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Molecular mobility and the kinetics of radical polymerization
MOLECULAR MOBILITY AND THE KINETICS OF RADICAL POLYMERIZATION * V. V. KOCH]~RVII~SKII,Z. A. KxaAP~Tr~a~, V. P. ROSHCHUPKrI~,B. 1~. S~III~OV and G. V. KoRon~,v Division of the Chemical Physics Institute, A c a d e m y of Sciences, U.S.S.R.
(Received 24 June 1974) A "dlelecometer-calorimeter" apparatus has been constructed t h a t enables the heat evolution, dielectric permeability, 8', and the conductivity, ~, of a m o n o m e r - p o l y m e r system to be recorded simultaneously during polymerization. The radical polymerization of a number of acrylates, methacrylates and dimethacrylate oligomers has been studied. A correlation has been established between the specific molecular mobility in the monomer-polymer system, a t polymerization to various extents, with the kinetic characteristics of the process.
THv. processes in polymer synthesis do not reduce to the chemical transformation of the monomer molecules to form maeromolecules, but are also accompanied by the formation of the definite supermolecular structure of the polymer. The structural and physical transformations in the monomer-polymer system determine many features of the kinetics of radical polymerization. The effect of structural formation on the kinetics is thus exerted, to a considerable extent, through a change in molecular mobility. In connection with this, the study of the interrelation between physical and chemical kinetics is a present task in the chemical physics of polymers. We have previously [1] suggested a method of studying this interrelation, based on the simultaneous measurement of the dielectric permeability, ~', the conductivity, a, and the heat evolution in the monomer-polymer system during polymerization. It has been established [2-5] with a number of processes in the formation of linear and network polymers as examples, that this method makes it possible to do the following: 1) To assess, from the change in e', both the change in the rotational mobility of the monomer and the polymeric chain molecules and also the transition of the monomer-polymer system from the condition of a molecular solution into the condition of a microheterogeneous dispersion of polymer particles in the monomer; 2) To obtain information about the translational diffusion for the monomer and polymer molecules from the behaviour of a, because of the common features between the mechanisms of electrical conductivity and * Vysokomol. soyed. A17: No. 11, 2425-2433, 1975. 2790
Kinetics of radical polymerization
2791
diffusion; 3) To establish unambiguously the correlation between the change in these forms of molecular movement during the process and the rate of polymerization. The present work is devoted to a generalization of data both new and obtained previously by the "dielecometer-calorimeter" method, in studying of the polymerization of monomers of the acrylic and methacrylic series and dimethacrylate oligomers. The selection of the experimental materials was dictated by the desire to characterize the connection between molecular movement and the kinetics of radical polymerization as a function of the molecular structure of the linear polymers formed (the presence or absence of ~-methyl groups and a variation in the length of the side substituent are known to have a substantial effect on the flexibility of the main chain), and as a function of the formation of any spatial network of chemical bonds and the properties of the block polymers being formed. The considerable differences in the glass transition temperatures, T~, of the polymers formed enabled the polymer-monomer systems (with selected conditions of temperature during polymerization) to be studied both in the highly elastic and also in the glassy conditions, and enabled the effect of the transition of the polymerizate into the glassy condition on the features of the polymerization reaction to be clarified. 2 1
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I I I I I I I I
L
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b FIo. 1. Block diagram of installation for the simultaneous recording of the polymerization kinetics and the dielectric properties of the monomer-polymer system: a represents the cell; 1 - high voltage electrode; 2--measuring electrode; 3--thermocouple system; 4--polymerizate; 5--insulator; b is the dieleeometer; 6--E8-2 bridge; 7--EG-4 generator; 8 - - E L U R - 3 nul indicator; c is the calorimeter; 9--F-116 DC amplifier; 10--EPP-09.
The simultaneous study of the polymerization kinetics and the dielectric properties was made with equipment combining both a calorimeter and a dieleeometer (Fig. 1). The polymerization kinetics were recorded from the heat evolution in a type UP-2 calorimeter [1]. The dielectric measurements were made with an assembly of stemdard pieces of apparatus.
V . V . KOOltERVINSKII et al.
2792
:For t h e dielectric m e a s u r e m e n t s , t h e s t a n d a r d cell of t h e c a l o r i m e t e r was c o n v e r t e d i n t o a c o n d e n s e r b y i n s t a l l i n g a n i n s u l a t i n g r i n g m a d e of teflon (Fig. 1, 5). I n o r d e r to incrcaso t h o t h e r m M i n s u l a t i o n of t h e r e a c t i o n cell, t h e l a t t e r was c o n n e c t e d w i t h t h e b r i d g e b y s m a l l diam e t e r c o n d u c t o r s (0.2 r a m ) . M e a s u r e m e n t s were carried o u t a t 3 fixed frequencies, n a m e l y , 4 × l 0 ~, l03 a n d 5 × l 0 '~ Hz. T h e dielectric p e r m e a b i l i t y e' ~ a s c a l c u l a t e d f r o m t h e e q u a t i o n : ~" = C 1 - - C e / C 0 - - C e
(
1)
w h e r e C~ is t h e c a p a c i t y of t h e eond(,l~s(~r w i t h the, liquid u n d e r i n v e s t i g a t i o n , p F ; Co is t h e c a p a c i t y of t h e e m p t y c o n d e n s e r ; C e is t h e leakage, c a p a c i t y , c o n s i s t i n g of t h e c a p a c i t y of t h e i n s u l a t o r a n d t h e eapaei~ y of t h e air spaco o u t s i d e t h e v o l u m e of t h e liquid; C~ was d e t e r m i n e d f r o m eqn. (1) for s t a n d a r d liquids (bonzcne, CC14). T h e tangent, of t h e dieh, etrie loss angle, t.an 6, was c a l c u l a t e d f r o m t h e e q u a t i o n : t a n 5 - - a/~o (C~ --Co),
(2)
w h e r e a is c o n d u c t i v i t y , o h m -~ a n d w is t h e a n g u l a r f r e q u e n c y , see -~.
