Synthesis of a polycarbonate from phenolphthalein and phosgene by low temperature polycondensation

Synthesis of polycarbonate

3069

REFERENCES ]. K. HESS, H. MAHL and E. GliTTER, Kolloid-Z. und Z. Polymere 155: 1, 1957 2. V. R. REGEL' and A. I. SLUTSKER, Fizika segodnya i zavtra (Physics Today and Tomorrow), p. 90, Izd. "Nauka", 1973 3. G. S. Y. YEH, J. Macromolec. Sci. 6: 465, 1972 4. S. A. ARZHAKOV, N. F. BAKEYEV and V. A. KABANOV, Vysokomol. soyed. A15: 1154, 1973 (Translated in Polymer Sci. U.S.S.R. 15: 5, 1296, 1973) 5. Yu. S. NADEZHIN, A. V. SIDOR0VICH and Ye. V. KUVSHINSKII, Vysokomol. soyed. BI5: 724, 1973 (Not translated in Polymer SoL U.S.S.R.) 6. V. N. TSVETKOV and S. Ya. KOTLYAR, Zh. fiz. khim. 30: 1120, 1956 7. A. V. SIDOROVICH and Ye. V. KUVSHINSKII, Relaksatsionnye yavleniya v polimerakh (Relaxational Phenomena in Polymers). p. 63, Izd. "Khimiya", 1972; Yu. A. SHARONOV and M. V. VOLKENSHTEIN, Vysokomol. soyed. 4: 917, 1962 (Not translated in Polymer Sci. U.S.S.R.); Fizika tverdogo tela 5: 590, 1963 8. B. K. VAINSHTEIN, Difraktsiya rentgenovykh luchei n a tsepnykh molekulakh (Diffraction of X-rays in Chain Molecules). p. 343, Izd. Akad. Nauk SSSR, 1963

SYNTHESIS OF A POLYCARBONATE FROM PHENOLPHTHALEIN AND PHOSGENE BY LOW TEMPERATURE POLYCONDENSATION* O. V. SMIR~OVA, O. G. FORTUlqATOV, V. V. K()RStfAK a n d 0 . A. AGAPOV D. I. Mendeleyev Institute of Chemical Technology, Moscow

(Received 2 July 1974} The effect of the nature of the tertiary amine and of the organic solvent on the preparation of polycarbonates by low temperature polycondensation, has been investigated. I t is shown that //red is dependent on the pKa of the bisphenol reactant and on the thermodynamic stability of its complexes with the amine. I t was found that the optimal q u a n t i t y of triethylamine increases exponentially as the q u a n t i t y of phosgene in the polycondensation system is 'increased and is dependent on the polarity of the organic solvent used. When tertiary amines of different basicity are used the optimal q u a n t i t y of the latter increases as the basieity of the amine increases.

Ilq RECE:NT time a number of papers has been concerned with the preparation of polyesters in an organic solvent, using as catalyst and acceptor a tertiary amine in quantities equal to or greater than the stoichiometric amount with respect to the main reactants. There is however very little information on the preparation of polycarbonates (PCs) by this method [1-3] and it does not enable a detailed view of the chemistry of the process to be formulated. It was reported in reference [4] that when polyarylates are prepared b y * Vysokomol. soyed. AI7: No. 12, 2669-2675, 1975.

3070

O. V. SMIRr;OVA et al.

acceptor catalytic polycondensation, the molecular weight of the polymer is dependent to a considerable extent on the nature of the solvent used. In the present paper we report a study of some correlations in and the chemistry of the synthesis of PCs in an organic solvent at 20 °, in relation to the nature of the tertiary amine, the reactivity of the original reactants and of the products of their reaction with the amine, and also the nature of the solvent. I t was shown in references [3] and [5] that when triethylamine (TEA) is added in stoichiometric proportion to a solution of a bisphenol in an organic solvent, a complex with the molar ratio of the components of 2 : 1 is formed. When phosgene is added to a solution of this complex in an organic solvent formation of a PC occurs b y the entirely base catalysed mechanism, in which the active centre is a complex formed b y hydrogen bonding or the phenoxyl ion of an ion pair, according to the scheme +

+

l l O - - A r - - O I t + 2NRa ~ R a N . . . t t O - - A r - - O H ~- R a N I I . . . O- - - A r - - O - , . . I t N R a

I --Ar--OH...

