Origin of Invariant Gel Melting Temperatures in the c-T Phase Diagram of an Organogel

Langmuir. 2016 May 17;32(19):4975-82. doi: 10.1021/acs.langmuir.6b00995. Epub 2016 May 5.

Abstract

Binary c-T phase diagrams of organogelators in solvent are frequently simplified to two domains, gel and sol, even when the melting temperatures display two distinct regimes, an increase with T and a plateau. Herein, the c-T phase diagram of an organogelator in solvent is elucidated by rheology, DSC, optical microscopy, and transmitted light intensity measurements. We evidence a miscibility gap between the organogelator and the solvent above a threshold concentration, cL. In this domain the melting or the formation of the gel becomes a monotectic transformation, which explains why the corresponding temperatures are nonvariant above cL. As shown by further studies by variable temperature FTIR and NMR, different types of H-bonds drive both the liquid-liquid phase separation and the gelation.

Publication types

  • Research Support, Non-U.S. Gov't