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:Fro. 2. D e p e n d e n c e of." 1, 2 a n d 3, e'; 1', 2" a n d 3', t a n 6 a n d 4, thc~ e x t o n t of p o l y m e r i z a t i o n o n t h e t i m e of p o l y m e r i z a t i o n of ]~IMA (50°C, 1 o{, B P ) . 1 a n d 1', 4 × 102 Hz; 2 a n d 2", 10 a H z a n d 3 a n d 3', 5 × 10 a Hz. T h e a b s o l u t e e r r o r in m e a s u r e m e n t s of t h e e x t e n t of c o n v e r s i o n , C, was a p p r o x i m a t e l y 3 /o/o , i n e', 0.4 a n d in t a n 6, 0.001; t h e r e l a t i v e e r r o r in t h e m e a s u r e m e n t s of e' wt~s ~0.5°~,. T h e m o n o m e r s were purified b y t h e s t a n d a r d m e t h o d s u s i n g p r c p o l y m e r i z a t i o n , r.rh~, olig o m e r s were purified in s o r p t i o n c o l u m n s for p r e l i m i n a r y a m l fine p u r i f i e a t i o n b y t h e m e t h o d g i v e n in [6]. T h e p u r i t y of t h e p r o d u c t s (the a b s e n c e of i n h i b i t i n g i m p u r i t i e s ) was monitorc d k i n e t i e a l l y [6]. B e n z o y l p e r o x i d e (BP) or d i e y e l o h e x y l p e r o x y d i e a r b o n a t e (CPC) was u s e d as t h e i n i t i a t o r of p o l y m e r i z a t i o n , d e p e n d i n g o n t h e t e m p e r a t u r e of t h e e x p e r i m e n t . ,The exp e r i m e n t s were c a r r i e d o u t i n a n a t m o s p h e r e of a r g o n .
2793
Kinetics of radical polymerization
e', tan 5 and the degree of conversion (C) were recorded as functions of the polymerization time (Fig. 2). The results were analysed from the way in which e', tan 5 and w/[M] (w being the polymerization rate and [M] being the monomer concentration) depended on the degree of conversion. L e t us s t a r t the diseu ssion of the results o b t a i n e d with the d a t a for t h e p o l y m e r i zatic, n of MMA. I t m a y be seen front Fig. 3a, a n d c, t h a t all t h r e e quantities m e a s ured (c', ta~ 6 a n d w/[M]) are c h a r a c t e r i z e d b y t h r e e regions of different b e h a v i o u r durL,~!., the process. Region I is c h a r a c t e r i z e d b y a slight fall in c' a n d a s h a r p reduel.ion in tan 5. An a n o m a l o u s increase in e', r e l a t e d to the a u t o a e e e l e r a t i o n stage i~ the re~etion, ~md a slight, decrease in t a n 6 are o b s e r v e d in region I f . Finally, in region I I I , we n o t e a slight increase in tan 6 and a m a r k e d fall in c', which is a c c o m p a n i e d b y a slowi~g down of the reaction. Region I. I t is k n o w n f r o m the t h e o r y of dielectrics [7] t h a t tan d=
,~:~i c0 -c~:, l ~ (~,)r)::
-
(3) '
where ~, a n d c:~ are the static a n d high f r e q u e n c y dielectric permeabilibies; Yv is the specific ¥ o l u m e c o n d l ' c l i v i t y , o h m -~.cm-~; z is the r e l a x a t i o n time, sec-~; a n d (.,) is t h e fl'ef ] 0 ~0_.10-s see. U n d e r these eou(liti(,~s at t h e field freqneneies selected, (,)r<:!, and t a n 6 is d e t e r m i n e d b y t h e losses f r o m direct e - n d u e t i v i t y . W i t h this t a k e n into account, t h e analysis :for a fixed de?.re<~ <~f c,l!versio~ i~E<;i(ates {bat the direct c o n d u c t i v i t y looses are predom;l~ant riaiil up to C==4(!-70~.~, (depem]i~g on the n a t u r e of t h e m o n o m e r a n d t h e ~t e m l ) e r a t u r ~ of the e x p e r i m e n t ) . This m e a n s t h a t the s h a r p decrease in t a n b in region I is c o n n e c t e d with a decrease in the v o l u m e c o n d u c t i v i t y , ' v = ~n~q#~t (where .~. a n d qi are the c o n c e n t r a t i o n of the i t h carrier a n d its charge r e s p e c t i v e l y a n d gz is the m~biliCy of the ith carrier). On the basis of the existing d a t a , t h e eha:;~_,e in ?, m a y be .principally c o n n e c t e d w i t h a change in carrier m o b i l i t y * . A.-c(;r(liny t,~, ~h.,: E i n s t e i n - N e r n s t equation, D--/(/..:T/q the decrease in It mus~ be e ~ m e c t e d with a decrease in the diffusion coefficient, D, of the carriers during p o l y m e r i z a t i o n . I t m a y be e(msidercd tl:al; the diffusion coefficient for m o n o m e r mc.l(~(:,des v a r y in m u c h t h e s a m e v:av as the m,)bility of t h e carriers, since tim latter ()b-io~sly differ little f r o m the m, m o m e r molecules w i t h respect to dimensions a n d affinity tov. ards the p o l y m e r . I: m ~ v be seen from Fig. 3 t h a t a n increase in th~.~ d(,,.:ree (~f e(,!wersion t(} 3 0 % or a b o v e leads to a reduction in t a n (~, a n d consequel~liy in D as well, t h a i is not greater t h a n a n order of m a g n i t u d e . At t h e s a m e time, the b-~erease in the m a c r ,~eopie vise(~sity ( f the p o l y m e r i z a t e , which is d e t e r m i n e d b y the coefficie~t of txanslationa! diffusion of the maeromoleeules, * A similar conclusion has also been reached in an investigation of the electrical eonductivity of polymer solutions [81.
2794
V . V . KOCHERVINSKII et al.
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FzG. 3. Dependence of: 1, 2 and 3, e'; 1', 2" and 3', tan ~; 4, w/[M] and 5, the radius of the polymerization particles R on the extent of polymerization, C, for the following: a and b --MMA; c--BMA; d--MA; e - - B A ; f - - T G M - 3 ; g--MGPh-9; h - - M B under various conditions: a--30°C, 1% CPC, f--108 Hz; b--50°C, I~o BP; c--50°C, 1.72% BP; d, e--30°C, 0.3% CPC; b, c and d--frequencies as follows: 1, 1 ' - - 4 X 103 Hz; 2, 2'--103 Hz; 3, 3 ' - - 5 X 103 Hz;f--70°C, 0"035~o BP, f = 103 I-Iz; g--50°C, 0-023~o CPC, 103 Hz; h--70°C, 0-012~o BP, 10a Hz.