N Ra

5+ + CI--C--CI

--Ar--(} ~

""

I .H

I

5 d I C l - - C - - I CI

-II L_t

-Ill

~/)

-A)

+ ' " NRa --+ - - A r O C - - C I + [ItNRa] Cl~ II O

or +

--Ar--O..

• tINRa

+

+

--Ar--O. • •

tIN Ra

I

iS+ CI--C--CI

-o,,t

CI--C--

FII

---, - - A r O C - - C l + [[INlla] CICI

T

O

,O

On the basis of the above all-base mechanism of the catalytic effect of TEA in preparation of a PC in an organic solvent it m a y be assumed that a PC of highest molecular weight will be obtained when a complex of TEA with a bisphenol whose pKa is minimal and the thermodynamic stability of the complex is maximal, which creates the most favourable prerequisite for formation in the solution of the phenoxyl ion of the ion pair and for nucleophilic attack b y the complex on the electron deficient acid chloride component. From the results obtained it follows that PCs with highest t/red are formed when more acidic bisphenols are used (Table 1). The dependence of r/red on the pKa of the bisphenol is linear, with a coefficient of correlation, calculated b y the method of least squares, of 0.86 (Fig. la). These results also confirm the dependence of//red of the PC on the energy of activation for decomposition of the isolatmd bisphenol-TEA complexes (Fig. lb), which is characteristic of the all base-mechanism of the catalytic effect of TEA. The results presented in Table 1

Synthesis of polycarbonate

3071

were obtained using bisphenols of different reactivity (pKa), the polycondensation being carried out in dichloroethane. I n subsequent work the bisphenol used was phenolphthalein (PP), the optimal concentration of which for production of a PC with maximal ~red is 0"4 mole/1, at a molar ratio of bisphenol : TEA : phosgene of I : 3 : 1-5 (Fig. 2). T A B L E 1. D E P E N D E N C E OF tired A N D T H E Y I E L D OF P C s ON T H E R E A C T I V I T Y OF THw. B I S P H E N O L S A N D T H E S T A B I L I T Y OF T H E I R C O M P L E X E S W I T H

TEA

(Solvent--dichloroethane, bisphenol concentration--0.45 mole/1, molar ratio of bisphenol : : phosgene : T E A = 1 : 1.5 : 3"0)

Expt. No.

pKa of bisphenol in E t O H

Bisphenol

Yield,

kcal/ /mole

dl/g

%

8-30

10.54

0"28

90

8.67

23.0

0"30

89

8-90 8.97

12.0 19.9

0"24 0"32

9O 92

9.17 9.25

18.3 15.5

0"30 0"24

94 91

9.38 9-46 10.05

13.5 16.8 10.3

0"26 0"24 0"20

92 83 9O

[3] 2,2-bis-(4-Hydroxy-3-chlorophenyl)propane bis-(4-Hydroxy-3-chlorophenyl)methylphenylmethane bis- (4-Hydroxy-3-methylphenyl)methylphenylmethane Phenolphthalein bis-(4-Hydroxyphenyl)methylphenylmethane 2,2-bis- (4-Hydroxyphenyl)propane 1,1-bis-(4-Hydroxy-3-chlorophenyl)cyclohexane 9, 9-bis- (4-Hydroxyphenyl )fluorene 1,1-bis-4 -(Hydroxyphenyl)cyclohexane

* The values axe for complexes of 1 : 1 equimolax composition [~]. t All experiments were conducted under conditions that are optimal for synthesis of a PC from bis-(4-hydroxyphenyl)methylphenylmethane [2].

