1
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Siachouli P, Karadima KS, Mavrantzas VG, Pandis SN. The effect of functional groups on the glass transition temperature of atmospheric organic compounds: a molecular dynamics study. SOFT MATTER 2024; 20:4783-4794. [PMID: 38847330 DOI: 10.1039/d4sm00405a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/21/2024]
Abstract
Organic compounds constitute a substantial part of atmospheric particulate matter not only in terms of mass concentration but also in terms of distinct functional groups. The glass transition temperature provides an indirect way to investigate the phase state of the organic compounds, playing a crucial role in understanding their behavior and influence on aerosol processes. Molecular dynamics (MD) simulations were implemented here to predict the glass transition temperature (Tg) of atmospherically relevant organic compounds as well as the influence of their functional groups and length of their carbon chain. The cooling step used in the simulations was chosen to be neither too low (to supress crystallization) nor too high (to avoid Tg overprediction). According to the MD simulations, the predicted Tg is sensitive to the functional groups as follows: carboxylic acid (-COOH) > hydroxyl (-OH) and (-COOH) > carbonyls (-CO). Increasing the number of carbon atoms leads to higher Tg for the linearly structured compounds. Linear compounds with lower molecular weight were found to exhibit a lower Tg. No clear correlation between O : C and Tg was observed. The architecture of the carbon chain (linear, or branched, or ring) was also found to impact the glass transition temperature. Compounds containing a non-aromatic carbon ring are characterized by a higher Tg compared to linear and branched ones with the same number of carbon atoms.
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Affiliation(s)
- Panagiota Siachouli
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
| | - Katerina S Karadima
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
| | - Vlasis G Mavrantzas
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
- Particle Technology Laboratory, Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland
| | - Spyros N Pandis
- Department of Chemical Engineering, University of Patras, Patras, GR 26504, Greece.
- Institute of Chemical Engineering Sciences (ICE-HT/FORTH), Patras, GR 26504, Greece
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2
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Freedman MA, Huang Q, Pitta KR. Phase Transitions in Organic and Organic/Inorganic Aerosol Particles. Annu Rev Phys Chem 2024; 75:257-281. [PMID: 38382569 DOI: 10.1146/annurev-physchem-083122-115909] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2024]
Abstract
The phase state of aerosol particles can impact numerous atmospheric processes, including new particle growth, heterogeneous chemistry, cloud condensation nucleus formation, and ice nucleation. In this article, the phase transitions of inorganic, organic, and organic/inorganic aerosol particles are discussed, with particular focus on liquid-liquid phase separation (LLPS). The physical chemistry that determines whether LLPS occurs, at what relative humidity it occurs, and the resultant particle morphology is explained using both theoretical and experimental methods. The known impacts of LLPS on aerosol processes in the atmosphere are discussed. Finally, potential evidence for LLPS from field and chamber studies is presented. By understanding the physical chemistry of the phase transitions of aerosol particles, we will acquire a better understanding of aerosol processes, which in turn impact human health and climate.
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Affiliation(s)
- Miriam Arak Freedman
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA; ,
- Department of Meteorology and Atmospheric Science, The Pennsylvania State University, University Park, Pennsylvania, USA
| | - Qishen Huang
- Institute of Chemical Physics, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, Beijing, China;
| | - Kiran R Pitta
- Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, USA; ,
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3
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Mermigkis P, Karadima KS, Pandis SN, Mavrantzas VG. Geometric Analysis of Free and Accessible Volume in Atmospheric Nanoparticles. ACS OMEGA 2023; 8:33481-33492. [PMID: 37744838 PMCID: PMC10515339 DOI: 10.1021/acsomega.3c03293] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 07/19/2023] [Indexed: 09/26/2023]
Abstract
Computer-generated atomistic microstructures of atmospheric nanoparticles are geometrically analyzed using Delaunay tessellation followed by Monte Carlo integration to compute their free and accessible volume. The nanoparticles studied consist of cis-pinonic acid (a biogenic organic aerosol component), inorganic ions (sulfate and ammonium), and water. Results are presented for the free or unoccupied volume in different domains of the nanoparticles and its dependence on relative humidity and organic content. We also compute the accessible volume to small penetrants such as water molecules. Most of the free volume or volume accessible to a penetrant as large as a water molecule is located in the domains occupied by organics. In contrast, regions dominated by inorganics do not have any cavities with sizes larger than 1 Å. Solid inorganic domains inside the particle are practically impermeable to any small molecule, thereby offering practically infinite resistance to diffusion. A guest molecule can find diffusive channels to wander around within the nanoparticle only through the aqueous and organic-rich domains. The largest pores are observed in nanoparticles with high levels of organic mass and low relative humidity. At high relative humidity, the presence of more water molecules reduces the empty space in the inner domains of the nanoparticle, since areas rich in organic molecules (which are the only ones where appreciable pores are found) are pushed to the outer area of the particle. This, however, should not be expected to affect the diffusive process as transport through the aqueous phase inside the particle will be, by default, fast due to its fluid-like nature.
