Viscoelastic Behavior of Supramolecular Polymeric Systems Consisting of N,N‘,N‘‘-Tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide and n-Alkanes

Abstract

Viscoelastic behavior of supramolecular polymeric systems, so-called organogels, consisting of N,N‘,N‘ ‘-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide (DO3B) and n-alkanes (Cn) such as decane (n = 10), dodecane (n = 12), and tetradecane (n = 14) was examined varying the concentration of DO3B (c) with temperature ranging from 20 to 50 °C. It is widely accepted that DO3B forms long columnar supramolecular structure in nonpolar solvents like Cn due to intermolecular hydrogen bonding between amide groups. The obtained storage and loss moduli as functions of frequency for DO3B/Cn were simple and well described with a Maxwell model possessing only one set of a relaxation time (τ) and strength (GN) just like those in aqueous threadlike micellar systems formed by some surfactants. The value of GN is proportional to c2 as observed in fully entangled linear flexible polymer systems. The value of τ slightly decreases with increasing the value of c contrary to the behavior of the polymer systems. The activation energy of τ was determined to be 32 ± 2 kJ mol-1 irrespective of the sort of solvents and was different from those of the viscosity for each solvent. These strongly suggest that columnar, flexible supramolecular polymeric structure is generated in DO3B/Cn and densely entangles each other to show the pronounced viscoelasticity as well as in the polymer systems, whereas a mechanism for entanglement release is not similar to that in the polymer systems, but to that in aqueous threadlike micellar systems.