Thermodynamics, morphology and molecular structure of molecular compounds in trisamide triarylamine organogels and pseudo-organogels.

In this paper, potentially-gelling binary systems are investigated by DSC, X-ray and Electron microscopy in order to assess their gel status and the role of the Hansen solubility parameter. The low molecular weight organogelator is a Triarylamine Trisamide (TATA) while the solvents consist of a series of halogeno-ethanes and of toluene. Temperature-concentration phase diagrams are mapped out from DSC traces. They reveal the existence of one or more TATA/solvent molecular compounds. The X-ray data, that display different diffraction patterns depending on the solvent and the temperature, show the existence of different molecular structures, and thus confirm the outcome of the T-C phase diagram. Tentative molecular organizations are also discussed in light of previous results obtained in the solid state. The morphology by TEM on dilute systems, and TEM on more concentrated systems highlight the degree of physical cross-links, which leads one to regard some systems as pseudo-gels.

Some Remarkable Rheological and Conducting Properties of Hybrid PVC Thermoreversible Gels/Organogels.

We report on investigations into the rheological properties of organogels prepared from triarylamine trisamide (TATA) and oligo phenylene vinylene (OPVOH) molecules in binary organogel gels and in ternary thermoreversible networks with poly vinyl chloride (PVC). In the case of OPVOH, we show that the modulus of the ternary gel is simply the sum of the modulus of each binary gel, corresponding to the so-called Voigt upper limit. In contrast, TATA/PVC ternary gels generally exceed the Voigt upper limit. In an attempt to account for this unexpected outcome, we hypothesized that a de-solvation process might occur in the PVC fibrils that possibly originates in the propensity of TATA molecules to form molecular compounds with the solvent. Finally, the conducting properties of TATA/solvent organogels and TAT/PVC/solvent reversible networks were measured. It was found that they strongly depend on the solvent type but are not significantly altered when PVC is present. Therefore, PVC gels can be made conducive by incorporating TATA fibers.