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Affiliation(s)
- Panagiotis
G. Mermigkis
- Department
of Chemical Engineering, University of Patras, GR 26504, Patras, Greece
- Institute
of Chemical Engineering Sciences, FORTH-ICE/HT,
Patras, GR 26504, Patras, Greece
| | - Katerina S. Karadima
- Department
of Chemical Engineering, University of Patras, GR 26504, Patras, Greece
- Institute
of Chemical Engineering Sciences, FORTH-ICE/HT,
Patras, GR 26504, Patras, Greece
| | - Spyros N. Pandis
- Department
of Chemical Engineering, University of Patras, GR 26504, Patras, Greece
- Institute
of Chemical Engineering Sciences, FORTH-ICE/HT,
Patras, GR 26504, Patras, Greece
| | - Vlasis G. Mavrantzas
- Department
of Chemical Engineering, University of Patras, GR 26504, Patras, Greece
- Institute
of Chemical Engineering Sciences, FORTH-ICE/HT,
Patras, GR 26504, Patras, Greece
- Particle
Technology Laboratory, Institute of Energy & Process Engineering,
Department of Mechanical and Process Engineering, ETH Zürich, CH-8092 Zürich, Switzerland
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4
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Ozon M, Tumashevich K, Lin JJ, Prisle NL. Inversion model for extracting chemically resolved depth profiles across liquid interfaces of various configurations from XPS data: PROPHESY. JOURNAL OF SYNCHROTRON RADIATION 2023; 30:941-961. [PMID: 37610342 PMCID: PMC10481271 DOI: 10.1107/s1600577523006124] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 07/12/2023] [Indexed: 08/24/2023]
Abstract
PROPHESY, a technique for the reconstruction of surface-depth profiles from X-ray photoelectron spectroscopy data, is introduced. The inversion methodology is based on a Bayesian framework and primal-dual convex optimization. The acquisition model is developed for several geometries representing different sample types: plane (bulk sample), cylinder (liquid microjet) and sphere (droplet). The methodology is tested and characterized with respect to simulated data as a proof of concept. Possible limitations of the method due to uncertainty in the attenuation length of the photo-emitted electron are illustrated.
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Affiliation(s)
- Matthew Ozon
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
| | | | - Jack J. Lin
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
| | - Nønne L. Prisle
- Center for Atmospheric Research, University of Oulu, PO Box 4500, Finland
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5
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Dommer A, Wauer NA, Angle KJ, Davasam A, Rubio P, Luo M, Morris CK, Prather KA, Grassian VH, Amaro RE. Revealing the Impacts of Chemical Complexity on Submicrometer Sea Spray Aerosol Morphology. ACS CENTRAL SCIENCE 2023; 9:1088-1103. [PMID: 37396863 PMCID: PMC10311664 DOI: 10.1021/acscentsci.3c00184] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Indexed: 07/04/2023]
Abstract
Sea spray aerosol (SSA) ejected through bursting bubbles at the ocean surface is a complex mixture of salts and organic species. Submicrometer SSA particles have long atmospheric lifetimes and play a critical role in the climate system. Composition impacts their ability to form marine clouds, yet their cloud-forming potential is difficult to study due to their small size. Here, we use large-scale molecular dynamics (MD) simulations as a "computational microscope" to provide never-before-seen views of 40 nm model aerosol particles and their molecular morphologies. We investigate how increasing chemical complexity impacts the distribution of organic material throughout individual particles for a range of organic constituents with varying chemical properties. Our simulations show that common organic marine surfactants readily partition between both the surface and interior of the aerosol, indicating that nascent SSA may be more heterogeneous than traditional morphological models suggest. We support our computational observations of SSA surface heterogeneity with Brewster angle microscopy on model interfaces. These observations indicate that increased chemical complexity in submicrometer SSA leads to a reduced surface coverage by marine organics, which may facilitate water uptake in the atmosphere. Our work thus establishes large-scale MD simulations as a novel technique for interrogating aerosols at the single-particle level.