I n conducting low temperature polycondensation in the presence of TEA the optimal quantity of the latter is specific to each concentration of phosgene. I n all instances increase in the concentration of the amine above the optimal led to a sharp fall in t/red and in the yield of the PC (Fig. 3). Increase in the quant i t y of TEA in the system requires increase in the concentration of phosgene. This is because of the ability of TEA to react vigorously with phosgene at room temperature, resulting. According to reference [6], in decomposition of the l a t e r as follows: 1~ (C2H5)3-]-COC12 ~- (C2Hs)sN'COCI~ (1) C~Hs (CIH,)sN" COCII -~ CIH5

O

/

N--C--CI+C2HsCI

(2)

O. V. SM:[RNOVA.et aL

3072

N,N-Diethylcarbaminoyl chloride, formed by reaction (2) is a monofunctional compound and, as was shown in reference [7], in the preparation of PCs in organic solvents it plays the part of a chain growth regulator C.211s

\~-c-c~-t- R~u. C',Ha

~-//-\\-

R-.~=--\\ o

0

0

Therefore each quantity of TEA taken for the reaction must have its own optimal concentration of phosgene, as is well illustrated by the results depicted in Fig, 4. '7red, d ~

G

0"38~

b

z/

1o

-

#5~o2

70

2/o0. e I

8

9

lOpg a

10

FIG. 1

l

I

18 26 Eo. , I~ca//mole

0"2

O'Zt

[PP], mo;e/L

0.6

FIG. 2

:FIG. 1. Dependence of t/red of a PC on the p K a of the bisphenol (a) a n d on the energy of activ a t i o n for decomposition of its complex w i t h T E A (b). The figures at the points are the exp e r i m e n t n u m b e r s in Table 1. :FIo. 2. Dependence of t/red (1, 3) a n d of the yield of a PC (2, 4) o n the c o n c e n t r a t i o n of P P a t the molar ratio of p h e n o l p h t h a l e i n : T E A : phosgene of 1 : 3 : 1.5, in dichloroethane (1, 2) a n d dioxane (3, 4).

All the above results relate to the use as catalyst of TEA, which is of high basicity (pKa= 10.72) and easily reacts with the bisphenol reactants of different structure, to form a complex. Here TEA is consumed not only in formation of the complex, but also in reacting with phosgene, leading in addition to disturbance of the optimal conditions for the synthesis and removal of this component from the sphere of reaction to formation of reactive intermediate products t h a t are also capable of stopping growth of the macromolecules. This explains the exponential nature of the dependence of the optimal concentration of phosgene on the quantity of TEA (Fig. 4). In synthesis of polyarylates in organic solvents in the presence of weakly basic tertiary amines the nucleophilic mechanism of catalysis by the amine is

Synthesis of polycarbonate

3073

more probable [8]. To discover the effect of tertiary amines of different n a t u r e in the reaction between P P a n d phosgene, amines forming the following series were t a k e n as catalysts : T E A > t r i b u t y l a m i n e > 2,3-dimethylpyridine > pyridine :> > N , N - d i m e t h y l a n i l i n e . The experiments were conducted at concentrations of P P a n d phosgene t h a t were optimal with respect to TEA. ~red,dl/J

Y/e/d, %

0"32

90

'-

3

2 5

0'24 1

#3

70

0.18~

5

50~ 08

1"2 16 TEA,mole/L

I

I

;

1'5

2"5

3"5

J

Z.O

I I I'Z 16 TEA,mo/e//.

