POLY(PARA PHENYLENE) : SOME PROPERTIES RELATED TO THE SYNTHESIS METHOD

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POLY(PARA PHENYLENE) : SOME PROPERTIES RELATED TO THE SYNTHESIS METHOD

G. Froyer, J. Goblot, J. Guilbert, F. Maurice, Y. Pelous

To cite this version:

G. Froyer, J. Goblot, J. Guilbert, F. Maurice, Y. Pelous. POLY(PARA PHENYLENE) : SOME

PROPERTIES RELATED TO THE SYNTHESIS METHOD. Journal de Physique Colloques, 1983,

44 (C3), pp.C3-745-C3-748. �10.1051/jphyscol:19833147�. �jpa-00222661�

POLY(PARA PHENYLENE) : SOME PROPERTIES RELATED TO THE SYNTHESIS METHOD

G. F r o y e r , J . Y . G o b l o t , J . L . G u i l b e r t , F . Maurice and Y. P e l o u s

Centre National d 'Etudes des Telecommunications, Lannion B-ROC/TIC, B.P. 40, 22301 Lannion Cedex, France

Résumé - Le poly(para phënylène) peut ê t r e obtenu par des méthodes d i f - f é r e n t e s . Dans cet a r t i c l e , nous montrons q u ' i l e x i s t e des d i f f é r e n c e s e n t r e deux matériaux en ce qui concerne l ' a b s o r p t i o n o p t i q u e , l ' a b s o r p t i o n IR, l a c o n d u c t i v i t é continue e t l e dopage avec ASF5. D'après ces r é s u l - t a t s convergents, l a longueur des chaînes du.polymère obtenu par l a méthode de Yamamoto e s t plus f a i b l e que c e l l e du polymère obtenu par c e l l e de Kovacic.

Abstract - Poly(para phenylene) can be obtained by different methods.

In this paper, we show the difference between two materials in terms of optical absorption, IR spectroscopy, D.C. conductivity and ASF5 doping.

According to these converging results, the chains of the polymer obtained by the Yamamoto method are shorter than those of the Kovacic polymer.

Several methods are known to synthesize poly(para phenylenes) which display roughly the same IR spectrum, showing one is dealing with basically the same polymer. Never- theless, a more detailed study, carried out by EPR and NMR, indicates a quite dif- ferent magnetic behavior between linear polyphenylenes and polymers which are likely branched. Now, we want to report on optical properties and doping of these two types of polymer.

SYNTHESIS

We used the conversion o f benzene on treatment w i t h aluminium c h l o r i d e - c u p r i c c h l o - r i d e proposed by Kovacic ( 1 ) . This method involves the loss o f an e l e c t r o n from the IT cloud o f benzene (2) _ -

o — 0

leading to a radical cation which can propagate the polymerization through the fol- lowing equation (3) .

C 6 ^H 6 ⁺ <f^> » C / 7 W * P ° ^

The brown powder obtained a f t e r p u r i f i c a t i o n shows a l a r g e EPR signal which might come from s t r u c t u r a l defects r e s u l t i n g from the r e a c t i o n i t s e l f ( 4 ) . Therefore i t i s l i k e l y branched.

The second method we used t o make poly (para phenylene) i s t h a t described by Yamamoto ( 5 ) . The f i r s t step consists i n the formation of a Grignard reagent from a

dihalobenzene T H F B r B r

Br C,H4 Br >- b 4

Mg Br Mg CgH⁴ B r Br Mg C^gH⁴ Mg Br

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19833147

C3-746 JOURNAL DE PHYSIQUE

The subsequent polycondensation c a t a l y z e d by N i c k e l complexes, such as NiC12 (2,2'- b i p y r i d i n e ) ( 6 ) , gives t h e y e l l o w polymer b e a r i n g a bromine atom on one chain end and a number o f spins two orders o f magnitude lower ( 4 ) i n d i c a t i v e o f t h e quasi absence o f s t r u c t u r a l deyects i n t h e chaSns.

C a t a l y s t

___+ Br(C6H4)nH + n M g Br2 r e f 1 ux

This product y i e l d s by e x t r a c t i o n w i t h h o t toluene a s o l u b l e p a r t (up t o 20 % ) .

RESULTS

-

DISCUSSION

The two products were p u r i f i e d according t o t h e l i t e r a t u r e procedures and t h e i r o p t i c a l p r o p e r t i e s were recorded : we show t h e U-V v i s i b l e absorption spectra i n f i g u r e 1.