Kinetics of radical polymerization
2795
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amounts to several orders of magnitude at the same polymer concentrations. Conductivity measurements clearly give information about the change in microviscosity during polymerization, whith is a decisive factor in the transport of monomer molecules to the macroradical. Since the reduction in the coefficient of translational diffusion in region I is not accompanied by any appreciable change
2796
V.V.
KOCHERVINSKII et
at.
in the reaction rate, it may be concluded that chain propagation is not diffusion contro]led at this stage. In order to analyse the dielectric permeability during polymerizati(m, we shall take advantage of the equation [7]: 09
e'=e~ + (Co--Zo~) ~ f(r)dr/1 + (o)r) 2,
(4)
o
where f (r) is the distribution function of rela×ati(;n times. For :o~ <~l e'--c(), that is, the dielectric permeability in region I characterizes the static dielectric permeability. With the condition that the permeability is additive ibr the polymer-monomer system in the case of a nlolecl~iar solution, it may be represented in the form: , 2eo ( c ~ + 2 \ 2 ~o-eo~±~-:-| ., / Z%-i-e~\ o /
=~~-, ( ~--z)/fl,': 4 ~ 5 .: o i. L'~;/~:,,I -
3kT
] '
(5)
where N o is the number of dipoles in unit volume, g~ and x are the effective dipole moment of the monomer and its fraction in solution respectively, /q, and (l--x) are the effective dipole moment per monomer unit in the polymeric chain and the proportion of the polymer in solution respect.ively. The value of #p for the polymer is known to be always less than /,~f !br the monomer because of enhanced intra- and intermolecular inters~:.tio~Ls [9]. An increase in the proportion of the component with the lower value of g, which occurs during polymerization, must, according to eqn. (5), lead to a reduction in e0 (that is, d), as is observed in region I. An anomalous increase in e' is, however, observed in region II. The appearance of the positive increment in the dielectric permeability has been explained [2-5] by the formation of microheterogeneity in the polymerizate and by the mechanism of Maxwell-Wagner type polarization connected with this. Experimental and theoretical investigations of recent years have, in fact, uncovered the phenomenon of a gigantic low-frequency dispersion in colloidal suspensions of polymeric particles, which may be explained within the framework of the Maxwell-Wagner heterogeneous dielectric model with polarization of a double electric l~yer [10]. Another confirmation of the fact that the polymerizate in region II changes from the molecular solution condition into the condition of a dispersion of polymer particles in the monomer, has been obtained by investigating the turbidity spectra of the polymerizate [11]. It may be seen from Fig. 3b, which shows the dependence of the effective particle radius on the degree of conversion [11], that the region of increasing e' and of increasing particle size belong to the auto-acceleration stage of polymerization. This points to the fact that immobilization of macroradicals in the polymer particles and the reduction in their segmental mobility connected with this lead to a decrease in the constant for termination and to an increase in the polymerization rate. A sharp decrease in dielectric permeability, which is accompanied by a slowing
Kinetics of radical polymerization
2797
down in the reaction, is observed in region III. Since the dielectric permeability is very sensitive to micro-Brownian segmental lnovement, this fact is readily explained b y "freezing-out" of cooperative forms of movement in the frequency range investigated. This indicates that, in the later stages, chain propagation passes into the diffusion-controlled region. In fact, because of the increase in the proportion of structured polymer in the later stages, the transport of monomer units to the reaction sites will depend essentially on the details of segmental movement, since it is precisely through such movements within the polymeric matrix that holes (vacancies) are created, and it is b y these that transfer processes are accomplished [12]. Features of the behaviour of the dielectric properties of polymerizate as a function of the polymeric chain structure. Data from the polymerization of butylmethacrylate (BMA) indicate (Fig. 3c) that here, just as in the case of MMA, the region of uniform decrease in e' belongs to the region where the reaction rate increases slightly. However, with auto-acceleration (less pronounced), the anomalous increase in ~' is not observed, although the deviation of the experimental curves for e' (C) from that calculated from the Debye theory for a molecular solution also points in this case to micro-heterogeneity in the monomer-polymer system [5]. The increase in the volume of the substituent in the ester group on going from MMA to BMA clearly leads to a weakening of inter-chain interactions and impedes macromolecular aggregation. In this connection, micro-heterogeneity should be less pronounced in the BMA polymerizate than in MMA, and this should lead to a smoothing, out in the effects of additional polarization. On the other hand, the absence of an a-methyl group in the PMA chain should lead to an intensification of inter-chain interactions and to the effect of an increase in additional polarization being more clearly expressed than in the case of PMMA. In fact, an increase in dielectric permeability and auto-acceleration of the process are observed even in the earliest stages during the polymerization of methylacrylate (NA) (Fig. 3d). Chemical crosslinking through chain transfer at e-hydrogen may, in this case, make an additional contribution to the aggregation process (one crosslink for each 10a-104 monomer links) [13]. A certain screening of the inter-chain interaction, involving the side group, on going to BA reduces the additional polarization effect (Fig. 3e), although the regular features of the auto-acceleration of the reaction are the same as in the case of MA. The greater flexibility of the polymer chains of acrylic polymers as compared with polymethaerylates is clearly the reason why, in both acrylates, the occurrence of auto-deceleration of the reaction (a maximum rate on the curve for w/[M]) is found at the beginning of the freezing-out of segmental forms of movement at frequencies above approximately 10s Hz. This may be clearly seen from the data for the polymerization of MA (Fig. 3d) where the maximum in the reaction rate
