n of the 0 - - O b o n d in f r a g m e n t s o f the p o l y f u n c t i o n a l initiator forming p a r t of new p o l y m e r molecules. This produces conditions in which the n u m b e r of p o l y m e r molecules in the reaction m i x t u r e remains practically unc h a n g e d (assuming, of course, t h a t chain transfer does n o t occur).
Polyfunctional initiators of radical polymerization
2241
I t is interesting to note that the average proportion of carboxylate groups in the polystyrene molecules falls progressively as the original concentration of P P in the reaction mixture is decreased. This indicates that the concentration of P P in the solution affects the primary thermal degradation of the peroxide linkages in it, which is exhibited as change in the degree of decarboxylation. Figure 4 shows MWD curves of polystyrene obtained at various degrees of conversion. The MWD was investigated by precipitative chromatography in a column with a linear temperature gradient of 1.3 deg/cm. The solvent and precilO0
D
2O
J/ I
3
_ IL/\
0"8
a# I
I
g T/me, hr FIo. 2
I
I
15
18
17
Ib"
p,, IlT-z c m -;r
FIG. 3
FIG. 2. Time dependence of the degree of polymerization of styrene: a - - 70 °, initiator concentration 0.0276 base-mole/1.: 1 - - P P of suberic, 2--azelaic, 3--1,16-hexadecadicarboxylic acid; b - - 8 0 °, concentration of P P of pimelie acid 0.50 g/100 ml; degree of polycondensation of the peroxide: 4-- 13.1; 5-- 27.5, 6--44.6. FIG. 3. I n f r a r e d spectra of polystyrene solutions in CC14. Polystyrene prepared in the presence of the P P of azelaic acid at initiator concentrations of: 1--1.00, 2--0.50, 3--0'10, 4--0.01 base-mole/1.
pitant for the polystyrene were benzene and methanol respectively. The rate of addition of solvent was 50 ml/hr. The results show that as the extent of thermal degradation of the P P in the polymerization system increases the average molecular weights increase and the MWD narrows. Determination of the degree of inhomogeneity of the polymer by the Sehulz method, for two polystyrene samples separated at degrees of conversion of 9.4 and 80.3~o, gives numerical values of 0.60 and 0.25 respectively. I t is well known that these effects (increase in molecular weight with simultaneous narrowing of the MWD during the course of polymerization) are found in polymerization by the "living" polymer mechanism. In the presence of a polyfunctional initiator the polystyrene molecules are formed by multistage propagation of the polymer chain [2]. From the statistical
2242
N . S. TSVETKOVand R. F. MARKOVSKAYA
point of view this can be equated to multiple recombination of growing radicals. As a result of this the MWD of the polymer at constant relative rates of chain propagation and termination will be similar to a Schulz distribution [6]. The ratio M w / M n can be interpreted in terms of the "average number of recombinations" resulting in formation of " d e a d " chains [7]. For.the polystyrene samples mentioned above the average numbers of recombinations are 0.7 and 3.0 res-
2"5-
I'5
0.5
l/0
/20
200
28O
FIG. 4. Differential MWD curves of polystyrene obtained by polymerization in bulk at 70°. Concentration of PP of sebacie acid 0.05 base-mole/1.; degree of polymerization 9"4 (1) and 80.3% (2).