0"8

I

q'5

I

2.0

__l . . . .

i

I

I

1"5

2"5

3"5

~'5

TEA:PP, mo]e/mole

__

TEA:PPmo/e~hT~o/e

FIG. 3. Dependence of tired (•) and the yield of a PC (b) on the concentration of TEA at the molar ratios of: P P : T E A o f l : l (1); 1:1.5 (2); 1:2.0 (3); 1:2'5 (4) and 1:3.0 (5).Concentration of PP 0.4 mole/1, phosgene concentration 0.6 mole/1., solvent- dichloroethane. W h e n t r i b u t y l a m i n e a n d N,N-dimethylaniline were used no polycarbonates were formed (Table 2). At room t e m p e r a t u r e however these amines react with phosgene to form complexes of similar composition a n d with a similar decom[COCI2],mo/e/L ~red, dl/9

1 1.2

0.32 l

0.8

0.2~

3

0.16

2

f

0.4 I

O.Zl

I

l.Z 2-0 TEA, mo/e/L FIG. 4

I

2

--

~

1

I

3

#

5

A,m[ne ~rno!e/mo/e of PP FIG. 5

FIG. 4. Dependence of the optimal concentration of phosgene on the quantity of TEA in the polycondensation system. Fro. 5. Dependence of tired of a PC on the quantity of TEA (1), 2,3-dimethylpyridme (2) and pyridine (3). Bisphenol concentration 0.4 mole/1.; COCls concentration 0.6 mole/l.

3074

O . V . S M I R ~ O V A et al.

position mechanism (reactions (1) and (2)) [9]. This interaction and the absence of polymer when an excess of tributylamine or N,N-dimethylaniline in the quantity o f 5 moles per mole of bisphenol is used leads to the conclusion t h a t when phosgene T A B L E 2. D E P E N D E N C E OF tlred AND T H E Y I E L D OF A

PC BASED

ON PHENOLFHPHA_LEIlq Olq T H E

Q U A N T I T Y AND N A T U R E OF T H E T E R T I A R Y A M I N E

Amine, mole/ /mole of bisphenol 2.5 3.0 3.5 4.0 5.0

Triethylamine (pKB= 10.72 [10]) /]red,

dl/g

yield, ~/o

0.25 O-34 O.30 0.28 0.27

76 84 89 86 82

2,3-Dimethylpyridine (pKB= 6"50) /']red, dl/g yield, % 0.16 0.18 0.22 0.20 0.15

75 78 83 87 82

;

Pyridine (pKB= 5"23) /]red,

dl/g

yield, %

0"17 0"18 0"20 0"26 0"23

72 74 79 85 81

is added to a solution containing P P and a weakly basic amine nucleophilic catalysis, as in aeylation, does not take place. I t was pointed out in reference [2] t h a t steric factors have a large effect on the conditions of formation of a bisphenol-tertiary amine complex. I R spectroscopical analysis of mixtures of

1"6

!

"~ 1"2

5

I

I

7

9

I

_

II

pKB

FIG. 6. Dependence of the optimal quantity of tertiary amine in the polycondensation system on its basicity: 1--pyridine, 2--2,3-dimethylpyridine, 3--TEA. P P with t r i b u t y l a m i n e and N,N-dimethylaniline in the molar ratios of 1 : 1 a n d 1 : 5 shows the absence of the band at 2400-2600 cm -1, characteristic of the ionized form of the complex, which is the reactive centre in low temperature polycondensation systems. I t is obvious t h a t this is due to the spatial effect of the C4H9 and CH 3 groups in tributylamine and N,N-dimethylaniline, preventing hydrogen bonding between these amines and the hydroxyl groups of the bisphenols. I t is seen from Figs. 5 and 6 t h a t the optimal quantity of a tertiary amine for obtaining a PC with maximal tired increases as the basicity of-the amine

Synthesis of polycarbonate

3075

falls. Also the dependence of r]red Oil the quantity of amine in the polycondensation system is still expressed by curves containing a maximum (Fig. 5). This can be explained by increase in the basicity of the medium and increase in its polarizing effect as the concentration of tertiary amine is increased. This should promote increase in the degree of ionization of the tertiary amine-bisphenol complex and displacement of the - - A r - - O H + N H 3 ~ - - A r - - O H . . N R a ~ - - A r - --

