Thermotropic Phase Behavior of Choline Soaps Regina Klein Helen Dutton Olivier Diat Gordon J. T. Tiddy Werner Kunz 10.1021/jp2006292.s001 https://acs.figshare.com/articles/journal_contribution/Thermotropic_Phase_Behavior_of_Choline_Soaps/2664139 Choline carboxylates (ChC<i>m</i> with <i>m</i> = 12−18) are simple biocompatible anionic surfactants with very low Krafft temperatures, possessing a rich aqueous phase behavior. In the present work, we have investigated the thermotropic mesomorphism of anhydrous ChC<i>m</i> salts for <i>m</i> = 12−18. Transition temperatures and enthalpies determined by differential scanning calorimetry reveal that all investigated compounds exhibit three different phases between −20 and 95 °C. The phases were further characterized by optical polarizing microscopy, NMR spin−spin relaxation, and X-ray scattering measurements. The nature of the phases was identified with increasing temperature as crystalline, semicrystalline, and liquid−crystalline lamellar. Even long-chain choline carboxylates (<i>m</i> = 18) were found to melt into a lamellar liquid−crystalline phase below 100 °C. Accordingly, with choline as counterion in simple fatty acid soaps, not only the water solubility is considerably enhanced but also the melting points are substantially reduced, hence facilitating thermotropic mesomorphism at temperatures between 35 and 95 °C. Thus, simple choline soaps with <i>m</i> = 12−18 may be classified as ionic liquids. 2011-04-14 00:00:00 Choline SoapsCholine carboxylates ChCm thermotropic mesomorphism choline phase Thermotropic Phase Behavior lamellar NMR