pectively, Consequently the narrowing of the MWD of the polymer as peroxide decomposition proceeds will be greatest with a P P of high degree of polycondensation, because under otherwise equal conditions this will give a greater average n u mb er of recombinations. Thus polymeric peroxides of dibasic organic acids when used as initiators of radical polymerization, permit production of polymers of higher molecular weight than when monofunctional initiators are used. Simultaneously with this increase in the degree of polymerization the MWD of the polymers becomes narrower. Translated by E. O. PHILLIeS REFERENCES 1. N. S. TSVETKOV and R. F. M.ARKOVSKAYA, Vysokomol. soyed. 6: 2051, 1964 (trans-
lated in Polymer Sci. U.S.S.R. 6: 11, 2273, 1964) 2. N. S. TSVETKOVand R. F. lYIARKOVSKAYA,Vysokomol. soyed. 7: 169, 1965 (Translated in Polymer Sei. U.S.S.R. 7: 1, 185, 1965) 3. N. S. TSVETKOV, R. F. MARKOVSKAYA and V. M. LUK'YANETS, European Polymer J., Suppl., 689, 1969
Synthesis and examination of organosilicon polycarbonates
2243
4. N. S. TSVETKOV and R. F. MARKOVSKAYA, Kinetika i kataliz 10: 57, 1969 5. N. S. TSVETKOV and R. F. MARKOVSKAYA, Khimiya i khim. tekhnologiya 11: 1936, 1968 6. G. V. SCHULZ, Z. phys. Chem. 43: 25, 1939 7. S. Ya. FRENKEL', Vvedenie v statisticheskuyu teoriyu polimerizatsii (Introduction to the Statistical Theory of Polymerization). p. 41, Izd. "Nauka", 1965
THE SYNTHESIS AND EXAMINATION OF ORGANOSILICON POLYCARBONATES* O. V. SMmNOVA, T. S. KLENOVA, G. D. KHATUNTSEV, V. D. SHELUDYAKOV, N. V. MmO~OVA a n d A. I. SEREBRE~IKOVA D. I. Mendeleyev Institute of Chemical Technology, Moscow (Received 4 March 1972)
The synthesis of polycarbonates containing silicon, from 1,1 -di (4-hydroxyphenyl) eyolohexane, phosgene and organosilicon bis-chloroformates (BCF), has been studied and the optimal reaction conditions have been found. I t was found that films cast from the copolymers so obtained are transparent, resistant to 40% NaOH solution and have good adhesion to glass. Copolymers from a mixture of the acid chlorides containing 30% of the BCF are best with respect to the above properties. B y synthesis of m i x e d p o l y c a r b o n a t e s containing organosilicon f r a g m e n t s o f the t y p e - - R - - S I - - O - - S i - - R - (where 1~ is a d i v a l e n t organic radical) w e
I I (CH3)~ (CH3)2 set ourselves t h e t a s k of p r e p a r i n g f r o m t h e m modified p o l y c a r b o n a t e m a t e r i a l s w i t h good adhesion to certain s u b s t r a t e s such as silicate glasses [1]. P o l y c a r b o n a t e s p r e p a r e d b y p a r t i a l r e p l a c e m e n t of p h o s g e n e b y d i m e t h y l dichlorosilane or b y organosiloxanes w i t h t e r m i n a l C1 a t o m s , which c o n t a i n h y d r o l y t i c a l l y v u l n e r a b l e S i - - O C linkages in t h e m a i n chain, are k n o w n [2, 6]. I n f o r m a t i o n on silicon containing p o l y c a r b o n a t e s (PC) in which t h e silicon a t o m s are linked to the c a r b o n a t e g r o u p i n g s b y h y d r o c a r b o n bridges is m o r e l i m i t e d
[17, s]. EXPERIMENTAL
Modified PC's containing disiloxane milts were prepared from 1,3-bis[o-(chloroformato) phenoxymethyl]-l,l,3,3-tetramethyldisiloxane (BCF-1) and 1,3-bis-[?-(o-ehloroformatophenyl)propyl]-l,l,3,3-tetramethyldisiloxane (BCF-2). BCF-1 was synthesized from 1,1* Vysokomol. soyed. A16: No. 9, 1940-1944, 1974.