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Lbadaoui-Darvas M, Garberoglio G, Karadima KS, Cordeiro MNDS, Nenes A, Takahama S. Molecular simulations of interfacial systems: challenges, applications and future perspectives. MOLECULAR SIMULATION 2021. [DOI: 10.1080/08927022.2021.1980215] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Affiliation(s)
- Mária Lbadaoui-Darvas
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
| | - Giovanni Garberoglio
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas (FBK-ECT*), Trento, Italy
- Trento Institute for Fundamental Physics and Applications (TIFPA-INFN), Trento, Italy
| | - Katerina S. Karadima
- Department of Chemical Engineering, University of Patras, Patras, Greece
- Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas(FORTH-ICE/HT), Patras, Greece
| | | | - Athanasios Nenes
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
- Institute of Chemical Engineering Sciences, Foundation for Research and Technology Hellas(FORTH-ICE/HT), Patras, Greece
| | - Satoshi Takahama
- ENAC/IIE; Swiss Federal Institute of Technology Lausanne (EPFL), Lausanne, Switzerland
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Hantal G, Sega M, Horvai G, Jedlovszky P. Contribution of Different Molecules and Moieties to the Surface Tension in Aqueous Surfactant Solutions. II: Role of the Size and Charge Sign of the Counterions. J Phys Chem B 2021; 125:9005-9018. [PMID: 34319728 DOI: 10.1021/acs.jpcb.1c04216] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Understanding the role of the counterion species in surfactant solutions is a complicated task, made harder by the fact that, experimentally, it is not possible to vary independently bulk and surface quantities. Here, we perform molecular dynamics simulations at constant surface coverage of the liquid/vapor interface of lithium, sodium, potassium, rubidium, and cesium dodecyl sulfate aqueous solutions. We investigate the effect of counterion type and charge sign on the surface tension of the solution, analyzing the contribution of different species and moieties to the lateral pressure profile. The observed trends are qualitatively compatible with the Hofmeister series, with the notable exception of sodium. We point out a possible shortcoming of what is at the moment, in our experience, the most realistic nonpolarizable force field (CHARMM36) that includes the parametrization for the whole series of alkali counterions. In the artificial system where the counterion and surfactant charges are inverted in sign, the counterions become considerably harder. This charge inversion changes considerably the surface tension contributions of the counterions, surfactant headgroups, and water molecules, stressing the key role of the hardness of the counterions in this respect. However, the hydration free energy gain of the counterions, occurring upon charge inversion, is compensated by the concomitant free energy loss of the headgroups and water molecules, leading to a negligible change in the surface tension of the entire system.
