ELLIPSOMETRIC STUDY OF ACRYLONITRILE ELECTROPOLYMERISATION ON NICKEL

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ELLIPSOMETRIC STUDY OF ACRYLONITRILE ELECTROPOLYMERISATION ON NICKEL

Y. Bouizem, F. Chao, M. Costa, A. Tadjeddine

To cite this version:

Y. Bouizem, F. Chao, M. Costa, A. Tadjeddine. ELLIPSOMETRIC STUDY OF ACRYLONI-

TRILE ELECTROPOLYMERISATION ON NICKEL. Journal de Physique Colloques, 1983, 44 (C10),

pp.C10-509-C10-512. �10.1051/jphyscol:198310104�. �jpa-00223464�

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JOURNAL DE PHYSIQUE

Colloque CIO, supplément au n°12, Tome Hh, décembre 1983 page C10-509

ELLIPSOMETRIC STUDY OF ACRYLONITRILE ELECTROPOLYMERISATION ON NICKEL Y. Bouizem*, F. Chao, M. Costa and A. Tadjeddine

Laboratoire d'Eleetroehitnie Inter•faciale, C.N.R.S., 1, Vlaee A. Briand, 9219S Meudon Cedex, France

Résumé - Nous avons étudié par ellipsométrie les étapes initia- les de 1 ' électropolymérisation de 1'acrylonitrile sur cathode de nickel dans les conditions électrochimiques définies par G. LECAYON et al/1/ ; nous résumons ici les résultats spécifi- ques obtenus par l'analyse des mesures optiques, notamment le rôle del'oxyde natif, la croissance des films électropolyméri- sés, l'évolution de leurs propriétés électroniques et l'influence du mode de préparation

Abstract - The initial stages of the electropolymerization of acrylonitrile on a nickel cathode,under the electrochemical conditions defined by LECAYON et al/1/, have been studied by ellipsometry. We describe here the influence of native oxide on the grafting of the monomer, the influence of the prepara- tion conditions on the film structure (homogeneous or not)and, the mode of film conductivity due to free electrons.

PRINCIPLE OF THE METHOD

The polyacrylonitrile film was prepared through cathodic polarization of a nickel electrode in a solution of acrilonitrile and (C„H,-KN

CIO, dissolved in acetonitrile. The optical parameters A and ty are recorded during film growth, by using phase and azimut modula- tion ellipsometry / 2 / . A specially designed gas-tight spectroelec- trochemical cell allows the optical measurements to be carried o u t , in a H-O vapor and 0- free atmosphere, as in glove-box conditions (a more detailed description will be found in a paper to be published) .

EXPERIMENTAL RESULTS

Variations of. the current i, the phase A and the azimut ty as a func- tion of potential, are depicted on Figures 1 and 2. They were recorded with a sweep rate of 5.10" V s~ , without and with monomer.

It can be seen through the optical and electrical responses of the monomer free system, that the electrode is covered with a residual oxide film which is reduced between - 2 . and -2.32 V / A g - A g+.

The current a t E = - 2 . 3 2 V is superposed on the reduction wave of the oxide, showing the existence of two simultaneous electrochemical phenomena at the electrode. In the optical curves a similar shape is found up to -2.32 V, but there is a very different morpho- logy for more cathodic potentials with the appearance of several extrema due to complex phenomena at the electrode.

*Present address : Departement de Physique, I.S.E., Universiti d'Oran Es Senia, Algerie

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:198310104

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C10-512 JOURNAL

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the acrylonitrile depletion o f the s o l u t i o n , in the neighbourhood o f t h e reactional b o u n d a r y , on the existence o f defects i n the film.

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at l a s t , in situ measurements with variable incidence a n g l e s carried out on thick f i l m s showed an important optical anisotropy,the conductivity being highest i n the direction o f the polymer chains.

REFERENCES

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^G. L A C A Y O N , Y. B O U I Z E M , C . L E G R E S S U S , C . R E Y N A U D , C. B O I Z I A U , and C. J U R E T ,

Chem. Phys. Lett. 9 1 (1982) 506.

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^F.CHAO a n d

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C h i m i e P h y s i q u e 78 ( 1 9 0 1 ) 4 1 1 .