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

• Published in: Crystal growth & design Vol. 13; no. 3; pp. 1360 - 1366
• Main Authors: Wu, Songwei, Gao, Jie, Emge, Thomas J, Rogers, Michael A
• Format: Journal Article
• Language: English
• Published: Washington,DC American Chemical Society 06.03.2013
• Subjects: Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Methods of nanofabrication; Organic compounds; Physics; Self-assembly; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Thiols; Ketones; Organic solvents; Alkanes; Nanostructures; Aldehydes; Nanometer scale; Hexagonal lattices; Self-assembly; Triclinic lattices; Lamellar structure; Supramolecular structure; Nitriles
• ISSN: 1528-7483; 1528-7505
• DOI: 10.1021/cg400124e

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 %.