Glass Transition Temperatures of Organic Mixtures from Isoprene Epoxydiol-Derived Secondary Organic Aerosol
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Updated: Jul 31, 2025

Production and Measurement of Organic Particulate Matter in a Flow Tube Reactor
Published on: December 15, 2018
Bo Chen1, Jessica A Mirrielees2, Yuzhi Chen3
1Department of Atmospheric Sciences, Texas A&M University, Eller O&M Building, 1204, 3150 TAMU, 797 Lamar Street, College Station, Texas 77843, United States.
Abstract:
The phase states and glass transition temperatures (Tg) of secondary organic aerosol (SOA) particles are important to resolve for understanding the formation, growth, and fate of SOA as well as their cloud formation properties. Currently, there is a limited understanding of how Tg changes with the composition of organic and inorganic components of atmospheric aerosol. Using broadband dielectric spectroscopy, we measured the Tg of organic mixtures containing isoprene epoxydiol (IEPOX)-derived SOA components, including 2-methyltetrols (2-MT), 2-methyltetrol-sulfate (2-MTS), and 3-methyltetrol-sulfate (3-MTS). The results demonstrate that the Tg of mixtures depends on their composition. The Kwei equation, a modified Gordon-Taylor equation with an added quadratic term and a fitting parameter representing strong intermolecular interactions, provides a good fit for the Tg-composition relationship of complex mixtures. By combining Raman spectroscopy with geometry optimization simulations obtained using density functional theory, we demonstrate that the non-linear deviation of Tg as a function of composition may be caused by changes in the extent of hydrogen bonding in the mixture.
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