2798
V. ¥. KOC~ERVI~SXIIet al.
ment at the frequency range investigated, since even at limiting degrees of conversion no marked decrease in the dielectric permeability is observed, which would characterize the freezing-out of segmental movement although the reaction occurs, as in the other cases, with auto-deceleration. The process of freezing out of segmental movement in the monomer-polymer system obeys a common relaxation law: the higher the frequency of the superimposed field, the lower the degree of conversion at which the decrease in s' is found. Thus the reaction rate in the auto-deceleration stage is insensitive to the transition of the system into the glassy condition where all forms of segmental movement become frozen. On the contrary, the start of auto-deceleration of the reaction is connected with the freezing out of movements of a specific (critical) frequency, which is different for the various polymers (Fig. 3b-e). In the case of P]~IMA, these are frequencies of the order of 10 a Hz: they are rather higher for PBMA and must be even greater for polyacrylates. An increase in the width of the frequency range investigated would have enabled the critical frequencies to be determined in these cases with greater accuracy. I t should be noted that the increase in the critical frequency of the processes in the series investigated correlates with the glass temperature of the block polymer formed: the lower Tg, the higher the critical frequency. Polymer Tg, °C PMA 8 Polybutylacrylate (PBA) --56 PMM.A 110 PBMA 24 The structural features that determine T~ clearly determine the relaxation times for segmental movement in the ~monomer-polymer system as well. The relaxation time for segmental movements of macroradicals determines the probability of their recombination, that is, the constant for termination, k t. In connection with this, attention should be given to the good correlation between the flexibility of the polymer chains and the rate of anihilation of "trapped" macroradicals. According to the data of Melwille [14], the average lifetime of trapped radicals in PMMA under comparable conditions is more than 5 times greater than the corresponding time in PBA. The rate of annihilation of "imprisoned" macroradicals in PMA is reported to be greater than that in PMMA [15]. It may therefore be concluded that the progressive reduction in chain flexibility in the series of linear polymers investigated on going from P B A to PMMA will be accompalfied b y a regular decrease in k t. The reduction, in the same series, of the critical fiequencies for molecular movement confirms this conclusion. Network polymers. The polymers formed from dimethacrylate-butadiol (MB), dimethacrylate-triethylene glycol (TGM-3) and dimethacrylate-bis-triethylene glycol phthalate (MGPh-9) are characterized b y broad region in which the changeover to the glassy state occurs. The common regular feature which char-
Kinetics of radical polylnerization
2799
racterizes the polymerization of oligo-ester-acrylates is as follows: the beginning of auto-deceleration of the reaction pertains to a degree of conversion when the freezing out of segmental forms of movement has already begun, as judged from the reduction in e' (Fig. 3f-h). This means, according to [3], that the rate of polymerization of oligo-ester-acrylates in the later stages is limited by the low frequency forms themselves of conformational regroupings. A characteristic feature of all the three dimensional polymers investigated is the very wide region of dispersion of ~', characterizing the freezing out of segmental mobility, which sets in in polymers with a network structure when the distance between crosslinks becomes less than the size of the kinetic segment. The broad region of dispersion in ~' is reported [3] to be caused by structural nonuniformity in the oligo-ester-acrylates and is evidence that regions with an enhanced density of crosslinking exist in them even in the early stages of conversion, the distance between the chemical points of attachment being less in these regions than the length of the kinetic segment. It is precisely these regions which are responsible for the reduction in the dielectric permeability in the early stages of the polymerization process. On the other hand, the reduction in ~' that continues in the later stages close to the limiting conversion means that, even at such large conversions, there still exist regions with sparse crosslinking where segmental mobility may be realized. This behaviour of the reaction system is best described within the framework of the following model: 1. The primary linear macromolecules formed, which contain one unreacted double bond for each link (potential sites for branching and crosslinking), aggregate and the aggregates themselves become stabilized by branching and crosslinking reactions, becoming converted into densely crosslinked particles of microgel. Thus even in the earliest stages of conversion, network macromoleeules appear with chain links between the points of attachment less than the kinetic segment. 2. As the densely crosslinked micro-particles (of microgel) accumulate in the reaction system, the density of the network in the spaces between the micro-particles remains very much less (because of local auto-acceleration, of the gel effect type, in the particles, steric hindrances at the particle boundary, the development of microsyneresis within the particles, etc.). In this way, even in the later stages of conversion when the average distance between crosslinks becomes less t h a n the kinetic segment, network macromolecules still remain having a distance between crosslinks greater t h a n the segment. The authors wish to express their thanks to M. P. Berezin for participating in the experimental part of the work. Translated by G. F. MODT.E~ REFERENCES 1. Z. A. KARAPETYAN, V. V. KOCHERVINSKII~ V. P. ROSHCHUPK1N, B. P. SMIRNOV
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2800
M . T . BRYK et al.
2. V. P. ROSHCHUPKIN, V. V. KOCHERVINSKII, Z. A. KARAPETYAN and G. V. KOROLEV, Vysokomol. soyed. B13: 317, 1971 (Not translated in Polymer Sci. U.S.S.I~.) 3. V. P. ROSHCHUPKIN, V. V. KOCHERVINSKII, O. G. SEL'SKAYA and G. V. KOROLEV, Vysokomol. soyed. B13: 497, 1971 (Not translated in Polymer Sci. U.S.S.R.) 4. V. P. ROSHCHUPKIN and G. V. KOROLEV, Doklad na 18-i konferentsii po vysokomolekulyarnym soyedineniyam (Contribution to the 18th Conference on Polymers). Kazan', 1973 5. V. V. KOCHERVINSKII and Yu. V. ZELENEV, Vysokomol. soyed. A17: 2231, 1975 (Translated in Polymer Sei. U.S.S.R. 14: 10, 1975) 6. G. V. KOROLEV, Dissertation, 1965 7. N. P. BOGORODITSKII, Yu. M. VOLOKOBINSKII, A. A. BOROB'YEV and B. M. TAREYEV, Teoriya dielektrikov (Theory of Di¢~lectries). Izd. "Energiya", 1965 8. V. P. SHUVAYEV, Dissertation, 1968 9. A. A. TAGER, Fiziko-khimiya polimerov (Physical Chemistry of Polymers). Izd. "Khimiya", 1968 10. V. N. SHILOV and S. S. DUKHIN, Kolloidn. zh. 32: 293, 1970; T. L. CHELIDZE and V. N. SHILOV, Kolloidn. zh. 35: 105, 1973 11. B. V. OZERKOVSKII, G. M. CHPLAKHYAN and V. P. ROSHCHUPKIN, Uch. zap. Yerevanskogo gos. un-ta. No. 3, 82. 1974 12. H. L. FRISH, J. Polym(~r Sci. B3: 13, 1965 13. C. BAMFORD, O. BARB, A. ,JENKINS and R. ONYON, Kinetika radikal'noi polimerizatsii vinilovykh soye(lineHii (Kinetics of the ]~adical Polymerization of Vinyl Compounds). Izd. inostr, lit.. 1961 (14ussim~ translation) 14. H. W. MELWILLE, Z. Elektrochem. 60: 276, 1956 15. S, Ye. BRESLER, E. N. KAZBEKOV and Ye. M. SAMINSKII, Vysokomolek. soyed. 1: 136, 1959 (Translated in Polymer Sci. U.S.S.R. h i, 55, 1960)
THERMAL POLYCONDENSATION OF DIPHENYLSILANEDIOL CONTAINING DISPERSED OXIDES OF TITANIUM, IRON, COBALT OR COPPER* M. T. BRYK, I. A. VARAVKOand O. D. KURILE~KO Institute for Colloidal and Water Chemistry, Ukr. S.S.R. Academy of Sciences
(Received 29 August 1974) I R spectroscopy arid thermal analysis have been used to investigate the adsorption interaction between diphenylsilanediols and dispersed oxides of the 3d transition metals. The thermal polycondensation of diphenylsilanediol containing dispersed oxides has been investigated and it has been shown that the mechanism of polycondensation of the monomer depends on the characteristics of the adsorption interaction between it and the oxide surface. The struetur(., molecular weights and degree of grafting of the polymer formed in the presence of the specified oxides have been studied. * Vysokomol. soyed. A17: :No. 11, 2434-2440, 1975.
