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Glass Transition Temperatures of Organic Mixtures from Isoprene Epoxydiol-Derived Secondary Organic Aerosol.

Bo ChenJessica A MirrieleesYuzhi ChenTimothy B OnaschZhenfa ZhangAvram GoldJason D SurrattYue ZhangKristen N Collier
Published in: The journal of physical chemistry. A (2023)
The phase states and glass transition temperatures ( T g ) 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 T g changes with the composition of organic and inorganic components of atmospheric aerosol. Using broadband dielectric spectroscopy, we measured the T g 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 T g 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 T g -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 T g as a function of composition may be caused by changes in the extent of hydrogen bonding in the mixture.
Keyphrases
  • water soluble
  • ionic liquid
  • density functional theory
  • raman spectroscopy
  • molecular dynamics
  • high resolution
  • single molecule
  • quantum dots
  • solid state
  • gestational age