Thermoreversible gelation of organic liquids by arylcyclohexanol derivatives Synthesis and characterisation of the gels

Abstract

A variety of organic liquids can be immobilised using certain 4-tert-butyl-1-arylcyclohexanol derivatives (BACOl). Only the isomers with axial aryl groups are active as gelling agents. The BACOl–hydrocarbon systems have been characterised with respect to their rheological properties under shear. The gels are viscoelastic solids with high elastic shear moduli (G′≈70350 Pa at C≈2.2 wt.% in dodecane) and high yield stresses (σ≈620 Pa). A 3D network with high cohesive energy and long lifetimes of the related structures is in thermal equilibrium with the surrounding solution. Diffraction experiments have characterised the crystallinity of the gel networks made up of assemblies of bimolecular BACOl associations (d≈14.3 Å). Xerogels exhibit a mesomorphic organisation with a 76 Å repeating unit. Phase diagrams have been determined as a function of the solvent and gelator types and the related thermodynamic parameters were deduced. IR spectroscopy has demonstrated that H-bonding is responsible for the aggregation of the BACOl molecules.