(Received 24 June 1974) A "dlelecometer-calorimeter" apparatus has been constructed t h a t enables the heat evolution, dielectric permeability, 8', and the conductivity, ~, of a m o n o m e r - p o l y m e r system to be recorded simultaneously during polymerization. The radical polymerization of a number of acrylates, methacrylates and dimethacrylate oligomers has been studied. A correlation has been established between the specific molecular mobility in the monomer-polymer system, a t polymerization to various extents, with the kinetic characteristics of the process.
THv. processes in polymer synthesis do not reduce to the chemical transformation of the monomer molecules to form maeromolecules, but are also accompanied by the formation of the definite supermolecular structure of the polymer. The structural and physical transformations in the monomer-polymer system determine many features of the kinetics of radical polymerization. The effect of structural formation on the kinetics is thus exerted, to a considerable extent, through a change in molecular mobility. In connection with this, the study of the interrelation between physical and chemical kinetics is a present task in the chemical physics of polymers. We have previously [1] suggested a method of studying this interrelation, based on the simultaneous measurement of the dielectric permeability, ~', the conductivity, a, and the heat evolution in the monomer-polymer system during polymerization. It has been established [2-5] with a number of processes in the formation of linear and network polymers as examples, that this method makes it possible to do the following: 1) To assess, from the change in e', both the change in the rotational mobility of the monomer and the polymeric chain molecules and also the transition of the monomer-polymer system from the condition of a molecular solution into the condition of a microheterogeneous dispersion of polymer particles in the monomer; 2) To obtain information about the translational diffusion for the monomer and polymer molecules from the behaviour of a, because of the common features between the mechanisms of electrical conductivity and * Vysokomol. soyed. A17: No. 11, 2425-2433, 1975. 2790
Kinetics of radical polymerization
2791
diffusion; 3) To establish unambiguously the correlation between the change in these forms of molecular movement during the process and the rate of polymerization. The present work is devoted to a generalization of data both new and obtained previously by the "dielecometer-calorimeter" method, in studying of the polymerization of monomers of the acrylic and methacrylic series and dimethacrylate oligomers. The selection of the experimental materials was dictated by the desire to characterize the connection between molecular movement and the kinetics of radical polymerization as a function of the molecular structure of the linear polymers formed (the presence or absence of ~-methyl groups and a variation in the length of the side substituent are known to have a substantial effect on the flexibility of the main chain), and as a function of the formation of any spatial network of chemical bonds and the properties of the block polymers being formed. The considerable differences in the glass transition temperatures, T~, of the polymers formed enabled the polymer-monomer systems (with selected conditions of temperature during polymerization) to be studied both in the highly elastic and also in the glassy conditions, and enabled the effect of the transition of the polymerizate into the glassy condition on the features of the polymerization reaction to be clarified. 2 1
#
3
#
11 I I I I I I t I
I I I I I I I I
L
I
0
b FIo. 1. Block diagram of installation for the simultaneous recording of the polymerization kinetics and the dielectric properties of the monomer-polymer system: a represents the cell; 1 - high voltage electrode; 2--measuring electrode; 3--thermocouple system; 4--polymerizate; 5--insulator; b is the dieleeometer; 6--E8-2 bridge; 7--EG-4 generator; 8 - - E L U R - 3 nul indicator; c is the calorimeter; 9--F-116 DC amplifier; 10--EPP-09.
The simultaneous study of the polymerization kinetics and the dielectric properties was made with equipment combining both a calorimeter and a dieleeometer (Fig. 1). The polymerization kinetics were recorded from the heat evolution in a type UP-2 calorimeter [1]. The dielectric measurements were made with an assembly of stemdard pieces of apparatus.
V . V . KOOltERVINSKII et al.
2792
:For t h e dielectric m e a s u r e m e n t s , t h e s t a n d a r d cell of t h e c a l o r i m e t e r was c o n v e r t e d i n t o a c o n d e n s e r b y i n s t a l l i n g a n i n s u l a t i n g r i n g m a d e of teflon (Fig. 1, 5). I n o r d e r to incrcaso t h o t h e r m M i n s u l a t i o n of t h e r e a c t i o n cell, t h e l a t t e r was c o n n e c t e d w i t h t h e b r i d g e b y s m a l l diam e t e r c o n d u c t o r s (0.2 r a m ) . M e a s u r e m e n t s were carried o u t a t 3 fixed frequencies, n a m e l y , 4 × l 0 ~, l03 a n d 5 × l 0 '~ Hz. T h e dielectric p e r m e a b i l i t y e' ~ a s c a l c u l a t e d f r o m t h e e q u a t i o n : ~" = C 1 - - C e / C 0 - - C e
(
1)
w h e r e C~ is t h e c a p a c i t y of t h e eond(,l~s(~r w i t h the, liquid u n d e r i n v e s t i g a t i o n , p F ; Co is t h e c a p a c i t y of t h e e m p t y c o n d e n s e r ; C e is t h e leakage, c a p a c i t y , c o n s i s t i n g of t h e c a p a c i t y of t h e i n s u l a t o r a n d t h e eapaei~ y of t h e air spaco o u t s i d e t h e v o l u m e of t h e liquid; C~ was d e t e r m i n e d f r o m eqn. (1) for s t a n d a r d liquids (bonzcne, CC14). T h e tangent, of t h e dieh, etrie loss angle, t.an 6, was c a l c u l a t e d f r o m t h e e q u a t i o n : t a n 5 - - a/~o (C~ --Co),
(2)
w h e r e a is c o n d u c t i v i t y , o h m -~ a n d w is t h e a n g u l a r f r e q u e n c y , see -~.
~' ~anc7 e
so
"-..
