Polar Solvent-Induced Unprecedented Supergelation of (Un)Weathered Crude Oils at Room Temperature.

Use of carrier solvents to assist dissolution of phase-selective organogelators (PSOGs) before application in oil gelation is a common approach for solution-based gelators. Because of the competition in H-bonds by the polar carrier solvent, decreased gelling ability of PSOGs was often observed. That is, while data are available, the previously documented biphasic minimum gelling concentrations (BMGCs) are much larger than the MGCs determined using heating-cooling cycle for the same PSOG against the same oil. In this study, we show that, by minimizing amount of polar carrier solvent used, the gelling ability of PSOGs actually can be enhanced very substantially, rather than being weakened. More specifically, we demonstrate that use of a minute amount of polar carrier solvents of different types (e.g., ethyl acetate, acetone, acetonitrile, and tetrahydrofuran) significantly enhances the gelling ability of seven structurally different organogelators in hydrophobic oil. In particular, with the use of 5 vol % essentially nontoxic ethyl acetate, application of this previously unexplored strategy onto four monopeptide-based PSOGs produces up to 11-fold improvement in biphasic gelling ability toward seven (un)weathered crude oils of widely ranging viscosities. While collectively overcoming many problematic issues (slow gelling action, low gelling ability, or a need to use hot or toxic solvent for dissolution of gelator) associated with PSOGs, this surprisingly simple yet powerful and reliable method produces unprecedented rapid supergelation of crude oil at room temperature, with BMGCs of as low as 0.38 w/v % (e.g., 3.8 g per liter of crude oil) and an averaged reduction in material cost of gelators by 85-97%.