Vapor pressure mapping of ionic liquids and low-volatility fluids using graded isothermal thermogravimetric analysis

Sudhir Ravula, Nathaniel E. Larm, Mohammad A. Mottaleb, Mark P. Heitz, Gary A. Baker

Research output: Contribution to journalArticlepeer-review

63 Scopus citations


One of the hallmarks of ionic liquids (ILs) and a critical part of their sustainable implementation is their low volatility, although statements in this regard are frequently made in the absence of a critical evaluation. Although it is generally accepted that conventional ILs exhibit significantly reduced vapor pressures relative to common organic solvents, glib statements about ILs having zero volatility can no longer be abided, even if a concrete temperature-dependent vapor pressure, Pvap (T), framework for placement of IL performance has not yet been established. In this communication, Pvap (T) values of 30 illustrative low-volatility fluids—including representative imidazolium-, ammonium-, and pyrrolidinium-based aprotic ILs; examples of protic, polymeric, and di-cationic ILs; as well as deep eutectic solvents (DESs) and glycols—were determined using a simple, convenient, and reproducible isothermal thermogravimetric method. Guided by this “vapor pressure map”, observed trends can be discussed in terms of anion basicity, cation geometry, alkane chain length, hydrogen bonding strength, and van der Waals forces, providing a context for the placement of theoretical and experimental vapor pressures gleaned in future IL and DES studies.

Original languageEnglish
Article number42
Pages (from-to)1-12
Number of pages12
Issue number2
StatePublished - Jun 2019

Bibliographical note

Publisher Copyright:
© 2019 by the authors. Licensee MDPI, Basel, Switzerland.


  • Deep eutectic solvents
  • Ionic liquids
  • Thermogravimetric analysis
  • Vapor pressure

ASJC Scopus subject areas

  • General Chemical Engineering
  • General Engineering
  • General Energy


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