N . S . TSVETKOV and R. F. MARKOVSKAYA REI:ER~NCE$
1. V. A. KABANOV, Sb. Kinetika i mekhanizm obrazovaniya prevrasheheniya m~kromolekul (Collected papers. The Kinetics and Mechanism of Formation and Reactions of Macromolecules). p. 25, Izd. "Nauka", 1968 2. V. F. GROMOV, A. MATVEEVA, A. D. ABKIN, P. M. KHOMIKOVSKII and E. I. MIROKI-IINA, Dokl. Akad. Nauk SSSR 179: 374, 1968 3. A. V. RYABOV, Yu. D. SEMCHIKOV and N. N. SLAVNITSKINA, Dokl. Akad. Nauk SSSR 154: 35, 1964 4. V. S. IVANOV, Radiatsionnaya polimerizatsya (Radiation Polymerization). Izd. "Khimiya", 1967 5. A. WEISSBERGER, E. PROSKAUER, J. RIDDICK and E. TOOPS, Organicheskie rastvoriteli (Organic Solvents). Foreign Literature Publishing House, 1958 (Russian translation) 6. U. N. MUSAYEV, A. KARIMOV, R. S. TILLAYEV and K. H. U. USMANOV, Uzb. khim. zh., No. 2, 47, 1972 7. Kh. U. USMA~OV, U. N. MUSAYEV, M. M. MIRKI-IIDOYATOV, A. KARIMOV and M. RAKHIMOVA, International Symposium on Macromolecular Chemistry, p. 861, 1972 9. Kh. S. BAGDASARYAN, Teoriya radikal'noi polimerizatsii (Theory of Radical Polymerization). Izd. "Nauka", 1966 10. N. N. LOGINOVA, Dissertation, 1969 l l . N. N. LOGINA and R. K. GAVURINA, Vysokomol. soyed. B l l : 355, 1969 (Not translated in Polymer Sei. U.S.S.R.)
POLYFUNCTIONAL INITIATORS OF RADICAL POLYMERIZATION AND THE MOLECULAR WEIGHT DISTRIBUTION OF POLYMERS* N. S. TSVETKOV a n d R . F . MARKOVSKAYA I v a n Franko State University, L'vov
(Reeived 28 February 1972) I n the synthesis of polymeric peroxides (PP) of dibasic acids by hetero-phase polycondensation of their diacid chlorides (DAC) with sodium peroxide, the nature of the solvent for the acid chloride has a substantial effect on the yield and molecular weight of the product. I t is shown that in order to increase the yield and molecular weight of a P P a non-polar liquid must be used, in which the P P is insoluble. The MWD of the P P ' s is typical of polymers obtained b y polycondensation, b u t the occurrence of side reactions (especially hydrolysis of the DAC) can alter the MWD curve. During the course of polymerization of styrene and other monomers in the presence of these peroxides the molecular weight of products increases continuously and the MWD becomes narrower. An explanation of these facts, which are associated with multiple recombination of propagating radicals, is given. * Vysokomol. soyed. AI6: No. 9, 1936-1939, 1974.
t)olyfunctional initiators of radical polymerization
2239
TttE polymerization of mono-olefinic compounds, initiated by polymeric peroxides (PP) of aliphatic dibasic acids, is characterized by increase in the molecular weight of the polymeric products as conversion of the monomer proceeds [1-3]. This property of polyfunctional initiators is of much interest for production of polymers of high molecular weight at high rates. The special value of PP's in cases where for one reason or another the monomer does not form polymers of high molecular weight with monofunctional initiators must be emphasized. The present paper discusses a study of the mechanism of formation of macromolecular chains in the presence of a polymeric peroxide as initiator and of the effect of this mechanism on the MWD of the polymer. The polyfunctional initiators used were PP's of various aliphatic acids, the characteristics of which are given in reference [4]. The monomer was styrene. ]~olymeric peroxides of dibasic earboxylic acids were prepared from the corresponding acid chlorides and sodium peroxide, b y heterophase polyeondensation. The acid obJorides were first dissolved in a non-polar liquid and the sodium peroxide in an aqueous sohition of sodium acetate. The conditions of preparation of the PP's have a marked effect on the yield of the product and on its degree of polycondensation. There is no information in the literature that would throw light on the nature of this effect. The reaction between sodium peroxide and an acid chloride is highly exothermic, proceeds at a high rate and is practically completed in a few minutes. To reduce the probability of occurrence of side reactions the preparation was carried out at 0-4 ° . Preliminary investigations showed (Table) that the yield and molecular weight of the P P are most strongly dependent on the solubility of the
