Viscoelastic Behavior of a Supramolecular Polymeric System Consisting of Tri-3,7-dimethyloctyl cis-1,3,5-cyclohexanetricarboxamide and n-Decane

Abstract

Viscoelastic behavior of a supramolecular polymeric system, so-called an organogel, consisting of tri-3,7-dimethyloctyl cis-1,3,5-cyclohexanetricarboxamide (DO3CH) and n-decane (C10) was examined varying the concentration of DO3CH (c) and temperature ranged from 20 to 50°C. The obtained storage and loss moduli for the system were well described with the sum of two Maxwell models possessing two sets of a relaxation time and strength: τf and Gf, and τs (>τf) and Gs, whereas the viscoelastic behavior of organogels consisting of N, N', N"-tris(3,7-dimethyloctyl)benzene-1,3,5-tricarboxamide (DO3B) and n-alkanes is well described with only one Maxwell model. The value of Gf is proportional to c2 as observed in entangled flexible polymer systems and the organogels of DO3B. On the contrary, the value of Gs is approximately proportional to c1.3 similarly to the behavior predicted for rigid rodlike polymer solutions. The value of τf is essentially independent of c, while that of τs is kept at a constant and is followed by increasing above c = 10 gL−1. The activation energies of both the relaxation times are less than that for the viscosity of C10. Supramolecular polymeric structure bearing 2-type, rigid rodlike and flexible, portions are generated in the system due to intermolecular hydrogen bonding. The fast relaxation mode is attributed to the entanglement release between the flexible portions as observed in the organogels of DO3B, and the other is attributed to rotational relaxation of the rigid rodlike portion.