Preparation and electrophysical properties of some poly-(Schiff's bases)

PREPARATION AND ELECTROPHYSICAL PROPERTIES OF SOME POLY-(SCHIFF'S BASES)* B. E. I)AVYDOV, B. A. KRENTSEL', YU. A. POPOV and L. V. PROKOF'EVA Institute of Petroleum-Chemical Synthesis, U.S.S.R. Academy of Sciences

(Received 31 July 1961)

RECENTLY, polymers with a system of conjugated double bonds in the main chain have been attracting ever greater attention from investigators. A number of papers [1, 2, 3, 4] has been devoted to the production of such polymers and the investigation of their properties. In a series of papers [5, 6] it has been shown that polymers with a system of conjugated --C----C-- and --C----N-- bonds possess interesting electrophysical--particularly semiconductor--properties. We have previously directed attention to the importance for the conductivity of polymeric substances of the presence of heteroatoms in the main chain of polyconjugation--in particular, nitrogen atoms with their unpaired electrons [8]. In order to elucidate the role of heteroatoms in the main chain of polyconj ugation and their participation in the overall process of conduction, the synthesis and investigation of a series of polymeric materials containing the - - C = N - group in the main chain of polyconjugation are being carried out in our laboratory. For this purpose, polyazines modelling the system of bonds --C----N--N=C--, polynitriles, modelling the system of bonds --C----N--C ~-N--, and paracyanogen, modelling the system N N N \c// \c ~ \c ~ \c J

I

I

C

I

C

C%

I

C%

are being studied. In this connection, it was of interest to synthesise and study the electrophysical properties of poly-(Schiff's bases), representing a model system of the polyconjugation of - - C = N - - groups with aromatic rings: or

R R

A~

(where R = H , CHa, Cells, etc.). * Vysokomol. soyed. 5: No. 3, 321-324, 1963. 970

P r e p a r a t i o n a n d p r o p e r t i e s o f s o m e p o l y - ( S c h i f f ' s ba~es)

971

Certain questions of the synthesis of poly-(Schiff's bases) have been discussed in the literature. Bayer [9] obtained black insoluble poly-(Schiff's bases) by the reaction of diand triaminophenols with glyoxal. Marvel [10] obtained heat-stable polymers by the polycondensation of 5,5-methylene-bis-salicylaldehyde with o-phenylenediamine. Greber [11] has investigated the reaction of terephthalaldehyde with aliphatic diamines. In the present work, we have synthesized and investigated the poly-(Schiff's bases) obtained by the polycondensation of p-phenylenediamine (PPDA) with a number of carbonyl compounds: diacetyl (O=C--C----O) terephthalaldehyde,

I I

CH3 CH3 OHC--~

~ ) - - C H O ; and glyoxal, OHC--CHO.

The product of the condensation of PPDA with glyoxal (P-3) consists of a black powder, while that with diaeetal (P-l) is brown, and that with terephthalaldehyde (P-2)is yellow. These substances (P-l, P-2, and P-3) dissolve in sulphurie acid and P-1 and P-2 also dissolve in formic and phosphoric acids. Table 1 gives the elementary composition of the materials obtained and approximate data on the degree of polymerization. TABLE 1. ELEMENTARY COMPOSITION OF THE POLYMERS OBTAINED

Polymer

P-1 P-2

Formula calculated for the dimers C~0N~H280 C2sN4H200

Calculated,% C 71.83 78.30

H 6.59 5.12

Found, % N

C

1 6 . 7 71.72 13.00 78.56

H 6.68 5.15

N 15-17 12-47

iVote. The elementary composition of product P-3 is not given, since the samples did not burn completely.

The IR spectra show the presence in substances P-l-P-3 of conjugated (double bonds ---C--C= (band at 1603 cm-1), 1,4-substituted benzene rings bands at 837 cm -1 and 1511 cm -1) and, in substance P-l, methyl radicals (band at 1378 cm-1). The results of an X-ray analysis showed that P-1 and P-2 have a crystalline structure, while P-3 is amorphous. An investigation of the E P R spectra for substances P-l-P-3 was carried out. The product of the condensation of glyoxal with PPDA (P-3) gives a single narrow E P R signal characterizing the de]ocalization of electrons in a system of conjugated bonds (Fig. la); samples of P-1 and P-2 gave no E P R signal.