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Affiliation(s)
- György Hantal
- Institute of Physics and Materials Science, University of Natural Resources and Life Sciences, Peter Jordan Straße 82, A-1190 Vienna, Austria.,Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary
| | - Marcello Sega
- Forschungszentrum Jülich GmbH, Helmholtz Institute Erlangen-Nürnberg for Renewable Energy (IEK-11),Fürther Straße 248, D-90429 Nürnberg, Germany
| | - George Horvai
- Department of Inorganic and Analytical Chemistry, Budapest University of Technology and Economics, Szt. Gellért tér 4, H-1111 Budapest, Hungary
| | - Pál Jedlovszky
- Department of Chemistry, Eszterházy Károly University, Leányka utca 6, H-3300 Eger, Hungary
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8
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Roston D. Molecular dynamics simulations demonstrate that non-ideal mixing dominates subsaturation organic aerosol hygroscopicity. Phys Chem Chem Phys 2021; 23:9218-9227. [PMID: 33885092 DOI: 10.1039/d1cp00245g] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The microscopic properties that determine hygroscopic behavior are complex. The importance of hygroscopicity to many areas, and particularly atmospheric chemistry, in terms of aerosol growth and cloud nucleation, mandate the need for robust models to understand this behavior. Toward this end, we have employed molecular dynamics simulations to calculate hygroscopicity from atomistic models using free energy perturbation. We find that currently available force fields may not be well-suited to modeling the extreme environments of aerosol particles. Nonetheless, the results illuminate some shortcomings in our current understanding of hygroscopic growth and cloud nucleation. The most widely used model of hygroscopicity, κ-Köhler Theory (κKT), breaks down in the case of deviations from ideal solution behavior and empirical adjustments within the simplified framework cannot account for non-ideal behavior. A revised model that incorporates non-ideal mixing rescues the general framework of κKT and allows us to understand our simulation results as well as the behavior of atmospheric aerosols over the full range of humidity. The revised model shows that non-ideal mixing dominates hygroscopic growth at subsaturation humidity. Thus, a model based on ideal mixing will fail to predict subsaturation growth from cloud condensation nucleus (CCN) activation or vice versa; a single parameter model for hygroscopicity will generally be insufficient to extrapolate across wide ranges of humidity. We argue that in many cases, when data are limited to subsaturation humidity, an empirical model for non-ideal mixing may be more successful than one for ideal mixing.
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Affiliation(s)
- Daniel Roston
- Department of Chemistry and Biochemistry, University of California-San Diego, La Jolla, CA 92093, USA.
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9
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Keshavarz F, Kurtén T, Vehkamäki H, Kangasluoma J. Seed-Adsorbate Interactions as the Key of Heterogeneous Butanol and Diethylene Glycol Nucleation on Ammonium Bisulfate and Tetramethylammonium Bromide. J Phys Chem A 2020; 124:10527-10539. [PMID: 33267578 DOI: 10.1021/acs.jpca.0c08373] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Condensation particle counter (CPC) instruments are commonly used to detect atmospheric nanoparticles. They operate on the basis of condensing an organic working fluid on the nanoparticle seeds to grow the particles to a detectable size, and at the size of few nanometers, their efficiency depends on how well the working fluid interacts with the seeds under the measurement conditions. This study models the first steps of heterogeneous nucleation of two working fluids commonly used in CPCs (diethylene glycol (DEG) and n-butanol) onto two positively charged seeds, ammonium bisulfate and tetramethylammonium bromide. The nucleation process is modeled on a molecular level using a combination of systematic configurational sampling and density functional theory (DFT). We take into account the conformational flexibility of DEG and n-butanol and determine the key factors that can improve the efficiency of nanoparticle measurements by CPCs. The results show that hydrogen bonding between the seed and the working fluid molecules is central to the adsorption of the first DEG/n-butanol molecules onto the seeds. However, intermolecular hydrogen bonding between the adsorbed molecules can also enhance the nucleation process for the weakly adsorbing vapor molecules. Accordingly, the heterogeneous nucleation probability is higher for working fluid-nanoparticle combinations with a higher potential for hydrogen bonding; in this case, DEG and ammonium bisulfate. Moreover, conformational analysis and methodology evaluations indicate that the consideration of adsorbate conformers and step-wise addition of the vapor molecules to the seeds is not essential for qualitative modeling of heterogeneous nucleation systems, at least for systems where the adsorbate and seed chemical properties are clearly different. This is the first molecular-level modeling study reporting detailed chemical reasons for experimentally observed seed and working fluid preferences in CPCs and reproducing the experimental observations. Our presented approach can be likely used for predicting preferences in similar nucleating systems.
