A novel dialkylurea gelator, 1-methyl-2,4-bis(N'-octadecaneureido)benzene (designated as MBOB) was synthesized, which can turn some organic solvents into organogels at extremely low concentrations (<2 wt%). The H-1 NMR spectra of MBOB in solution (110 degrees C) and in the gel state (30 degrees C) indicate that intermolecular hydrogen bonding is the driving force for the self-assembly of MBOB. In the process of the self-assembly of MBOB, orientation of MBOB aggregates occurs under the influence of external fields, such as a centrifugal force and shearing force fields. The minimum gelation concentrations of MBOB in organic solvents under a centrifugal force field were significantly higher than those in the absence of a centrifugal force field, indicating a significant effect of the external field on the self-assembly of MBOB. Field en-fission scanning electron microscopy (FE-SEM) provided evidence for a significantly phase transition of the MBOB aggregates from an amorphous state in the absence of the external field to an oriented state under conditions of a centrifugal or shearing force during the gelation process. A self-assembled structure of MBOB is proposed based upon an X-ray diffraction (XRD) analysis and a molecular simulation. DSC analysis of the organogels indicates that the phase transition temperature increased from 58.5 degrees C in the absence of the external field to 63.3 degrees C under a centrifugal force field and 62.2 degrees C under a shearing force field. The enthalpy of the phase transition decreased from 3.1 J/g in the absence of an external field to 2.6 J/g under a centrifugal force field and 2.7 J/g under a shearing force field. (C) 2007 Elsevier Inc. All rights reserved.