+

--O...NHR3 equilibrium toward formation of the ion pair [11]. This is clearly confirmed by the infrared spectra of mixtures of P P with pyridine and with 2,3-dimethylaniline. The intensity of the NH group band in the 2400-2600 cm -1 region increases as the molar content of tertiary amine in the mixture is increased, while the concentration of the bisphenol is kept constant. TABLE

3. I N T E N S I T Y

AND FREQUENCY

COMPLEX

(1 : 2) I N

SHIFT OF THE ABSORPTION

RELATION

TO THE POLARITY

1M[AXIMU~ O F T H E

PP-TEA

OF THE SOLVENT

(Concentration of complex 0.05 mole/1, 20°. Cell thickness d~ 0-64 cm. AVertwas measured with respect to the frequency of the absorption of the free 0H-group at 3600 cm -1, PP : phosgene= 1 : 1)

Solvent

Absorp- I Dipole Ionization tion maxi- I moment •, potential mum of the I debye [12] J, eV [13] --OH... NR3, cm-1

Absorption maximum + ,d YOH cm-1

Nitrobenzene

3.99

11.7

3225

375

1,2-Dichloroetha~e

2-06

10.0

2940

660

Methylene chloride

1.55

10.35

3210

390

Chloroform

1.15

11.42

2990

610

Benzene

0

9.24

2985

615

of the --NH-- group absorption, % 2475 2620 2485 2595 2480 2580 2515 2600 2470 2580

39 55 80 53

68 73 45 41 10 13

On the basis of the results of I R spectroscopy and the increase in the optimal q u a n t i t y of tertiary amine on passing from more to less basic amines (Fig. 6), it may be supposed t h a t when the same amine is used in preparation of a PC by low temperature polycondensation, the optimal quantity of the amine must also be dependent on the nature of the solvent, the solvating power of which must affect the conditions of formation and the quantity of bisphenol-amine complex in the ionized form. To investigate the effect of the solvent on the optimal concentration of tertiary amine in the polycondensation system and on formation of the original complex the I R spectrum of the P P - T E A complex in the molar ratio of 1 : 2 was recorded in the frequency regions characteristic of formation of the - - A r - - O H . . . N R a

3076

O . V . SMIRNOVA et al. +

complex and of its presence in the ionized form - - A r - - O . . . H N R a , in the solvents nitrobenzene, dich!oroethane, methylene chloride, chloroform and benzene. A series of experiments on preparation of the polycarbonate was carried out in the same solvents. Infrared spectroscopy showed (Table 3) that the magnitude of the shift A Veil of the absorption band of the hydroxyl group, which functions as a proton donor in formation of the bisphenol-TEA complex, and the intensity of the +

--NI-I ammonium group band, which gives a measure of the relative amount of the complex in the ionized form, can serve only as qualitative indices for assessment of the effect of the polarity of the solvent used, on the conditions of formation of the P P - T E A complex. Satisfactory linear correlation between the magni+ rude of the shift Avert of the complex or the intensity of absorption b y - - N H groups and the dipole moment (or ionization potential) of the solvent is not obtained. I t is evident that when the solvent ceases to be an inert medium it is necessary to take account of the thermodynamic non-ideality of the solutions [14, 15] and of the specific interaction of the components of the complex-formation reaction with the solvent [15-17], where the solvent can be a donor of electrons, solvating the bisphenol, or a donor of protons, interacting with the TEA, such as chloroform for example [18].

~r~d dl/g 0.12

2

O.lO

0.08 5 I

I

I

1"7 2"1 2.5 TEA ,mole/mole of PP

I

2"8

FIG. "]. D e p e n d e n c e of Fired of a P C o n t h e o p t i m a l c o n c e n t r a t i o n of T E A : 1 -- n i t r o b e n zene; 2 - - 1 , 2 - d i c h l o r o e t h a n e 3 - - m e t h y l e n e chloride; g - - c h l o r o f o r m ; 5 - - b e n z e n e ; P P a n d COC12 0-4 mole/1, each.