'~~'-'~#3-
¢gtj O.2 /0
I
I
20
30
I
z/Op
FIo. I. MoleoLdar weight distribution of the po|yperoxide of pimelio acid. Average
degree Of polyeondensation 9.6; 1, / ' - - e x p e r i m e n t a l curves, 2--theoretical curve. latter in the organic phase. It, is known that the affinity between PP's and non-polar substances varies within wide limits and is dependent on the nature of the hydrocarbon radical between the peroxide groups. In the case of PP's of higher aliphatie acids (from pimelic to 1,16-hexadecadicarboxylie) the yield of the product decreases steadily in the following series of solvents: C C 1 4 > e t h e r > n - h e x a n e > o h l o r o b e n z e n e > b e n z e n e > e h l o r o f o r m . This sequence correlates w i t h the solubility of the PP's in these substances, insoluble PP's (of suoeinic, glutaric, adipic and aromatic dicarboxylic acids) are formed in the same yield in all the reaction mixtures examined. The MWD of the peroxides was studied by precipitation chromatography in a column w i t h a linear temperature gradient of 0.7 deg/cm and successive increase in the thermodynamic quality of the solvent (methanol-benzene). The temperature in the heated zone was
2240
N. S. TSV~TKOV and R. F. MARKOVSKAYA
30¢ and the lower part of the column was water cooled to 10°. For construction of a true picture of the MWD the peroxide samples were divided into a fairly large number of fractions (20-50), varying in their average degree of polycondensation, which were then analysed for the active oxygen content. Figure 1 shows integral and differential curves of the MWD of one sample of the PP from i~imelic acid, prepared in the presence of ether as solvent for the acid chloride. The shape of the differential curve in Fig. 1 is typical of polymers obtained by polyeondensation. The comparatively small deviation of the experimental curve from the curve calculated according to the equation Wn=np2(1 _p),,-1 (n is the number of peroxide linkages in the PP molecule and p the degree of degradation) is evidently due to the heterogeneity of the reaction system. The formation of a polyperoxide as a new phase as it is synthesized results in a narrow MWD. Inhomogeneity of a PP with respect to molecular weight can be increased by side reactions, especially hydrolysis of the acid chloride. E F F E C T O~' THE SOLVENT FOR THE ACID CHLORIDE ON THE Y I E L D OF A POLYMERIC P E R O X I D E
(Reaction temperature -- 0°, time -- 15 min) Acid from which peroxide is derived Azelaie
Adipic
Solvent
CC14 Ether n-Hexane Cyclohexane Chlorobenzerie Benzene Chloroform Chlorobenzene CCI~ Chloroform
Solubility of the peroxide in the organic phase
Yield of peroxide, %
Active oxygen in peroxide, %
i i i p.s
62"7 53"3 55'4 40'5
93"5 93"6 93"4 95"0
19'0 12"6 11"2 45"4 44"8 46"3
86"9 84"1 83"5 95"0 96"2 94"0
i--insoluble, s-soluble, p.s.-partially soluble. The n a t u r e of t h e m o n o m e r unit, the average degree of p o l y c o n d e n s a t i o n a n d t h e M W D of the polymeric p e r o x i d e s used as p o l y m e r i z a t i o n initiators do n o t show a n y m a r k e d effect on the conversion of styrene in p o l y m e r i z a t i o n in bulk (Fig. 2). A t the same time the molecular weight of the p o l y m e r is dir e c t l y p r o p o r t i o n a l to the n u m b e r of peroxide groups in the multffunctional initiator [3, 5]. I n f r a r e d s p e c t r o s c o p y a n d o t h e r m e t h o d s show t h a t f r a g m e n t s o f the P P enter the composition o f the p o l y m e r molecule. The relative c o n t e n t of peroxidic groupings in the macromoleeular p r o d u c t s correlates with the original c o n c e n t r a t i o n of the P P t a k e n as initiator (Fig. 3). D u r i n g the course of :polymerization the free P P decomposes r a p i d l y a n d s u b s e q u e n t initiation occurs b y b r e a k d o w n of the 0 - - O b o n d in f r a g m e n t s o f the p o l y f u n c t i o n a l initiator forming p a r t of new p o l y m e r molecules. This produces conditions in which the n u m b e r of p o l y m e r molecules in the reaction m i x t u r e remains practically unc h a n g e d (assuming, of course, t h a t chain transfer does n o t occur).
