Solubility and Surface Thermodynamics of Conducting Polymers by Inverse Gas Chromatography, IV: Polypyrrole/Titanium Oxide

Abstract

A wealth of physico-chemical information has been obtained on an insoluble and crystalline polypyrrole/titanium oxide (PPY/TiO2) using the Inverse Gas Chromatography Method (IGC). Twenty-five solvents (test compounds) with different specific interactions were used. PPY/TiO2 was synthesized and characterized by FTIR and DSC methods. The following characteristics of PPY/TiO2 were explored: changes in morphology, the strength of solvent–PPy/TiO2 interactions, dispersive surface energy, percent crystallinity, solvents and PPy/TiO2 solubility parameters, and molar heat of sorption, mixing and evaporation ($$\Delta H_{1}^{s}$$, $$\Delta H_{1}^{\infty }$$, $$\Delta H_{1}^{v}$$). Interaction parameters were corrected to be free from the solvents’ chemical nature. Nonane, propyl acetate, and methyl ethyl ketone showed stronger interactions and a higher affinity to PPy/TiO2; yet, none of these solvents can dissolve PPy/TiO2. IGC showed that PPy/TiO2 has 59.34 mJ/m2 dispersive surface energy at 100 °C and 98% crystalline at 60 °C. Comprehensive solvents and PPy/TiO2 solubility parameters were obtained and comparted with that of soluble and insoluble polymers. Inverse Gas Chromatography (IGC) along with DSC and FTIR methods investigated the morphology, surface energy, degree of crystallinity and the thermodynamics of conducting polypyrrole/TiO2. The solubility parameters were calculated for 27 solvents.