Rheology Control of Isododecane with Newly Synthesized Organogelators; 3,3,4,4-Benzophenone Tetracarboxamide

Abstract

Rheology control for hydrophobic fluids is frequently needed in a wide range of industrial and commercial applications, such as inks, paints, food, cosmetics, pharmaceutical products, petroleum products, and so on. Recently, the field of hydrophobic-supramolecular polymeric materials including self-assembly technology has grown rapidly over the past decade. One of the methods to obtain a self-assembly structure is to use low-molecular-weight compounds as hydrophobic solvents. A number of such chemical reagents, which can transform low-viscosity organic liquids into gels and/or gel-like substances, have been synthesized as organogelators. For suitable molecular design of organogelators, both self-assembly of molecules into nanofibers via hydrogen bonding and formation of a threedimensional network structure due to van der Waals interaction might be important. Low-molecular-weight organogelators constructed from many aromatic rings have been reported; e.g., with biphenyl structure, bisurea compounds, and so on. Skeleton structures of benzene or cyclohexane with chemical side chains have also been reported as organogelators. Within these compounds, benzene-1,3,5-tricarboxamide is well known as an effective organogelator for various oils, the thickening property of which may be related to the hydrogen bonds of amide groups. Shikata, et al. investigated both the supramolecular structure and dynamics of benzene-1,3,5tricarboxamide in hydrophobic fluid. The hydrogen bonds of three amide group quickly formed a coordinate structure like a polymer molecule, which entangled and showed remarkable viscoelastic property. However, unlike the case in a polymer, relaxation of the entanglement occurred by the rearrangement of two supramolecular structures, following the Phantom Crossing Model. The effects of introducing chirality chains and polymer chains have previously been reported. Webb, et al. and Tong, et al. examined N,N’,N’’,N’’’-1,2,4,5tetra alkyl pyromellitamide. This organogelator showed a similar thickening effect as that of tricarboxamide, in which four amide groups of chemical side chains were expected to increase the intermolecular force. In these above-mentioned studies, the target oils were general organic solvents like Rheology Control of Isododecane with Newly Synthesized Organogelators; 3,3',4,4'-Benzophenone Tetracarboxamide