Organogels and its Applications

Low molecular weight organogelators (LMOGs) are emerging as attractive materials for cosmetics, sensors, template materials, drug delivery agents, biomedical applications, tissue engineering, food processing, phase selective gelation, dye sensitized solar cells and soft optical devices.
For a long time, molecular gels have been employed in relatively low-cost bulk applications, such as in lubricants, grease, and personal care products. However, with a clear understanding of nanoscale self-assembly processes, gelators can be designed to generate or exhibit unique forms of biological activity or materials behavior.
Regenerative medicine and tissue engineering using molecular gels as nanostructured scaffolds for the regrowth of nerve cells has been demonstrated in vivo, and the prospect of using self-assembled fibers as one-dimensional conductors in gel materials has captured much interest in the field of nanoelectronics.
Organogelators are molecules capable of self-assembling into long, fibrous structures of nanosized diameters through highly specific noncovalent interactions such as hydrogen bonding, van der Waals, -stacking, electrostatic, and charge-transfer interactions. Noncovalent cross-links between the nanofibers and/or mechanical entanglements create a three-dimensional network, which entraps the solvent inside the interstices leading to gelation and loss of fluidity of the system. The basic structural requirement for a molecule to exhibit gelation properties is its self-complementarity and capability of undergoing unidirectional self-assembly into fibrous aggregates instead of dissolution or crystallization. We expect that the control of the supramolecular organization ubiquitous in molecular gels can be triggered by external stimuli, since weak intermolecular interactions are sensitive to temperature, magnetic fields, electric fields, pH and light.

Among the LMOGs, those capable of gelating one solvent preferentially over the other in a given two-phase mixture are termed as phase selective organogelators (PSOGs). These small molecules self-assemble into fibers in liquid and form networks above the minimum gelation concentration (MGC) and thus convert the liquid to a gel. Despite a large number of LMOGs reported in the literature, PSOGs are still rare. PSOGs are becoming extremely relevant for water purification and the recovery of oil from water, especially when the World has seen several devastations of the marine ecology due the spillage of oil in recent times and the existing materials proved to be incapable of handling the situation well. There is a great need to develop techniques for managing this type of pollution.