F i g u r e 1 :

U-V- v i s i b l e absorption

----

Kovacic p o l y phenylene

-

Yamamoto e x t r a c t e d polymer -

.-

Soluble p a r t o f Yamamoto polymer

The maximum o f t h e a b s o r p t i o n s h i f t s towards h i g h e r energy when going from the

"Kovacic" polymer t o the "Yamamoto". Furthermore i t i s t o be noted t h a t the s o l u b l e p a r t of t h i s l a s t polymer sample shows a maximum c l o s e t o 4.0 eV t h e same value as f o r sexiphenyl oligomer ( 6 ) . I n f i g u r e s 2 and 3 are r e p o r t e d the 600-900 cm-1 IR r e g i o n o f both polymers. The C-H o u t o f plane v i b r a t i o n o f para d i s u b s t i t u t e d poly- phenylenes i s known t o s h i f t toward lower frequencies as t h e chain l e n g t h increases : i t occurs a t 837 cm-1 f o r t e r henyl ( 6 ) , 826 cm-1 f o r quaterpenyl ( 6 ) , 818 cm-I f o r quinquephenyl ( 7 ) and 814 cm-7 f o r sexiphenyl ( 7 ) . I n the Kovacic polymer, i t shows up a t 805.7 cm-1 and a t 806.9 cm-1 f o r the Yamamoto e x t r a c t e d polymer ( r e s o l u t i o n 0.25 cm-l). The s o l u b l e p a r t of t h e Yamamoto p o l y phenylene presents i n i t s I R spectrum a C-H o u t of plane v i b r a t i o n of monosubstituted phenyl r i n g s s p l i t t e d a t 753.6 cm-1 and 760.2 cm-1 : these wavenumbers are c h a r a c t e r i s t i c o f quater henyl and sexiphenyl. Furthermore, one can see i n f i g u r e s 2 and 3 t h a t the 766 cm-P band i s much s t r o n g e r i n t h e Yamamoto e x t r a c t e d polymer than i n the Kovacic one and t h i s band i s r e l a t e d t o the monosubstitution of t h e phenyl r i n g s . These r e s u l t s , U-V v i s i b l e a b s o r p t i o n as w e l l as IR spectroscopy, l e a d t o t h e conclusion o f s h o r t e r polymer chains concerning the Yamamoto polymer as compared t o the Kovacic polymer, the mean value being over 7 phenyl u n i t s , as seen by the r e s u l t s gained on the s o l u b l e p a r t o f t h e former one.

FTIR spectrum of t h e e x t r a c t e d Yamamoto polyphenylene

(600

-

900 cm-I region)

Figure 3 :

FTIR spectrum of t h e Kovacic polyphenyl ene (600

-

900 cm-I region)

This d i f f e r e n c e i n terms o f chain length between t h e two polyphenylene samples i s r e f l e c t e d by t h e DC conductivity behavior shown i n t h e following t a b l e .

"Kovacic"

polymer ( 1 )

"Yamamoto"

polymer (5)

t doping f o r 7 hr under 100 t o r r AsF5 leading t o [C6H4(AsF5)0.26-0.301x f o r both sampl e s .

fJRT p r i s t i n e polymer

< 10-16(ficm)-I

< 1 0 - ~ ~ ( f i c m ) - ~ Activation energy

'DC = f ( T ) 0.9 eV

1.4 eV

~ R T AsF5 doped

'

polymer 270 (Rcm)

4 ( ~ c m ) - '

C3-748 JOURNAL DE PHYSIQUE

For t h e same doping l e v e l t h e Kovacic polyphenylene e x h i b i t s a c o n d u c t i v i t y almost two orders o f magnitude h i g h e r than t h a t o f t h e Yamamoto's. Furthermore, i n the p r i s t i n e polymers t h e a c t i v a t i o n energies o f t h e c o n d u c t i v i t y as a f u n c t i o n o f tem- p e r a t u r e a r e q u i t e d i f f e r e n t : t h i s can be c o r r e l a t e d , i n one way o r the other, w i t h the d i f f e r e n c e between the o p t i c a l gaps o f t h e two samples and as we showed pre- v i o u s l y the Kovacic polymer absorbs a t lower energy. As i t i s w e l l e s t a b l i s h e d t h a t the longer the polymer chain, the narrower the gap, we can i n f e r t h a t the Kovacic polymer has l o n g e r chains than t h e Yamamoto. The r e s u l t s o f the D.C. c o n d u c t i v i t y determination f o l l o w the o p t i c a l data. The a c t u a l Yamamoto method y i e l d s 1 in e a r polymer ( 4 ) having weaker mean c h a i n length,though l o n g chains are present as shown by U-V v i s i b l e a b s o r p t i o n t h r e s h o l d a t 2.8 eV, t h e same value as f o r Kovacic's. This i n d i c a t e s t h a t t h e polymer chain d i s t r i b u t i o n i s l a r g e r i n t h i s case.

REFERENCES

(1) KOVACIC P. and OZIOMEK ^J., Macromol. Synth.

2

(1966)23 (2) KOVACIC P. and KOCH F.W., J. Org. Chem. %(1963)4864

(3) ENGSTROM G.G. and KOVACIC P . , J. Polym. Sci., Polym. Chem. Ed. - 15(1977)2453 ( 4 ) ^{FROYER G.,} MAURICE F., BERNIER P. and MAC ANDREW P., Polymer 23(1982)1103 (5) YAMAMOTO T. and YAMAMOTO A., Chem. L e t t .

1977,

353

(6) GOBLOT J.Y., GUILBERT J.L. and MAURICE F., C.N.E.T. Technical r e p o r t NT/LAB/ROC/62

-

August 1982

(7) JOZEFOWICZ M., B u l i . Soc. Chim. de France, Memoire n o 328 (1963)2036