\
I00
.i!,<
200 7W'me , m/17
I
30{}
:Fro. 2. D e p e n d e n c e of." 1, 2 a n d 3, e'; 1', 2" a n d 3', t a n 6 a n d 4, thc~ e x t o n t of p o l y m e r i z a t i o n o n t h e t i m e of p o l y m e r i z a t i o n of ]~IMA (50°C, 1 o{, B P ) . 1 a n d 1', 4 × 102 Hz; 2 a n d 2", 10 a H z a n d 3 a n d 3', 5 × 10 a Hz. T h e a b s o l u t e e r r o r in m e a s u r e m e n t s of t h e e x t e n t of c o n v e r s i o n , C, was a p p r o x i m a t e l y 3 /o/o , i n e', 0.4 a n d in t a n 6, 0.001; t h e r e l a t i v e e r r o r in t h e m e a s u r e m e n t s of e' wt~s ~0.5°~,. T h e m o n o m e r s were purified b y t h e s t a n d a r d m e t h o d s u s i n g p r c p o l y m e r i z a t i o n , r.rh~, olig o m e r s were purified in s o r p t i o n c o l u m n s for p r e l i m i n a r y a m l fine p u r i f i e a t i o n b y t h e m e t h o d g i v e n in [6]. T h e p u r i t y of t h e p r o d u c t s (the a b s e n c e of i n h i b i t i n g i m p u r i t i e s ) was monitorc d k i n e t i e a l l y [6]. B e n z o y l p e r o x i d e (BP) or d i e y e l o h e x y l p e r o x y d i e a r b o n a t e (CPC) was u s e d as t h e i n i t i a t o r of p o l y m e r i z a t i o n , d e p e n d i n g o n t h e t e m p e r a t u r e of t h e e x p e r i m e n t . ,The exp e r i m e n t s were c a r r i e d o u t i n a n a t m o s p h e r e of a r g o n .
2793
Kinetics of radical polymerization
e', tan 5 and the degree of conversion (C) were recorded as functions of the polymerization time (Fig. 2). The results were analysed from the way in which e', tan 5 and w/[M] (w being the polymerization rate and [M] being the monomer concentration) depended on the degree of conversion. L e t us s t a r t the diseu ssion of the results o b t a i n e d with the d a t a for t h e p o l y m e r i zatic, n of MMA. I t m a y be seen front Fig. 3a, a n d c, t h a t all t h r e e quantities m e a s ured (c', ta~ 6 a n d w/[M]) are c h a r a c t e r i z e d b y t h r e e regions of different b e h a v i o u r durL,~!., the process. Region I is c h a r a c t e r i z e d b y a slight fall in c' a n d a s h a r p reduel.ion in tan 5. An a n o m a l o u s increase in e', r e l a t e d to the a u t o a e e e l e r a t i o n stage i~ the re~etion, ~md a slight, decrease in t a n 6 are o b s e r v e d in region I f . Finally, in region I I I , we n o t e a slight increase in tan 6 and a m a r k e d fall in c', which is a c c o m p a n i e d b y a slowi~g down of the reaction. Region I. I t is k n o w n f r o m the t h e o r y of dielectrics [7] t h a t tan d=
,~:~i c0 -c~:, l ~ (~,)r)::
-
(3) '
where ~, a n d c:~ are the static a n d high f r e q u e n c y dielectric permeabilibies; Yv is the specific ¥ o l u m e c o n d l ' c l i v i t y , o h m -~.cm-~; z is the r e l a x a t i o n time, sec-~; a n d (.,) is t h e fl'e
2794
V . V . KOCHERVINSKII et al.
<¢
f,n 6', fOz
/<
~l ~Mj~lo~, ,.i,~-~ fan
f
-20
L.6 -.600
5.0
4.5
/~
t
G
-
l
17,
I
I
-300
i
4.0
0.5
-\if
3-0
2O
-10 -200
4-
/00
40
c' L
20
80
C,%
40
60
6O 0,%
w,/{M]n~,mi'~'~
c
~Z
70
-30
,.,t
0.0 -
\/,
g, x.
~ .0 5- -20
-/500
6.5
4
-10
I
I
i
,50
I
I
i
I00
O, %
i- -500
2O
4O
GO
o,%
FzG. 3. Dependence of: 1, 2 and 3, e'; 1', 2" and 3', tan ~; 4, w/[M] and 5, the radius of the polymerization particles R on the extent of polymerization, C, for the following: a and b --MMA; c--BMA; d--MA; e - - B A ; f - - T G M - 3 ; g--MGPh-9; h - - M B under various conditions: a--30°C, 1% CPC, f--108 Hz; b--50°C, I~o BP; c--50°C, 1.72% BP; d, e--30°C, 0.3% CPC; b, c and d--frequencies as follows: 1, 1 ' - - 4 X 103 Hz; 2, 2'--103 Hz; 3, 3 ' - - 5 X 103 Hz;f--70°C, 0"035~o BP, f = 103 I-Iz; g--50°C, 0-023~o CPC, 103 Hz; h--70°C, 0-012~o BP, 10a Hz.
Kinetics of radical polymerization
2795
~r
5'0
_
,~00
"7
7
-- 300
/0- -zgo0
- ~ .
1.0-200
-1500
5--/000
/X
-500
1
[
I
L
L
i
I
40 C,%
8O
!
l
[
i
50
i
i
I
fog
C,%
h
5°I
Y £'
w
hn8 wlFM3,1o mi.-, - gO
l ~ m i n "I "land
0.5 -
d.5 /
4.0
tx~,~f 50
5d ,o/00
30
L.,%
50
-
C,%gO
FIG. 3
amounts to several orders of magnitude at the same polymer concentrations. Conductivity measurements clearly give information about the change in microviscosity during polymerization, whith is a decisive factor in the transport of monomer molecules to the macroradical. Since the reduction in the coefficient of translational diffusion in region I is not accompanied by any appreciable change
2796
V.V.
