Variable temperature NMR of organogelators: the intensities of a single sample describe the full phase diagram. Issue 14 (27th March 2018)

• Record Type: Journal Article
• Authors: Christ, Elliot; Collin, Dominique; Lamps, Jean-Philippe; Mésini, Philippe J.
• Is Part Of: Physical chemistry chemical physics. Volume 20:Issue 14(2018)
• Page Start: 9644
• Page End: 9650
• Publication Date: 2018-03-27
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/c8cp00009c
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : When an organogel is heated gradually, the intensities of its NMR signals as a function of temperature, in a single sample, provide the c – T phase diagram of the gelator/solvent system. Abstract : Organogelators constitute a numerous class of compounds, able to form gels in organic solvents. Their phase diagrams are useful to understand their mechanisms of formation and their stability, but their mapping is often a tedious task. We show that liquid NMR can simplify and quicken the acquisition of phase diagrams. In liquid NMR spectra of organogels, the visible signals of the gelator represent only its soluble fraction. The intensities increase with temperature, until the gel melts. Suitable normalization of these intensities yields the solubility as a function of temperature, which is sufficient to map the phase diagram. We verified it experimentally with three organogelators, chosen because independent authors have previously mapped out their phase diagram by other techniques including DSC and rheology. We show that the curves obtained by NMR superimpose with these diagrams. A variable temperature NMR experiment with a single sample can yield the phase diagram with sensitivity of the order of 0.01 wt%.