Communication: Existence and control of liquid polymorphism in methanol under shear
Caroline Desgranges1, Jerome Delhommelle1
1Department of Chemistry, University of North Dakota, 151 Cornell Street Stop 9024, Grand Forks North Dakota 58202, USA.
The Journal of Chemical Physics
|September 24, 2018
Summary
Scientists discovered that methanol under shear can exist in two distinct liquid forms, a phenomenon known as liquid polymorphism. This finding opens new avenues for studying and controlling liquid states under non-equilibrium conditions.
Area of Science:
- Physical Chemistry
- Materials Science
Background:
- The liquid-liquid hypothesis proposes that pure substances can exist in multiple liquid forms (polymorphs).
- Understanding supercooled liquids is crucial, but studying low-temperature liquid forms is challenging due to their instability and tendency to crystallize.
Purpose of the Study:
- To investigate the existence and characteristics of liquid polymorphism in methanol under shear stress.
- To explore the relationship between structural differences and dynamical responses of different liquid forms.
- To identify methods for controlling and stabilizing liquid polymorphism.
Main Methods:
- Utilized a coarse-grained model to simulate methanol behavior.
- Employed molecular simulations to analyze liquid structures and dynamics under shear.
- Constructed a solid-liquid-liquid nonequilibrium phase diagram.
Main Results:
- Demonstrated that methanol under shear can achieve a steady state with two distinct liquid forms.
- Showed that these liquid forms exhibit different responses to applied shear stress.
- Correlated dynamical differences with observed structural variations between the liquid polymorphs.
- Established the existence of liquid polymorphism in systems driven out-of-equilibrium.
Conclusions:
- Confirmed liquid polymorphism in methanol under shear, driven out-of-equilibrium.
- Identified pressure and shear stress as key parameters for triggering liquid-liquid transitions.
- Proposed new strategies for stabilizing and studying liquid polymorphism through nonequilibrium phase diagrams.
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