KOCHERVINSKII et
at.
in the reaction rate, it may be concluded that chain propagation is not diffusion contro]led at this stage. In order to analyse the dielectric permeability during polymerizati(m, we shall take advantage of the equation [7]: 09
e'=e~ + (Co--Zo~) ~ f(r)dr/1 + (o)r) 2,
(4)
o
where f (r) is the distribution function of rela×ati(;n times. For :o~ <~l e'--c(), that is, the dielectric permeability in region I characterizes the static dielectric permeability. With the condition that the permeability is additive ibr the polymer-monomer system in the case of a nlolecl~iar solution, it may be represented in the form: , 2eo ( c ~ + 2 \ 2 ~o-eo~±~-:-| ., / Z%-i-e~\ o /
=~~-, ( ~--z)/fl,': 4 ~ 5 .: o i. L'~;/~:,,I -
3kT
] '
(5)
where N o is the number of dipoles in unit volume, g~ and x are the effective dipole moment of the monomer and its fraction in solution respectively, /q, and (l--x) are the effective dipole moment per monomer unit in the polymeric chain and the proportion of the polymer in solution respect.ively. The value of #p for the polymer is known to be always less than /,~f !br the monomer because of enhanced intra- and intermolecular inters~:.tio~Ls [9]. An increase in the proportion of the component with the lower value of g, which occurs during polymerization, must, according to eqn. (5), lead to a reduction in e0 (that is, d), as is observed in region I. An anomalous increase in e' is, however, observed in region II. The appearance of the positive increment in the dielectric permeability has been explained [2-5] by the formation of microheterogeneity in the polymerizate and by the mechanism of Maxwell-Wagner type polarization connected with this. Experimental and theoretical investigations of recent years have, in fact, uncovered the phenomenon of a gigantic low-frequency dispersion in colloidal suspensions of polymeric particles, which may be explained within the framework of the Maxwell-Wagner heterogeneous dielectric model with polarization of a double electric l~yer [10]. Another confirmation of the fact that the polymerizate in region II changes from the molecular solution condition into the condition of a dispersion of polymer particles in the monomer, has been obtained by investigating the turbidity spectra of the polymerizate [11]. It may be seen from Fig. 3b, which shows the dependence of the effective particle radius on the degree of conversion [11], that the region of increasing e' and of increasing particle size belong to the auto-acceleration stage of polymerization. This points to the fact that immobilization of macroradicals in the polymer particles and the reduction in their segmental mobility connected with this lead to a decrease in the constant for termination and to an increase in the polymerization rate. A sharp decrease in dielectric permeability, which is accompanied by a slowing
Kinetics of radical polymerization
2797
down in the reaction, is observed in region III. Since the dielectric permeability is very sensitive to micro-Brownian segmental lnovement, this fact is readily explained b y "freezing-out" of cooperative forms of movement in the frequency range investigated. This indicates that, in the later stages, chain propagation passes into the diffusion-controlled region. In fact, because of the increase in the proportion of structured polymer in the later stages, the transport of monomer units to the reaction sites will depend essentially on the details of segmental movement, since it is precisely through such movements within the polymeric matrix that holes (vacancies) are created, and it is b y these that transfer processes are accomplished [12]. Features of the behaviour of the dielectric properties of polymerizate as a function of the polymeric chain structure. Data from the polymerization of butylmethacrylate (BMA) indicate (Fig. 3c) that here, just as in the case of MMA, the region of uniform decrease in e' belongs to the region where the reaction rate increases slightly. However, with auto-acceleration (less pronounced), the anomalous increase in ~' is not observed, although the deviation of the experimental curves for e' (C) from that calculated from the Debye theory for a molecular solution also points in this case to micro-heterogeneity in the monomer-polymer system [5]. The increase in the volume of the substituent in the ester group on going from MMA to BMA clearly leads to a weakening of inter-chain interactions and impedes macromolecular aggregation. In this connection, micro-heterogeneity should be less pronounced in the BMA polymerizate than in MMA, and this should lead to a smoothing, out in the effects of additional polarization. On the other hand, the absence of an a-methyl group in the PMA chain should lead to an intensification of inter-chain interactions and to the effect of an increase in additional polarization being more clearly expressed than in the case of PMMA. In fact, an increase in dielectric permeability and auto-acceleration of the process are observed even in the earliest stages during the polymerization of methylacrylate (NA) (Fig. 3d). Chemical crosslinking through chain transfer at e-hydrogen may, in this case, make an additional contribution to the aggregation process (one crosslink for each 10a-104 monomer links) [13]. A certain screening of the inter-chain interaction, involving the side group, on going to BA reduces the additional polarization effect (Fig. 3e), although the regular features of the auto-acceleration of the reaction are the same as in the case of MA. The greater flexibility of the polymer chains of acrylic polymers as compared with polymethaerylates is clearly the reason why, in both acrylates, the occurrence of auto-deceleration of the reaction (a maximum rate on the curve for w/[M]) is found at the beginning of the freezing-out of segmental forms of movement at frequencies above approximately 10s Hz. This may be clearly seen from the data for the polymerization of MA (Fig. 3d) where the maximum in the reaction rate
