Determination of surface thermodynamic properties of
polyaniline (in conducting or non-conducting forms)
by using IGC technique at infinite dilution
Tayssir HAMIEH*a,b , Joumana TOUFAILYa,c
a
Laboratoire de Chimie Analytique, Matériaux, Surfaces et Interfaces (CHAMSI)
Faculté des Sciences, Section 1, Université Libanaise, Hadeth, Beyrouth (Liban)
b
Institut de Chimie des Surfaces et Interfaces (ICSI-CNRS), UPR 9096
15, Rue Jean Starcky, B.P. 2488 - 68057, Mulhouse Cedex (France)
c
Laboratoire LACCO – ESIP, 86000, Poitiers, France
Summary
Many studies were devoted in our Laboratory to the determination of physico-chemical and
thermodynamic properties of polymers and/or oxides by using the inverse gas
chromatography (IGC) at infinite dilution. More particularly, we studied the interactions of
solid substrates with some model organic molecules and their acid-base properties, in Lewis
terms, by determining the acidic and basic constants. We were also interested in previous
papers in studying the physico-chemical and electrical properties of conducting polyaniline
(PANI).
We proposed in this paper to study the surface thermodynamic characteristics of both doped
polyaniline (PANI-HEBSA) and the non-conducting form (PANI-EB) using IGC technique
that allowed to obtain the net retention volume Vn and then the dispersive free enthalpy
Gad of n-alkanes adsorbed on PANI and the specific free enthalpy GaSP of adsorption
corresponding to the specific interactions of polar molecules. By plotting GaSP of the polar
molecules as a function of the temperature, we can deduce the specific enthalpy H aSP and
specific entropy S aSP . Knowing H aSP of the various polar molecules, we were able to
determine the acidic constant KA and basic constant KD, the two constants characterising the
solid substrate and a third parameter K reflecting the amphoteric character of the oxide or
polymer according to our new model:
 H   K
DN  K D AN  K .AN .DN
Where DN and AN are respectively the donor and acceptor numbers of electrons of the solid.
SP
a
A
This expression allowed us to describe more precisely some solids (oxides and polymers) and
especially the acid-base properties and specific enthalpy and entropy of adsorption of
polyaniline.
*
Corresponding author, E. mail : tayssir.hamieh@ul.edu.lb or t.hamieh@uha.fr