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Affiliation(s)
- Fatemeh Keshavarz
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
| | - Theo Kurtén
- Department of Chemistry, Faculty of Science, University of Helsinki, FI-00014 Helsinki, Finland
| | - Hanna Vehkamäki
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland
| | - Juha Kangasluoma
- Institute for Atmospheric and Earth System Research/Physics, Faculty of Science, University of Helsinki, P.O. Box 64, 00014 Helsinki, Finland.,Aerosol and Haze Laboratory, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, 100029 Beijing, China
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10
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Sou T, Bergström CAS. Contemporary Formulation Development for Inhaled Pharmaceuticals. J Pharm Sci 2020; 110:66-86. [PMID: 32916138 DOI: 10.1016/j.xphs.2020.09.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Revised: 09/02/2020] [Accepted: 09/03/2020] [Indexed: 12/22/2022]
Abstract
Pulmonary delivery has gained increased interests over the past few decades. For respiratory conditions, targeted drug delivery directly to the site of action can achieve a high local concentration for efficacy with reduced systemic exposure and adverse effects. For systemic conditions, the unique physiology of the lung evolutionarily designed for rapid gaseous exchange presents an entry route for systemic drug delivery. Although the development of inhaled formulations has come a long way over the last few decades, many aspects of it remain to be elucidated. In particular, a reliable and well-understood method for in vitro-in vivo correlations remains to be established. With the rapid and ongoing advancement of technology, there is much potential to better utilise computational methods including different types of modelling and simulation approaches to support inhaled formulation development. This review intends to provide an introduction on some fundamental concepts in pulmonary drug delivery and inhaled formulation development followed by discussions on some challenges and opportunities in the translation of inhaled pharmaceuticals from preclinical studies to clinical development. The review concludes with some recent advancements in modelling and simulation approaches that could play an increasingly important role in modern formulation development of inhaled pharmaceuticals.
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Affiliation(s)
- Tomás Sou
- Drug Delivery, Department of Pharmacy, Uppsala University, Uppsala, Sweden; Pharmacometrics, Department of Pharmacy, Uppsala University, Uppsala, Sweden.
| | - Christel A S Bergström
- Drug Delivery, Department of Pharmacy, Uppsala University, Uppsala, Sweden; The Swedish Drug Delivery Center, Department of Pharmacy, Uppsala University, Uppsala, Sweden
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11
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Sabaghian S, Yazdian F, Rasekh B, Shekarriz M, Mansouri N. Investigating the effect of starch/Fe 3O 4 nanoparticles on biodesulfurization using molecular dynamic simulation. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2020; 27:1667-1676. [PMID: 31755060 DOI: 10.1007/s11356-019-06453-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Accepted: 09/06/2019] [Indexed: 06/10/2023]
Abstract
The application of dibenzothiophene (DBT) as a source of energy leads to air pollution. The key solution to overcome this drawback is desulfurization. Magnetic nanoparticles have shown an excellent performance in the desulfurization of dibenzothiophene. In this study, molecular dynamic (MD) simulation was considered for the first time to gain insight about the molecule interactions in the biodesulfurization (BDS) process of DBT using Rhodococcus erythropolis IGTS8, in the presence and absence of starch/magnetic nanoparticles. According to the MD simulation results, the density of the system in the presence of starch/Fe3O4 was ascending while in the absence of these nanoparticles, the density was descending. Starch/magnetic nanoparticles caused more rapid equilibrium state in the biodesulfurization process. The energy diagram showed that magnetic nanoparticles decrease the energy fluctuation and increase the difference of non-bounding energy and potential energy (8 times) compared to (BDS) without nanoparticle, which reflects higher bounded energy in the system using starch/magnetic nanoparticles. The height of RDF peak in the presence of starch/Fe3O4 was 4 times more than the RDF peak in the absence of nanoparticle. In addition, the nanoparticles decreased the fluctuations around optimal temperature in BDS up to 5% compared to other state.