2798
V. ¥. KOC~ERVI~SXIIet al.
ment at the frequency range investigated, since even at limiting degrees of conversion no marked decrease in the dielectric permeability is observed, which would characterize the freezing-out of segmental movement although the reaction occurs, as in the other cases, with auto-deceleration. The process of freezing out of segmental movement in the monomer-polymer system obeys a common relaxation law: the higher the frequency of the superimposed field, the lower the degree of conversion at which the decrease in s' is found. Thus the reaction rate in the auto-deceleration stage is insensitive to the transition of the system into the glassy condition where all forms of segmental movement become frozen. On the contrary, the start of auto-deceleration of the reaction is connected with the freezing out of movements of a specific (critical) frequency, which is different for the various polymers (Fig. 3b-e). In the case of P]~IMA, these are frequencies of the order of 10 a Hz: they are rather higher for PBMA and must be even greater for polyacrylates. An increase in the width of the frequency range investigated would have enabled the critical frequencies to be determined in these cases with greater accuracy. I t should be noted that the increase in the critical frequency of the processes in the series investigated correlates with the glass temperature of the block polymer formed: the lower Tg, the higher the critical frequency. Polymer Tg, °C PMA 8 Polybutylacrylate (PBA) --56 PMM.A 110 PBMA 24 The structural features that determine T~ clearly determine the relaxation times for segmental movement in the ~monomer-polymer system as well. The relaxation time for segmental movements of macroradicals determines the probability of their recombination, that is, the constant for termination, k t. In connection with this, attention should be given to the good correlation between the flexibility of the polymer chains and the rate of anihilation of "trapped" macroradicals. According to the data of Melwille [14], the average lifetime of trapped radicals in PMMA under comparable conditions is more than 5 times greater than the corresponding time in PBA. The rate of annihilation of "imprisoned" macroradicals in PMA is reported to be greater than that in PMMA [15]. It may therefore be concluded that the progressive reduction in chain flexibility in the series of linear polymers investigated on going from P B A to PMMA will be accompalfied b y a regular decrease in k t. The reduction, in the same series, of the critical fiequencies for molecular movement confirms this conclusion. Network polymers. The polymers formed from dimethacrylate-butadiol (MB), dimethacrylate-triethylene glycol (TGM-3) and dimethacrylate-bis-triethylene glycol phthalate (MGPh-9) are characterized b y broad region in which the changeover to the glassy state occurs. The common regular feature which char-
Kinetics of radical polylnerization
2799
racterizes the polymerization of oligo-ester-acrylates is as follows: the beginning of auto-deceleration of the reaction pertains to a degree of conversion when the freezing out of segmental forms of movement has already begun, as judged from the reduction in e' (Fig. 3f-h). This means, according to [3], that the rate of polymerization of oligo-ester-acrylates in the later stages is limited by the low frequency forms themselves of conformational regroupings. A characteristic feature of all the three dimensional polymers investigated is the very wide region of dispersion of ~', characterizing the freezing out of segmental mobility, which sets in in polymers with a network structure when the distance between crosslinks becomes less than the size of the kinetic segment. The broad region of dispersion in ~' is reported [3] to be caused by structural nonuniformity in the oligo-ester-acrylates and is evidence that regions with an enhanced density of crosslinking exist in them even in the early stages of conversion, the distance between the chemical points of attachment being less in these regions than the length of the kinetic segment. It is precisely these regions which are responsible for the reduction in the dielectric permeability in the early stages of the polymerization process. On the other hand, the reduction in ~' that continues in the later stages close to the limiting conversion means that, even at such large conversions, there still exist regions with sparse crosslinking where segmental mobility may be realized. This behaviour of the reaction system is best described within the framework of the following model: 1. The primary linear macromolecules formed, which contain one unreacted double bond for each link (potential sites for branching and crosslinking), aggregate and the aggregates themselves become stabilized by branching and crosslinking reactions, becoming converted into densely crosslinked particles of microgel. Thus even in the earliest stages of conversion, network macromoleeules appear with chain links between the points of attachment less than the kinetic segment. 2. As the densely crosslinked micro-particles (of microgel) accumulate in the reaction system, the density of the network in the spaces between the micro-particles remains very much less (because of local auto-acceleration, of the gel effect type, in the particles, steric hindrances at the particle boundary, the development of microsyneresis within the particles, etc.). In this way, even in the later stages of conversion when the average distance between crosslinks becomes less t h a n the kinetic segment, network macromolecules still remain having a distance between crosslinks greater t h a n the segment. The authors wish to express their thanks to M. P. Berezin for participating in the experimental part of the work. Translated by G. F. MODT.E~ REFERENCES 1. Z. A. KARAPETYAN, V. V. KOCHERVINSKII~ V. P. ROSHCHUPK1N, B. P. SMIRNOV
and G. V. KOROLEV, Vysokomol. soyed. Bl1: 252, 1969 (Not translated in Polymer Sci. U.S.S.R.)
2800
M . T . BRYK et al.
2. V. P. ROSHCHUPKIN, V. V. KOCHERVINSKII, Z. A. KARAPETYAN and G. V. KOROLEV, Vysokomol. soyed. B13: 317, 1971 (Not translated in Polymer Sci. U.S.S.I~.) 3. V. P. ROSHCHUPKIN, V. V. KOCHERVINSKII, O. G. SEL'SKAYA and G. V. KOROLEV, Vysokomol. soyed. B13: 497, 1971 (Not translated in Polymer Sci. U.S.S.R.) 4. V. P. ROSHCHUPKIN and G. V. KOROLEV, Doklad na 18-i konferentsii po vysokomolekulyarnym soyedineniyam (Contribution to the 18th Conference on Polymers). Kazan', 1973 5. V. V. KOCHERVINSKII and Yu. V. ZELENEV, Vysokomol. soyed. A17: 2231, 1975 (Translated in Polymer Sei. U.S.S.R. 14: 10, 1975) 6. G. V. KOROLEV, Dissertation, 1965 7. N. P. BOGORODITSKII, Yu. M. VOLOKOBINSKII, A. A. BOROB'YEV and B. M. TAREYEV, Teoriya dielektrikov (Theory of Di¢~lectries). Izd. "Energiya", 1965 8. V. P. SHUVAYEV, Dissertation, 1968 9. A. A. TAGER, Fiziko-khimiya polimerov (Physical Chemistry of Polymers). Izd. "Khimiya", 1968 10. V. N. SHILOV and S. S. DUKHIN, Kolloidn. zh. 32: 293, 1970; T. L. CHELIDZE and V. N. SHILOV, Kolloidn. zh. 35: 105, 1973 11. B. V. OZERKOVSKII, G. M. CHPLAKHYAN and V. P. ROSHCHUPKIN, Uch. zap. Yerevanskogo gos. un-ta. No. 3, 82. 1974 12. H. L. FRISH, J. Polym(~r Sci. B3: 13, 1965 13. C. BAMFORD, O. BARB, A. ,JENKINS and R. ONYON, Kinetika radikal'noi polimerizatsii vinilovykh soye(lineHii (Kinetics of the ]~adical Polymerization of Vinyl Compounds). Izd. inostr, lit.. 1961 (14ussim~ translation) 14. H. W. MELWILLE, Z. Elektrochem. 60: 276, 1956 15. S, Ye. BRESLER, E. N. KAZBEKOV and Ye. M. SAMINSKII, Vysokomolek. soyed. 1: 136, 1959 (Translated in Polymer Sci. U.S.S.R. h i, 55, 1960)
THERMAL POLYCONDENSATION OF DIPHENYLSILANEDIOL CONTAINING DISPERSED OXIDES OF TITANIUM, IRON, COBALT OR COPPER* M. T. BRYK, I. A. VARAVKOand O. D. KURILE~KO Institute for Colloidal and Water Chemistry, Ukr. S.S.R. Academy of Sciences
(Received 29 August 1974) I R spectroscopy arid thermal analysis have been used to investigate the adsorption interaction between diphenylsilanediols and dispersed oxides of the 3d transition metals. The thermal polycondensation of diphenylsilanediol containing dispersed oxides has been investigated and it has been shown that the mechanism of polycondensation of the monomer depends on the characteristics of the adsorption interaction between it and the oxide surface. The struetur(., molecular weights and degree of grafting of the polymer formed in the presence of the specified oxides have been studied. * Vysokomol. soyed. A17: :No. 11, 2434-2440, 1975.