Modulation of the Molecular Structure of Tri-aryl Amine Fibrils in Hybrid Poly[vinyl chloride] Gel/Organogel Systems

Abstract

This paper reports on the thermodynamics through mapping out temperature–concentration phase diagrams and the molecular structure and the morphology of binary organogels prepared with trisamide triarylamine (TATA) in tetrachloroethane and on their ternary thermoreversible hybrid gels formed with polyvinyl chloride (PVC). For low PVC contents, the TATA organogel moiety behaves as in the binary systems, while for higher PVC contents, the thermal behavior is significantly altered with the appearance of a nonvariant event. The molecular structure of the TATA assemblies is compared with that observed in the bulk solid state. Three molecular packings are observed in the bulk, whose crystalline lattices are tentatively derived. Structure I obtained after the crystallization–purification process is seen to transform at higher temperature into structure II. By cooling, structure III is obtained, which transforms reversibly into structure II on heating. The metastability of structure I leads one to contemplate the possible formation of molecular compounds during the crystallization–purification process in the presence of chlorinated solvents, the more so as the crystalline structures in the gels turn out to exhibit high similarities. Finally, the morphology observation reveals that the TATA fibrils and the PVC matrix can be well identified for low PVC contents, while for higher PVC contents, one essentially observes the TATA fibrils