Solvent-Induced Polymorphic Nanoscale Transitions for 12-Hydroxyoctadecanoic Acid Molecular Gels

12-Hydroxyoctadecanoic acid (12HSA) molecular gels have been reported to form self-assembled fibrillar network (SAFiNs) in organic solvents. For the first time, different polymorphic forms for 12HSA molecular gels have been reported. 12HSA, in alkanes and thiols, have a hexagonal subcell spacing (∼4.1 Å) and are arranged in a multilamellar fashion with a distance greater than the bimolecular length of 12HSA (∼54 Å). This polymorphic form corresponded to SAFiN with CGC less than 1 wt %. 12HSA, in nitriles, aldehydes, and ketones, have a triclinic parallel subcell (∼4.6, 3.9, and 3.8 Å) and interdigitation of the lamellar structure (38–44 Å). This polymorphic form corresponds to a less effective sphereultic supramolecular crystalline network, which immobilizes solvents at CGC greater than 1.5 wt %.