SYNTHESIS AND PROPERTIES OF (CH)x - FILMS PREPARED BY POLYMERIZATION OF BTFM-TCDT

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SYNTHESIS AND PROPERTIES OF (CH)x - FILMS PREPARED BY POLYMERIZATION OF

BTFM-TCDT

G. Leising, F. Stelzer, H. Kahlert

To cite this version:

G. Leising, F. Stelzer, H. Kahlert. SYNTHESIS AND PROPERTIES OF (CH)x - FILMS PREPARED

BY POLYMERIZATION OF BTFM-TCDT. Journal de Physique Colloques, 1983, 44 (C3), pp.C3-

139-C3-142. �10.1051/jphyscol:1983326�. �jpa-00222677�

JOURNAL DE PHYSIQUE

Colloque C3, supplément au n°6, Tome 44, juin 1983 page C3-139

SYNTHESIS AND PROPERTIES OF ( C H ) - FILMS PREPARED BY POLYMERIZATION OF BTFM-TCDT

G. Leising*, F. Stelzer+ and H. Kahlert*

*Institut fur Festkorperphysik, Stoffe der TV Graz, Petersgasse 16, A-8010 Graz, Austria

+Institut fur Chem. Teohnologie Organ, , Stoffe der TU Graz, Petersgasse 16, A-8010 Graz, Austria

Résumé - Des films de (CH) ont été obtenus par une polyméri- sation métathétique avec ouverture de cycle de 7,8 - bis-(tri- fluorométhyle)-tricyclo[4,2,2,0]-deka-3,7,9-triene (BTFM-TCDT).

Des films 100% trans ont été obtenus, ayant une densité bien supérieure à celle des échantillons obtenus avec la technique de Shirakawa. Nous présentons une étude de la morphologie, de la transmission infrarouge, de la conductivité avant et après diverses procédures de dopage, et comparons ces résultats avec les propriétés de films préparés avec la méthode de Shirakawa.

Abstract - (CH)x-films were prepared by a ring-opening meta- thetical polymerization of 7,8- bis-(trifluoromethyl) —tricyclo—

[4,2,2, Oj- deka-3,7, 9-triene (BTFM-TCDT). 100% trans- (CH)x-f ilms v/ere obtained having a density considerably higher than the films prepared by the Shirakawa-technique. We present a study of the morphology by scanning-electron microscopy, of the in- frared transmission, and of the conductivity before and after various doping procedures, and compare these results with pro- perties of (CH)x-films prepared by the Shirakawa-technique.

1 . INTRODUCTION

Samples for the investigation of the properties of (CH)X almost ex- clusively have been prepared in the past by the so called Shirakawa- technique / ] / , Since such samples exhibit a large scattering of even such basic properties as their density, we have been looking for alternative preparation procedures. The work by Edwards and Feast / 2 / was a first important step in this direction. Starting with the same monomer, we used a modification of their method for the preparation of nearly amorphous (CH)x~films with reproducible morphology and a bulk density comparable to that of the fibers of Shirakawa-(CH)x. 2. EXPERIMENTAL

The monomer BTFM-TCDT can be polymerized using a catalyst system like WCI5 and Sn(CH3)4 and then be converted to (CH)X at higher tempera- tures and dynamic vacuum. The reaction mechanism is shown below:

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1983326

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T h i s two-step p r e p a r a t i o n p r o c e d u r e f o l l o w s t h e method f i r s t described by Edwards and F e a s t (2/. For our work we developed a modified p r o - c e d u r e , which p r o c e e d s i n one s t e p from s t a g e 1 ) t o s t a g e 3 ) i n t h e f o l l o w i n g manner:

To c h l o r o b e n z e n e a s t h e s o l v e n t 0.09 m l of a 0.15 molar WCl6 s o l u t i o n and 1 . I 5 m l of a 0.2 molar Sn ( C H ) s o l u t i o n were added and s t i r r e d f o r 5 min a t room t e m p e r a t u r e . ~ i e n t h e s o l v e n t was removed by a p p l y i n g dynamic vacuum r e s u l t i n g i n t h e f o r m a t i o n of a s o l i d l a y e r of a c t i v e c a t a l y s t on t h e w a l l s of t h e v e s s e l . S u b s e q u e n t l y , 0.3 m l

( 3 . 5 mmole) of t h e monomer were i n t r o d u c e d i n t o t h i s v e s s e l . A f t e r h e a t i n g t h i s l i q u i d l a y e r up t o a b o u t I O O ~ C , t h e r e a c t i o n s t a r t e d immediately, forming a s i l v e r y f i l m a t t h e w a l l s and some foam w i t h m e t a l l i c l u s t e r p l u s a c o l o r l e s s l i q u i d a t t h e bottom of t h e v e s s e l . Thus, t h e p o l y m e r i z a t i o n of t h e monomer 1)-2) and t h e s p l i t t i n g o f f t h e 1 , 2 bis-(trifluoromethy1)-benzene 2)+3) t o o k p l a c e a t t h e same t i m e . The f i l m s were d r i e d by pumping o f f t h e a r o m a t i c compound and c l e a n e d by washing them i n t o l u e n e under a p p l i c a t i o n of an u l t r a - s o n i c c l e a n e r . A l l r e a c t i o n s were c a r r i e d o u t under h i g h vacuum o r under p u r e argon atmosphere.