Results obtained from preparation of PCs in solvents of different polarity showed (Fig. 7) that despite the fact that linear correlation between ?]red of the PC, the dipole moment of the solvent and the optimal quantity of TEA required for the reaction is not found, t/red shows a clear tendency to increase as the polarity of the solvent increases, an increase being found over the series benzene~chlorof o r m ~ m e t h y l e n e chloride~dichloroethane. Also increase in the intensity of the

Synthesis of polycarbonate

3077

a m m o n i u m - b a n d m a x i m u m , c h a r a c t e r i s t i c of t h e presence of the c o m p l e x in t h e ionized form, occurs o v e r the s a m e series (Table 3). I n s u m m a r i z i n g t h e a b o v e results the following points m u s t be noted. W h e n p h o s g e n e is a d d e d to a solution of the b i s p h e n o l - T E A c o m p l e x in a n organic solvent, the r e a c t i o n centre of the low t e m p e r a t u r e p o l y c o n d e n s a t i o n s y s t e m is a c o m p l e x f o r m e d b y h y d r o g e n b o n d i n g of a n O H g r o u p of t h e bisphenol to T E A , or t h e p h e n o x y l ion of a n ion p a i r in which a n O H g r o u p functions as a p r o t o n d o n o r a n d f o r m a t i o n of the PC occurs b y t h e all base c a t a l y s e d m e c h a n i s m . Also ?~redof t h e PC increases linearly as the a c i d i t y of the bisphenol a n d t h e t h e r m o d y n a m i c s t a b i l i t y of the b i s p h e n o l - T E A c o m p l e x increase. E a c h q u a n t i t y of phosgene used for the p r e p a r a t i o n of a PC in a n organic solv e n t m u s t h a v e its own o p t i m a l c o n c e n t r a t i o n of T E A , which increases e x p o n e n tially as t h e q u a n t i t y of phosgene in the p o l y c o n d e n s a t i o n s y s t e m is increased. W h e n t e r t i a r y a m i n e s of different b a s i c i t y arc used, t h e o p t i m a l q u a n t i t y of these r e q u i r e d to p r o d u c e a PC of m a x i m a l Yr0d increases as t h e b a s i c i t y of t h e a m i n e decreases. F o r t h e s a m e a m i n e (TEA) its o p t i m a l q u a n t i t y is d e p e n d e n t also on the don o r - a c c e p t o r p r o p e r t i e s of the solvent used a n d it a p p r o a c h e s the stoichiometric q u a n t i t y as the p o l a r i t y of the l a t t e r is increased. Translated by E. O. PHILLIPS REFERENCES

1. M. MATZNER, J. Appl Polymer Sci. 9: 3295, 1965 2. O. V. SMIRNOVA, O. C. FORTUNATOV, T. Tu. KALASHNIKOVA and G. S. KOLESNIKOV, Vysokomol. soyed. A14: 1320, 1972 (Translated in Polymer Sci. U.S.S.R, 14: 6,