Polyfunctional initiators of radical polymerization
2241
I t is interesting to note that the average proportion of carboxylate groups in the polystyrene molecules falls progressively as the original concentration of P P in the reaction mixture is decreased. This indicates that the concentration of P P in the solution affects the primary thermal degradation of the peroxide linkages in it, which is exhibited as change in the degree of decarboxylation. Figure 4 shows MWD curves of polystyrene obtained at various degrees of conversion. The MWD was investigated by precipitative chromatography in a column with a linear temperature gradient of 1.3 deg/cm. The solvent and precilO0
D
2O
J/ I
3
_ IL/\
0"8
a# I
I
g T/me, hr FIo. 2
I
I
15
18
17
Ib"
p,, IlT-z c m -;r
FIG. 3
FIG. 2. Time dependence of the degree of polymerization of styrene: a - - 70 °, initiator concentration 0.0276 base-mole/1.: 1 - - P P of suberic, 2--azelaic, 3--1,16-hexadecadicarboxylic acid; b - - 8 0 °, concentration of P P of pimelie acid 0.50 g/100 ml; degree of polycondensation of the peroxide: 4-- 13.1; 5-- 27.5, 6--44.6. FIG. 3. I n f r a r e d spectra of polystyrene solutions in CC14. Polystyrene prepared in the presence of the P P of azelaic acid at initiator concentrations of: 1--1.00, 2--0.50, 3--0'10, 4--0.01 base-mole/1.
pitant for the polystyrene were benzene and methanol respectively. The rate of addition of solvent was 50 ml/hr. The results show that as the extent of thermal degradation of the P P in the polymerization system increases the average molecular weights increase and the MWD narrows. Determination of the degree of inhomogeneity of the polymer by the Sehulz method, for two polystyrene samples separated at degrees of conversion of 9.4 and 80.3~o, gives numerical values of 0.60 and 0.25 respectively. I t is well known that these effects (increase in molecular weight with simultaneous narrowing of the MWD during the course of polymerization) are found in polymerization by the "living" polymer mechanism. In the presence of a polyfunctional initiator the polystyrene molecules are formed by multistage propagation of the polymer chain [2]. From the statistical
2242
N . S. TSVETKOVand R. F. MARKOVSKAYA
point of view this can be equated to multiple recombination of growing radicals. As a result of this the MWD of the polymer at constant relative rates of chain propagation and termination will be similar to a Schulz distribution [6]. The ratio M w / M n can be interpreted in terms of the "average number of recombinations" resulting in formation of " d e a d " chains [7]. For.the polystyrene samples mentioned above the average numbers of recombinations are 0.7 and 3.0 res-
2"5-
I'5
0.5
l/0
/20
200
28O
FIG. 4. Differential MWD curves of polystyrene obtained by polymerization in bulk at 70°. Concentration of PP of sebacie acid 0.05 base-mole/1.; degree of polymerization 9"4 (1) and 80.3% (2).
