Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material

Petters, M. D.; Kasparoǧlu, Sabin

doi:10.1038/s41598-020-71490-0

Cited by 23 publications

(19 citation statements)

References 120 publications

(200 reference statements)

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“…The increase in viscosity and phase transformation to a rigid gel in ternary systems with divalent ions were also recently observed, and the effects of supramolecular ion–molecule interactions on phase state of mixed organic–inorganic aerosols may need to be considered in aerosol models . Decreases in viscosity for particles less than 100 nm in diameter were recently predicted, and the effects of particle size on aerosol phase transitions also warrant further investigations. − A very recent study reported that even three phases can occur for complex mixtures of primary OA, SOA, and inorganics . These aspects on complex particle morphology and mixing state warrant further investigations in future studies.…”

Section: Discussionmentioning

confidence: 90%

Diurnal and Seasonal Variations in the Phase State of Secondary Organic Aerosol Material over the Contiguous US Simulated in CMAQ

Carlton

Shiraiwa

2021

ACS Earth Space Chem.

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Secondary organic aerosol (SOA) accounts for a substantial portion of atmospheric particulate matter. Phase state plays an important role in the formation and evolution of SOA, while current air quality models usually assume that SOA particles are homogeneous and well-mixed liquids. In this study, we simulate glass transition temperature (T g) and particle viscosity of SOA based on organic molecular composition over the contiguous US in 2016 using the Community Multiscale Air Quality (CMAQ) model. Simulations show that oligomers from anthropogenic and biogenic SOA and acid-catalyzed isoprene SOA are large contributors to T g of dry SOA, and the dominant species that regulates the dry T g variation is dependent on location and season. At the surface, the T g of dry SOA is higher in the western than in the eastern US, which is due to higher mass fractions of accretion products in the western US. Taking into account the water uptake by SOA, the estimated SOA viscosity shows a prominent geospatial gradient, which is nearly a mirror image of relative humidity. SOA viscosity exhibits a strong diel cycle, and the phase state tends to be more viscous in daytime. The seasonal variations in SOA viscosity are substantially smaller than the diurnal variations. Simulations for four diverse field sites show that T g and SOA viscosity exhibit significant vertical variations that increase with the altitude. SOA in winter undergoes glass transition at lower altitude (∼3 km) than the other three seasons, and SOA occurs as a non-liquid phase at lower altitude at night than during the daytime. This suggests that chemical transport models may need to consider the bulk diffusion limitations in partitioning into viscous SOA in dry western areas of US and aloft in the humid eastern US as well as dry periods during the day to accurately predict SOA formation, size distribution dynamics, and subsequent impacts.

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Section: Discussionmentioning

confidence: 90%

Diurnal and Seasonal Variations in the Phase State of Secondary Organic Aerosol Material over the Contiguous US Simulated in CMAQ

Carlton

Shiraiwa

2021

ACS Earth Space Chem.

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“…In this work, we were unable to model the size-dependent D b while reconciling both the mass and size distribution measurements. Future work, informed by more recent studies, , should aim to study this aspect in more detail.…”

Section: Resultsmentioning

confidence: 99%

Particle Size Distribution Dynamics Can Help Constrain the Phase State of Secondary Organic Aerosol

Akherati

Nah

et al. 2021

Environ. Sci. Technol.

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Particle phase state is a property of atmospheric aerosols that has important implications for the formation, evolution, and gas/particle partitioning of secondary organic aerosol (SOA). In this work, we use a size-resolved chemistry and microphysics model (Statistical Oxidation Model coupled to the TwO Moment Aerosol Sectional (SOM-TOMAS)), updated to include an explicit treatment of particle phase state, to constrain the bulk diffusion coefficient (D b) of SOA produced from α-pinene ozonolysis. By leveraging data from laboratory experiments performed in the absence of a seed and under dry conditions, we find that the D b for SOA can be constrained ((1–7) × 10–15 cm2 s–1 in these experiments) by simultaneously reproducing the time-varying SOA mass concentrations and the evolution of the particle size distribution. Another version of our model that used the predicted SOA composition to calculate the glass-transition temperature, viscosity, and, ultimately, D b (∼10–15 cm2 s–1) of the SOA was able to reproduce the mass and size distribution measurements when we included oligomer formation (oligomers accounted for about a fifth of the SOA mass). Our work highlights the potential of a size-resolved SOA model to constrain the particle phase state of SOA using historical measurements of the evolution of the particle size distribution.

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“…The DCIC technique has been described extensively in prior publications (Champion et al, 2019;Marsh et al, 2018;Petters, 2016, 2017a;Rothfuss et al, 2019;Petters, 2018;Tandon et al, 2019;Petters et al, 2019). The basic concept is briefly introduced, and then modifications made to enable low-temperature measurements will be described.…”

Section: Viscosity Measurementmentioning

confidence: 99%

Toward closure between predicted and observed particle viscosity over a wide range of temperatures and relative humidity

Kasparoǧlu

Shiraiwa

et al. 2021

Atmos. Chem. Phys.

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Abstract. Atmospheric aerosols can exist in amorphous semi-solid or glassy phase states whose viscosity varies with atmospheric temperature and relative humidity. The temperature and humidity dependence of viscosity has been hypothesized to be predictable from the combination of a water–organic binary mixing rule of the glass transition temperature, a glass-transition-temperature-scaled viscosity fragility parameterization, and a water uptake parameterization. This work presents a closure study between predicted and observed viscosity for sucrose and citric acid. Viscosity and glass transition temperature as a function of water content are compiled from literature data and used to constrain the fragility parameterization. New measurements characterizing viscosity of sub-100 nm particles using the dimer relaxation method are presented. These measurements extend the available data of temperature- and humidity-dependent viscosity to −28 ∘C. Predicted relationships agree well with observations at room temperature and with measured isopleths of constant viscosity at ∼107 Pa s at temperatures warmer than −28 ∘C. Discrepancies at colder temperatures are observed for sucrose particles. Simulations with the kinetic multi-layer model of gas–particle interactions suggest that the observed deviations at colder temperature for sucrose can be attributed to kinetic limitations associated with water uptake at the timescales of the dimer relaxation experiments. Using the available information, updated equilibrium phase-state diagrams (-80∘C<T<40∘C, temperature, and 0%<RH<100%, relative humidity) for sucrose and citric acid are constructed and associated equilibration timescales are identified.

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Predicting the influence of particle size on the glass transition temperature and viscosity of secondary organic material

Cited by 23 publications

References 120 publications

Diurnal and Seasonal Variations in the Phase State of Secondary Organic Aerosol Material over the Contiguous US Simulated in CMAQ

Diurnal and Seasonal Variations in the Phase State of Secondary Organic Aerosol Material over the Contiguous US Simulated in CMAQ

Particle Size Distribution Dynamics Can Help Constrain the Phase State of Secondary Organic Aerosol

Toward closure between predicted and observed particle viscosity over a wide range of temperatures and relative humidity

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