XPS investigations of acid–base interactions in adhesion. Part 4.—Use of trichloromethane as a molecular probe for the quantitative assessment of polymer basicity

Abstract

Trichloromethane has been used as a molecular probe for the assessment of acid–base properties of polymers in the solid state. It is shown in this paper that when CHCl₃ is sorbed in polymers it undergoes a negative XPS chemical shift as a result of acid–base interactions. Following the FTIR approach of Fowkes, we determined ΔH_AB, the enthalpy of acid–base adduct formation, for the different polymer–CHCl₃ adducts, and found that the XPS binding energy (E_b) of the Cl 2p_3/2 line is linearly related to ΔH_AB. The relationship is of the form –ΔH_AB/kcal mol^–1= 228.8–1.14 E_b/eV.