pectively, Consequently the narrowing of the MWD of the polymer as peroxide decomposition proceeds will be greatest with a P P of high degree of polycondensation, because under otherwise equal conditions this will give a greater average n u mb er of recombinations. Thus polymeric peroxides of dibasic organic acids when used as initiators of radical polymerization, permit production of polymers of higher molecular weight than when monofunctional initiators are used. Simultaneously with this increase in the degree of polymerization the MWD of the polymers becomes narrower. Translated by E. O. PHILLIeS REFERENCES 1. N. S. TSVETKOV and R. F. M.ARKOVSKAYA, Vysokomol. soyed. 6: 2051, 1964 (trans-
lated in Polymer Sci. U.S.S.R. 6: 11, 2273, 1964) 2. N. S. TSVETKOVand R. F. lYIARKOVSKAYA,Vysokomol. soyed. 7: 169, 1965 (Translated in Polymer Sei. U.S.S.R. 7: 1, 185, 1965) 3. N. S. TSVETKOV, R. F. MARKOVSKAYA and V. M. LUK'YANETS, European Polymer J., Suppl., 689, 1969
Synthesis and examination of organosilicon polycarbonates
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4. N. S. TSVETKOV and R. F. MARKOVSKAYA, Kinetika i kataliz 10: 57, 1969 5. N. S. TSVETKOV and R. F. MARKOVSKAYA, Khimiya i khim. tekhnologiya 11: 1936, 1968 6. G. V. SCHULZ, Z. phys. Chem. 43: 25, 1939 7. S. Ya. FRENKEL', Vvedenie v statisticheskuyu teoriyu polimerizatsii (Introduction to the Statistical Theory of Polymerization). p. 41, Izd. "Nauka", 1965
THE SYNTHESIS AND EXAMINATION OF ORGANOSILICON POLYCARBONATES* O. V. SMmNOVA, T. S. KLENOVA, G. D. KHATUNTSEV, V. D. SHELUDYAKOV, N. V. MmO~OVA a n d A. I. SEREBRE~IKOVA D. I. Mendeleyev Institute of Chemical Technology, Moscow (Received 4 March 1972)
The synthesis of polycarbonates containing silicon, from 1,1 -di (4-hydroxyphenyl) eyolohexane, phosgene and organosilicon bis-chloroformates (BCF), has been studied and the optimal reaction conditions have been found. I t was found that films cast from the copolymers so obtained are transparent, resistant to 40% NaOH solution and have good adhesion to glass. Copolymers from a mixture of the acid chlorides containing 30% of the BCF are best with respect to the above properties. B y synthesis of m i x e d p o l y c a r b o n a t e s containing organosilicon f r a g m e n t s o f the t y p e - - R - - S I - - O - - S i - - R - (where 1~ is a d i v a l e n t organic radical) w e
I I (CH3)~ (CH3)2 set ourselves t h e t a s k of p r e p a r i n g f r o m t h e m modified p o l y c a r b o n a t e m a t e r i a l s w i t h good adhesion to certain s u b s t r a t e s such as silicate glasses [1]. P o l y c a r b o n a t e s p r e p a r e d b y p a r t i a l r e p l a c e m e n t of p h o s g e n e b y d i m e t h y l dichlorosilane or b y organosiloxanes w i t h t e r m i n a l C1 a t o m s , which c o n t a i n h y d r o l y t i c a l l y v u l n e r a b l e S i - - O C linkages in t h e m a i n chain, are k n o w n [2, 6]. I n f o r m a t i o n on silicon containing p o l y c a r b o n a t e s (PC) in which t h e silicon a t o m s are linked to the c a r b o n a t e g r o u p i n g s b y h y d r o c a r b o n bridges is m o r e l i m i t e d
[17, s]. EXPERIMENTAL
Modified PC's containing disiloxane milts were prepared from 1,3-bis[o-(chloroformato) phenoxymethyl]-l,l,3,3-tetramethyldisiloxane (BCF-1) and 1,3-bis-[?-(o-ehloroformatophenyl)propyl]-l,l,3,3-tetramethyldisiloxane (BCF-2). BCF-1 was synthesized from 1,1* Vysokomol. soyed. A16: No. 9, 1940-1944, 1974.