Electropolymerisation of Phenylacetylene on Pt Electrodes with Propylene Carbonate and Acetonitryle as Solvents

Estudio de la Electropolimerización de Fenilacetileno sobre Electrodo de Pt en Disoluciones de Carbonato de Propileno y de Acetonitrilo

 

J. García Cañadas,^a A. Lafuente,^b G. Rodríguez,^b M.L. Marcos,^a J. González Velasco^a,*

 

Universidad Autónoma de Madrid. Facultad de Ciencias. 28049 Madrid. España.

^a) Departamento de Química. ^b) Departamento de Química Orgánica.

 

Received 2 April 2004; accepted in revised form 29 June 2004

 

 

Abstract

The electropolymerization of phenylacetylene on a Pt electrode has been carried out in two different solvents, acetonitryle and propylene carbonate. The kinetic study carried out leads to values in the kinetic parameters which are significantly different in both solvents. The values deduced for na, Z (reaction order with respect to the phenylacetylene concentration) and activation enthalpy and entropy, were 0.75, 1, 25.3 kJ mol^-1 and –87.0 J mol^-1 K^-1, respectively, in acetonitrile, and 0.25, 0.5, 33.6 kJ mol^-1 and –105 J mol^-1 K^-1, when working in propylene carbonate. The discrepancy in the values can be explained as a consequence of the change in the initiation step of the polymerisation induced by the adsorption of the acetonitryle molecules. The product obtained was isolated, purified and characterised to be formed by a polyenic chain with a linear trans structure. The average molar mass of the product was 3095, corresponding to a polymer formed from around 30 units of monomer.

 

Keywords: mechanistic study, electropolymerization, polyphenylacetylene.

 

 

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* Corresponding author. E-mail address: jaime.gonzalez@uam.es.