Study on the evolution of the properties

of the doped substituted poly-para-phenylene

S. Ayachi1, S. Bergaoui2, A. Haj Saïd2, F. Matoussi2, A. Mabrouk1, B. Zaidi1,

P. Molinié3, M. Ghedira1, K. Alimi1*

1 Laboratoire des Matériaux, Faculté des Sciences de Monastir, 5000 Monastir, Tunisie

2 Laboratoire de Recherche Cinétique-Electrochimique et Electroanalyse, Faculté des Sciences de Monastir,5000 Monastir, Tunisie

3 Institut des Matériaux Jean Rouxel, CNRS-UMR 6502, 2,rue de la Houssinière, BP 32229, 44322 Nantes cedex 03, France

* Corresponding author. E-mail : kamel.alimi@fsm.rnu.tn

Received : 09 May 2002; revised version accepted : 18 February 2003

Abstract

The object of this work is the doping of the substituted poly-para-phenylene. This last named poly-m-methoxy toluene (PMMT), formed by motives of poly-para-phenylene (PPP) except, the methoxy and methyl groups are grafted in 2, 5 positions of the phenyl ring. PMMT polymers was obtained by preparatory electrolysis, two support electrolytes are used: the sulfuric acid (H2SO4) and the tetrafluoroborate of tetraethyl ammonium ((C2H5)4N+BF4- ). The two polymers are chemically doped with iodine and organic acids (CH3SO3H and CF3COOH). The spectroscopy of photoelectron (XPS) analyses show that the doping species are in ionic form. The infra-red absorption (IR) analyses prove the appearance of new absorption bands attributed to the dopants. The optical density (OD) measurements show an increase in the optical gap after doping. The electronic spin resonance (ESR) measurements reveal a clear reduction in the ESR relative intensity signals after doping. XPS, IR, OD and ESR incontestably show a charge transfer (CT) complex formed between two PMMT polymers and dopants. The results of the OD measurements and those of ESR converges towards dedoping of these products rather than doping.

Keywords: PPP; Iodine; Charge transfer; ESR; Mechanism.

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