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Updated: Oct 4, 2025
07:36
Versatile CO2 Transformations into Complex Products: A One-pot Two-step Strategy
Published on: November 9, 2019
8.1K
A liquid with distinct metastable structures: Supercooled butyronitrile.
Jan P Gabriel1, Erik Thoms1, A Guiseppi-Elie2
1School of Molecular Sciences, Arizona State University, Tempe, Arizona 85287-1604, USA.
The Journal of Chemical Physics
|February 2, 2022
Summary
Dielectric properties of butyronitrile were studied in bulk and vapor-deposited forms. Bulk samples show a higher dielectric constant, suggesting cluster formation influencing molecular glass behavior.
Area of Science:
- Materials Science
- Physical Chemistry
- Condensed Matter Physics
Background:
- Molecular glasses exhibit complex dielectric relaxation behaviors.
- Butyronitrile is a model molecular glass former.
- Previous studies on butyronitrile's dielectric properties may not capture the full picture.
Purpose of the Study:
- To re-examine the dielectric relaxation behavior of butyronitrile.
- To compare dielectric properties of bulk and vapor-deposited samples.
- To understand the influence of sample preparation on molecular glass dynamics.
Main Methods:
- Dielectric spectroscopy was performed on bulk butyronitrile cooled from the melt.
- Dielectric measurements were conducted on butyronitrile samples prepared by physical vapor deposition.
- Varying deposition temperature and rate for vapor-deposited samples.
Main Results:
- Bulk liquid butyronitrile exhibits a significantly higher dielectric constant (εs = 63) near its glass transition temperature (Tg = 97 K).
- Vapor-deposited samples show a range of dielectric constants (4.5–63) depending on preparation conditions.
- Low dielectric constant values in vapor-deposited samples persist for extended periods, with relaxation times around 0.1 s.
Conclusions:
- The formation of long-lived, non-crystalline clusters with anti-parallel dipole orientation explains the observed dielectric behavior.
- These clusters persist above the glass transition temperature, coexisting with the equilibrium polar liquid fraction.
- Sample preparation methods critically influence the dielectric response and structure of molecular glasses like butyronitrile.
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