Rheological properties and structural correlations in molecular organogels

Organogels of 12-hydroxystearic acid (HSA) have been investigated to emphas ize solvent-dependent relationships between rheological properties and nano structures in this class of physical gels. Different length scales are cons idered: macroscopic with optical opacity, rheology, phase diagram data; nan oscopic with small-angle neutron scattering experiments and molecular with H-1 NMR data. HSA networks are shown to be rigid fibrillar networks with ri gid junction zones and behave as elastoplastic materials. Shear elasticitie s, yield stresses, and deformation behaviors appear connected to the crysta llinity of networks through the cross-sectional shapes of fibers. Kinetics of molecular aggregation and flowing properties are also used to compare th ree classes of HSA gels (toluene, dodecane, nitrobenzene). The melting tran sitions as well as the concentration dependence context of molecular nanoma terials.