3. RESULTS AND DISCUSSION

The (CH), we o b t a i n e d by t h i s p r e p a r a t i o n p r o c e d u r e was a f l e x i b l e f i l m w i t h m e t a l l i c l u s t e r . The b u l k d e n s i t y h a s a v a l u e of 1.1 g/cm 3 which i s v e r y c l o s e t o t h e f l o t a t i o n d e n s i t y of Shirakawa-(CH), and a b o u t a f a c t o r of t h r e e h i g h e r t h a n t h e d e n s i t y of (CH),-films p r e - p a r e d by t h e Shirakawa-method.

These (CH),-films a p p e a r t o have no f i b r o u s morphology, a s one can s e e from t h e s c a n n i n g - e l e c t r o n m i c r o g r a p h e s i n F i g . 1 . which show a comparison of t h e morphology of t h e s u r f a c e and t h e b u l k f o r o u r m a t e r i a l ( l e f t hand s i d e ) and t h e m a t e r i a l p r e p a r e d by t h e Shirakawa- method ( r i g h t hand s i d e ) . I n v e s ~ i g a t i o n s of t h e s t r u c t u r e of our m a t e r i a l by X-ray d i f f r a c t i o n and HEED show amorphous r i n g s o n l y , which i n d i c a t e a mean s p a c i n g of 1 0

8.

and s m a l l d i f f r a c t i o n a r e a s no p a t t e r n s produced by c r y s t a l l i n e p a r t s of t h e polymer c o u l d be d e t e c t e d . The m o d i f i c a t i o n of t h i s t y p e of

(CH), i s 100% t r a n s , as one c a n see £ram a t y p i c a l IR-spectrum i n F i g . 2 , which e x h i b i t s o n l y t h e f e a t u r e s of t h e t r a n s - i s o m e r and of r e s i d u a l 3 , 2 b i s - ( t r i f luoromethy1)-benzene. A d d i t i o n a l e v i d e n c e f o r t h e p u r e t r a n s - f o r m of o u r samples can b e s e e n i n t h e DSC-spectrum

shown i n F i g . 3 , where t h e c i s - t r a n s i s o m e r i z a t i o n peak between 1 0 0 ~ ~ and 2 0 0 ' ~ i s c o m p l e t e l y a b s e n t .

We have t r i e d d i f f e r e n t doping p r o c e d u r e s t o i n c r e a s e t h e c o n d u c t i v i - t y of o u r ma e r i a l . The c o n d u c t i v i t y of t h e undoped samples i s of t h e o r d e r of 10-'P'fcm-l and t h u s c o n s i d e r a b l y lower t h a n a l l r e p o r t e d v a l u e s f o r trans-(CHIg p r e p a r e d by t h e Shirakawa-technique. Attempts t o dope o u r samples w l t h i o d i n e o r bromine i n t h e vapour phase d i d n o t r e s u l t i n h i g h c o n d u c t i v i t y v a l u e s , presumably because of t h e h i g h d e n s i t y of t h e m a t e r i a l . Applying t h e t e c h n i q u e of doping i n a s o l u t i o n of low dopant corjlcen r a t i o n r e s u l t e d i n maximum c o n d u c t i - v i t y - y a l u l s of a b o u t 200 Q-

' ' n a

1 0 R cm- f o r t h e c a s e of bromine. The v a l u e f o r t h e i o d i n e doped s a ~ p l e s i s comparable t o t h e r e s u l t r e p o r t e d by Rolland e t a 1 . / 3 / f o r o p t i m a l l y i s o m e r i z e d i o d i n e doped trans-(CH), p r e p a r e d by t h e

Shirakawa t e c h n i q u e .

Fig. 3 : SEM-micrographs of the surface [(a) and (cj] and the bulk E(b) and (d)] of samples obtained by the present method L a ) and(b1 and by the Shirakawa method Kc) and (d)].

v (cm-11 TEMPERATURE ( C 1

Fig.2 IR-transmission spectrum Pig. 3. DSC-spectrum of the of the present (CH),-samples. present (CH) ,-samples (- )

and of Shirakawa- (CH)

,

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ACKNOWLEDGEMENT;

The authors are indebted to Dr.

Golob, Dr

Horn, Dr

Jakopic and Ing. Waltinger from the Zentrum fiir Elektronenmikroskopie for assistance in taking the SEM-micrographs and for the diffraction experiments. This work was supported by the Fonds zur Forderung der wissenschaftlichen Porschung under the project nr.

4. REFERENCES

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W.J., Polymer

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ROLLAND M., BERNIER P.r L E F W T S., and ALDISST M.,

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