972

B . E . DAVYDOVe$ al.

A

b

8.5oe

8.5oe

V FIa. 1. E P R spectra of the following condensation products: a--paraphenylenediamine (PPDA) with glyoxal; b--PPDA with terephthalaldehyde after thermal treatment. -8"0

-11"0

-12.0

I

I

L

2.3

2"5

2.7

~

=

2.,.,° I03/T"K

FIG. 2. Electrical conductivity as a function of the temperature: /--product of the condensation of paraphenylenediamine (PPDA) with diacetyl; 2-product of the condensation of PPDA with terephthalaldehyde; 3--product of the condensation of PPDA with glyoxal; 4--product of the condensation of PPDA with glyoxal subjected to thermal treatment for 4 hours at 300 °. T h e d e p e n d e n c e on t h e electrical c o n d u c t i v i t y o f P - l - P - 3 on t h e t e m p e r a t u r e is s h o w n in Fig. 2. T h e t e m p e r a t u r e d e p e n d e n c e o f the electrical c o n d u c t i v i t y o f t h e s e m a t e r i a l s o b e y s t h e equation: a . = (TO £ - - ' I E / 2 k T

T h e v a l u e s o f AE, ao, a n d a~o for P - l - P - 3 are g i v e n in T a b l e 2.

Preparation and properties of some I)oly-(Schiff's bases)

973

T A B L E 2. E L E C T R O P H Y S I C A L P R O P E R T I E S OF T H E P O L Y - ( S C H I F F ' S BASES)

Substance

ziE, eV

a0, ~-1"cm-1

a20, ~-l"cm-1

P-1 P-2 P-3 P-4*

2.40 2.43 1-96 0.82 1.06

12×10 a 1.80 × 105 2.0 × 102 3.2 ×10 -4 1-4 × 1 0 -2

1-1 ×10 -Is 1.81 × 10 -le 2.0 ×10 -15 2.5 x 1 0 - n 9 . 1 0 -~2

* P - 4 - p r o d u c t of the thermal treatment of sample P-3.

The Schiff's bases obtained were subjected to thermal treatment. On heating f o r 4 h o u r s a t 250 °, P - l - P - 3 l o s t 12.87, 3.56, a n d 2 0 . 9 % o f t h e i r w e i g h t a n d a t 300 ° f o r t h e s a m e t i m e 17.20, 5.16, a n d 2 7 . 4 0 % o f t h e i r w e i g h t , r e s p e c t i v e l y . After the thermal treatment of samples P-1 and P-2, a single sharp EPR s i g n a l a p p e a r e d ( F i g . lb). I n a l l p r o b a b i l i t y t h i s is c o n n e c t e d w i t h t h e f a c t t h a t o n thermal treatment, in addition to the degradation of the substance, further polycondensation also occurs, leading to a lengthening of the chain of polyconjugation. Figure 2 gives the dependence of the electrical conductivity on the temperature ( c u r v e 4) f o r t h e t h e r m a l l y t r e a t e d p r o d u c t o f t h e p o l y c o n d e n s a t i o n o f P P D A w i t h g l y o x a ] (P-4). T h e c u r v e o f l o g a = f ( 1 / T ) h a s a b r e a k . T h e e n e r g i e s o f ~ c t i r a t i o n , q0 a n d a20 g i v e n i n T a b l e 2 w e r e c a l c u l a t e d f o r t h e l i u e a r s e c t i o n s .