1480, 1972) 3. V. V, KORSHAK, A. P. KRESHKOV, O. V. SMIRNOVA. O. G. FORUNATOV, N. Sh. ALDAROVA, M. V. SLAVGORODSKAYA and A. Ye. PAVLOVA, Vysokomol. soyed. A14: 1503, 1972 (Translated ill Polymer Sei. U.S.S.R. 14: 7, 1684, 1972) 4. S. V. VINOGRADOVA, V. V. KORSHAK, A. V. VASIL'EV and V. A. VASNEV, Vysokotool. soyed. A15: 2015, 1973 (Translated in Polymer Sci. U.S.S.R. 15: 9, 2275, 1973) 5. O. G. FORTUNATOV, G. S. KOLESNIKOV and O. V. SMIRNOVA, Vysokomol. soyed. A l l : 1063, 1969 (Translated in Polymer Sci. U.S.S.R. 11: 5, 1204, 1969) 6. Yu. A. STREPIKHEYEV and T. A. PERLOVA, Zh. obshch, khim. 40: 372, 1970 7. G. S. KOLESNIKOV, O. V. SMIRNOVA and O. G. FORTUNATOV, Vysokomol. soyed. A10: 1505, 1968 (Translated in Polymer Sci. U.S.S.R. 10: 7, 1441, 1968) 8. S. V. VINOGRADOVA, V. A. VASNEV, T. I. MITAISHVILI and A. V. VASIL'EV, International Symposium on Macromolecular Chemistry, p. 239, Budapest, 1969 9. Yu. A. STREPIKHEYEV, Dissertation, 1972 10. X. A. WEISSBERG (Ed.), Ustanovlenie struktury organicheskikh soyedinenii fizicheskimi i khimicheskimi metodami (Determination of the Structure of Organic Compounds by Physical and Chemical Methods). Vol. 1, p. 386, Izd. "Khimiya", 1967 (Russian translation) 11. H. BABA, A. MATSIJAMA and H. KOKOBUN, J. Chem. Phys. 41: 895, 1964 12. A. WEISSBERGER, E. PROSKAUER, J. A. RIDDICK and E. E. TOOPS, Organieheskio rastvoriteli (Organic Solvents), Foreign Literature Publishing House, 1958 (Russia~ translation)

3078

YE. I. RYIYMTSEVet al.

13. Energiya r a z r y v a khimicheshikh svazei. Potentsialy ionizatsii i srodstvo k elektronu. (Energy of R u p t u r e of Chemical Bonds. Ionization Potentials and Affinity with the Electron). Izd. Akad. N a u k SSSR, 1962 14. M. HANNA and A. ASHBAUGH, J. Phys. Chem. 68: 811, 1964 15. D. DRAGO, R. CARLSON and N. ROSE, J. Amer. Chem. Soc. 83: 3572, 1961 16. S. CARTER, J. Chem. Soc. A: 404, 1968 17. R. BISHOP and L. SUTTON, J. Chem. Soc., 6100, 1964 18. R. FOSTER, Chem. Ind. 41: 1492, 1959

THE DIELECTRIC PROPERTIES, EQUILIBRIUM AND KINETIC RIGIDITIES OF ETHYL CELLULOSE MOLECULES IN SOLUTION* Y E . 1. RYUMTSEV, F . ~ ° ALIEV, ~ . G. VITOVSKArA, E . U . T~RII~OV a n d V. N . TSVETKOV Physics Institute, A. A. Zhdanov State University, Leningrad H i g h Polymers Institute, U.S.S.R. Academy of Sciences

(Received 13 July 1974) The hydrodynamic and dielectric properties of solutions of ethyl cellulose (EC) fractions in dioxane and ethyl acetate have been investigated. The experimental dependence of the kinetic friction coefficient on the molecular weight is used to determine the equilibrium rigidity of the EC maeromolecules. The number of monomer units present in the chain segment is s = 35. The dielectric behaviour of the EC solutions has been found to be typical of rigid chain polymers. The experimental dependence of the dipole moment (~2), on the mol.wt, led to the conclusion t h a t the dimensions of the geometrical chain segments coincide with the "electrical". A dependence has been found of the dielectric relaxation time v on the mol.wt, which points to a high kinetic rigidity of the EC molecular chains.

EARLIER studies of the electro-optical [1, 2] and dielectric [3] properties of various cellulose ether solutions had shown their molecules to be characterized b y a high equilibrium and kinetic rigidity. The main mechanism of polarization of such solutions in an electrical field was consequently a rotation of the macromolecules as a whole (orientational mechanism [4]). The dielectric polarization studies of cellulose carbanilate (CC) solutions [3] established that dipolar polarization b y a deformation mechanism can occur in addition to the orientational mechanism of polarization [4] and that small scale intramolecular movements are responsible for it. This study deals with the main mechanisms of dielectric polarization of ethyl * Vysokomol. soyed. AI7: No. 12, 2676-2681, 1975.