EPSRC grant to study liquid-liquid phase transitions

EPSRC grant to study liquid-liquid phase transitions

Issued: Thu, 27 Oct 2011 09:24:00 BST

The peculiar behaviour of liquid and supercooled water has been baffling science for at least 236 years and is still seen as a major challenge facing chemistry today. In the 1970s and 1990s, it was suggested that such strange behaviour might be caused by thermodynamic transitions, possibly even a second critical point associated with an amorphous-to-amorphous liquid-liquid phase transition. Unfortunately, this liquid-liquid transition (if it exists) is very difficult to study as it is thought to lie below the homogeneous nucleation temperature in a region known as “no man’s land”.

Theoretical considerations suggest that liquid-liquid transitions should be very common in molecular liquids, however, the only molecular liquid in which such a transition is now well established is triphenyl phosphite. Unfortunately, the effect is only observed when the liquid is deeply supercooled and extremely viscous. This precludes a detailed and definitive study of the phenomenon and has led to considerable controversy.

In the UCP group, we have discovered the presence of a liquid-liquid transition in a few simple organic liquids above their melting point where the viscosity is low. EPSRC funding has now been obtained to study these liquid-liquid transitions by studying dynamics from femtosecond to kiloseconds and structure from molecular to macroscopic scales.

Spinodal decomposition 

EPSRC (EP/J004790/1, EP/J004812/1, and EP/J014478/1), £740k, Liquid–liquid transitions in molecular liquids: from supramolecular structure to phase separation, investigators Prof Klaas Wynne (School of Chemistry, Glasgow University) and Jan Sefcik (Chemical and Process Engineering, Strathclyde)

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