EXPERIMENTAL

Polycondensatio~ of glyoxal with PPDA. A reactor fitted with a mechanical stirrer, reflux condenser, and dropping funnel was charged with 0.87 g (0.015 mole) of glyoxal in 150 ml of acetic acid and then 2.16 g (0-015 mole) of P P D A was added. Condensation was carried out at 85 ° for 8 hours. Then t~e solution was cooled and the black precipitate which had separated was filtered off, washed with hot water to neutrality a n d then with acetone, and was dried at 60 ° in vacuum. Yield of product 1.664 g or 64.4% of theoretical. Polycondensation of PPDA with terephthalaldehyde. A reactor was charged with 350 ml of anhydrous benzene and this was heated to the boil. To the boiling benzene was added 1.44 g (0.01 mole) of P P D A and then, over an hour, 1.34 g (0.01 mole) of terephthalaldehyde dissolved in 150ml of benzene was added in drops. Simultaneously with the addition of the aldehyde, an azeotropic mixture of benzene and water was distilled off. After the addition of the aldehyde, the mixture was heated for a further 20 hours. The yellow precipitate which had separated was filtered off, washed repeatedly with hot toluene, and dried in vacuum at 60 °. The yield of product was 2.033 g or 98.4% of theoretical. The product of the polycondensation of P P D A with diacetyl was obtained in the same way. CONCLUSIONS (1) S c h i f f ' s b a s e s w i t h c o n j u g a t e d b o n d s a n d a h e t e r o a t o m i n t h e m a i n c h a i n , not previously reported, have been obtained. (2) S o m e e l e c t r o p h y s i c a l p r o p e r t i e s o f t h e s e s u b s t a n c e s h a v e b e e n s t u d i e d .

974

YE. B. TROSTYANSKAYA¢~al.

It has been established that the temperature dependence of the electrical conductivity obeys the law a = a o e -zE/2~T. Translated by B. J. HAZZARD

REFERENCES 1. V. A. KARGIN, A. V. TOPCHIEV, B. A. KRENTSEL' et al., Zh. vses. khim. obsheh, im. Mendeleyeva 5: 507, 1960 2. A. A. BERLIN, Khim. i tekh. polimerov, No. 7-8, 139, 1960 3. F. H. WINSLAW, W. A. BAKER and W. A. YAGER, J. Amer. Chem. Soe. 77: 4751, 1955 4. A. EPSTEIN and B. S. WILDI, J. Chem. Phys. 32: 324, 1960. 5. A. V. TOPCHIEV, M. A. GEIDERIKH, B. E. DAVYDOV et al., Dokl. Akad. Nauk SSSR 128: 312, 1959 6. N. N. SEMENOV, Osnovnyye problemy khimicheskoi kinetiki, Doklad na V I I I , Mendeleyevskom s'yezde. (Fundamental Problems of Chemical Kinetics, Paper at the 8th Mendeleyev Conference.) Izd. Akad. Nauk SSSR, 1960 7. M. A. GEIDERIKH, B. E. DAVYDOV, B. A. KRENTSEL' et al., Mezhdunarodnyi simpozium po makromolekulyarnoi khimii. (International Symposium on Maeromoleeular Chemistry.) Moscow, Section I I I , p. 85, June 1960 8. N. N. SEMENOV, Khim. i tekh. polimerov, No. 7-8, 196, 1960 9. E. BAYER, Chem. Ber. 90: 2785, 1957 10. C. MARVEL, N. TARK()Y, g. Amer. Chem. Soe. 79: 6000, 1957 11. H. KRASSIG and G. GREBER, Makromolek. Chem. 17: 131, 1956

INSOLUBLE QUATERNARY PHOSPHONIUM POLYMERS* Y E . B . TROSTYANSKAYA, S. B . MAKAROVA a n d I . P . LOSEV D.I.

Mendeleyev Moscow Chemical a n d Technological Institute (Received 31 J u l y 1961)

A T T H E present time, a large number of investigations has been devoted to the synthesis of polyelectrolytes consisting of quaternary ammonium compounds and to the study of their properties [1, 2]. The resulting highly basic polyelectrolytes, both the soluble and, particularly, the insoluble ones, have found wide practical application. Methods of obtaining other polymeric onium compounds (sulphonium and phosphonium compounds) and, all the more, their properties are very sparingly reflected in the literature [3-6]. We have carried out an investigation to establish the optimum conditions for obtaining insoluble polymeric phosphonium corn-

* Vysokomol. soyed. 5: No. 3, 325-329, 1963.