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https://doi.org/10.5194/egusphere-2026-1577
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2026-1577
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
11 May 2026
| 11 May 2026
Molecular dynamics study on the liquid-liquid contact angle in liquid-liquid phase separated aerosols
Abstract. The contact angle is a key parameter in describing the morphology of liquid-liquid phase separated (LLPS) aerosols. However, existing experimental methods are unable to precisely measure the contact angle at the nanoscale. Here, molecular dynamics (MD) simulations based on Martini force field and OPLS-UA force field are conducted to reveal the effects of temperature, water content, inorganic salt (NaCl) content and surfactant (suberic acid) content on the liquid-liquid contact angle in water-dodecane LLPS aerosols, and the applicability of classical Young’s equation is analyzed. MD simulations show that the contact angle is positively correlated with temperature and water content but is negatively correlated with NaCl content and suberic acid content. The Martini force field generally results in larger contact angles and stronger influence of NaCl than the OPLS-UA force field. Interfacial tensions of gas-water and water-dodecane calculated based on the OPLS-UA force field are closer to the experimental results. At the nanoscale, the contact angle calculated by Young's equation always deviates significantly from MD simulations, necessitating the inclusion of line tension. Furthermore, reliable line tensions for different systems have been obtained and fitted with a quartic polynomial function.
How to cite. Zhang, C., Liu, L., Li, S., Lin, H., Yang, Y., Ma, N., Wang, Y., and Wiedensohler, A.: Molecular dynamics study on the liquid-liquid contact angle in liquid-liquid phase separated aerosols, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2026-1577, 2026.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Status: final response (author comments only)
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
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RC1: 'Comment on egusphere-2026-1577', Mária Lbadaoui-Darvas, 09 Jul 2026
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2026/egusphere-2026-1577/egusphere-2026-1577-RC1-supplement.pdfCitation: https://doi.org/
10.5194/egusphere-2026-1577-RC1 -
RC2: 'Comment on egusphere-2026-1577', Anonymous Referee #1, 11 Jul 2026
This is a thorough review of the manuscript titled: “Molecular dynamics study on the liquid-liquid contact angle in liquid-liquid phase separated aerosol”. I suggest Major revision due to the following reasons:
- The manuscript compares Martini and OPLS-UA, but it never clearly explains:
- Which force field is expected to be more reliable for the present systems?
- Which one should readers trust when the two produce noticeably different contact angles and different NaCl aggregation behavior?
- Are these differences due to coarse-graining, parameterization, or some other physical reason?
- Are there any experimental measurements or previous MD simulations that can quantitatively validate the predicted contact angles, rather than only the interfacial tensions?
- How representative is dodecane of real atmospheric organic aerosols? Would the conclusions remain valid for more oxygenated organic compounds?
- Why was suberic acid chosen instead of more common atmospheric organic acids such as oleic acid or succinic acid?
- Have the authors performed any size-dependence analysis to ensure that the reported contact angles are not artifacts of finite droplet size?
- How was equilibrium verified? Were longer simulations performed to confirm that the contact angle had fully converged?
- Can the authors provide statistical uncertainties or confidence intervals for the calculated contact angles and line tensions?
- Why was a fourth-order polynomial selected? Was this based on physical reasoning or simply because it gave the smallest fitting error?
- Can the authors provide a molecular interpretation of why increasing temperature consistently increases the contact angle?
- Is the NaCl aggregation observed with Martini a physical prediction or a known artifact of the coarse-grained force field?
- At approximately what droplet size does the line-tension correction become negligible so that the classical Young equation becomes valid?
- How sensitive are the calculated contact angles to the fitting procedure and the bin size used to determine the droplet interface?
- Can the authors estimate how much including line-tension corrections would change predictions of aerosol morphology in existing climate or atmospheric chemistry models?
Citation: https://doi.org/10.5194/egusphere-2026-1577-RC2
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Chao Zhang
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
State Key Laboratory of Atmospheric Environment and Extreme Meteorology, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
Leyi Liu
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Shaopeng Li
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Haoyang Lin
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Yang Yang
CORRESPONDING AUTHOR
School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
Nan Ma
Institute for Environmental and Climate Research, College of Environment and Climate, Jinan University, Guangzhou, Guangdong 511443, China
Yueshe Wang
State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an 710049, China
Alfred Wiedensohler
Leibniz Institute for Tropospheric Research, 04318, Leipzig, Germany
Short summary
This study uses computer simulations to reveal how atmospheric particles composed of water and oil-like substances arrange internally. The research reveals that the contact angle between the two liquids depends on temperature, water content, inorganic salt, and surfactant. This internal structure affects sunlight interaction and cloud formation, impacting climate predictions. The work improves our ability to model these complex atmospheric processes accurately.
This study uses computer simulations to reveal how atmospheric particles composed of water and...