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Affiliation(s)
- Soltan Sabaghian
- Department of Environmental Science, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran
| | - Fatemeh Yazdian
- Department of Life Science Engineering, Faculty of New Science and Technologies, University of Tehran, Tehran, Iran.
| | - Behnam Rasekh
- Research Institute of Petroleum Industry (RIPT), P.O. Box 1485733111, Tehran, Iran.
| | - Marziyeh Shekarriz
- Chemical, Polymeric and Petrochemical Technology Development Division, Faculty of Downstream Technology Development, Research Institute of Petroleum Industry, Tehran, Iran
| | - Nabiallah Mansouri
- Department of Environmental Engineering, Faculty of Natural Resources and Environment, Science and Research Branch, Islamic Azad University, Tehran, Iran
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12
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Kucinski TM, Dawson JN, Freedman MA. Size-Dependent Liquid-Liquid Phase Separation in Atmospherically Relevant Complex Systems. J Phys Chem Lett 2019; 10:6915-6920. [PMID: 31638813 DOI: 10.1021/acs.jpclett.9b02532] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Physical properties of aerosol particles, such as liquid-liquid phase separation (LLPS), have the potential to impact the climate system. Model systems have been shown to have size-dependent LLPS in the submicron regime; however, these systems are an extreme simplification of ambient aerosol, which can include myriad organic compounds. We expand the studies of LLPS in particles consisting of ammonium sulfate and more complex organic mixtures from multiple organic compounds to α-pinene secondary organic matter (SOM). All systems display a size-dependent morphology, with small particles remaining homogeneous while large particles phase-separate. Surprisingly, three-phase particles were also observed in some of the systems in addition to a new phase state that we have termed channel morphology, which can arise upon efflorescence. The existence of size-dependent LLPS in complex organic mixtures and SOM provides evidence that this is a relevant phenomenon for ambient aerosol and should be considered when modeling atmospheric aerosol.
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Affiliation(s)
- Theresa M Kucinski
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Joseph Nelson Dawson
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16801 , United States
| | - Miriam Arak Freedman
- Department of Chemistry , The Pennsylvania State University , University Park , Pennsylvania 16801 , United States
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13
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Zhang C, Wang Y, Wang H, Yang Y, Li C. Microscopic mechanism of the interaction between water and formic acid-sodium chloride aerosol. POWDER TECHNOL 2019. [DOI: 10.1016/j.powtec.2018.11.105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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14
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Wilson JF, Kroupa M, Kosek J, Soos M. Numerical Study of Soft Colloidal Nanoparticles Interaction in Shear Flow. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:15600-15611. [PMID: 30475624 DOI: 10.1021/acs.langmuir.8b03350] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
The mechanical behavior of nanoparticle assemblies depends on complex particle interactions that are difficult to study experimentally. Depending on the nanoparticle morphology, these interactions could lead to adhesive and elastic-plastic behavior during contact deformation. The aim of this research is to study the effect of contact interactions between polymer nanoparticles and their impact on the macroscopic properties of formed aggregates. For this purpose, the discrete element method (DEM) was used to develop an interaction model combining elastic-plastic deformation and adhesion to study the behavior of spherical polymeric nanoparticles. Initially, a pair of particles interacting in the normal direction was simulated to evaluate the effect of adhesion and plastic deformation in the pull-off force of the contact. Based on these results, the simulations were extended to a dispersed system of nanoparticles, in which multibody interactions become dominant. Considering the aggregation between the nanoparticles induced by a shear flow, we performed an analysis of the number of aggregates and aggregates size in time to characterize the strength of clusters formed during the process. The simulation results showed that the interaction strength upon breakage of the clusters, correlating with the aggregates size, depends on the nanoparticle's softness. In this way, we verified that the type of contact interaction directly influences the macroscopic mechanical response of nanoparticle assemblies. Therefore, our model represents a new way of predicting the mechanical behavior of polymer nanoparticle systems and of optimizing it by adjusting primary particle properties.
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Affiliation(s)
- José Francisco Wilson
- University of Chemistry and Technology Prague, Technicka 5 , 16628 Prague 6 , Czech Republic
| | - Martin Kroupa
- University of Chemistry and Technology Prague, Technicka 5 , 16628 Prague 6 , Czech Republic
| | - Juraj Kosek
- University of Chemistry and Technology Prague, Technicka 5 , 16628 Prague 6 , Czech Republic
| | - Miroslav Soos
- University of Chemistry and Technology Prague, Technicka 5 , 16628 Prague 6 , Czech Republic
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