Interfacial Molecular Behavior and Organization of Low-Fluorine Surfactants at the sc-CO2/Water Interface
- 1Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China
- 2Key Lab. of Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China
Abstract
Understanding the molecular organization of surfactants at the sc-CO2/water interface is essential for the rational design of CO2-philic interfacial formulations with reduced fluorine content. In this work, three low-fluorinated anionic surfactants (LF1–LF3) with different hydrophobic-tail architectures were investigated together with a fluorine-free branched co-surfactant (ZBJ) using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. DFT calculations revealed a clear amphiphilic segregation of solvent affinity: the fluorinated tails preferentially interacted with CO2, whereas the sulfonate headgroups exhibited stronger affinity for water. MD simulations showed that the surfactants, initially positioned at the sc-CO2/water interface, underwent interfacial reorganization and orientational ordering, with their fluorinated tails extending into the sc-CO2 phase and their hydrophilic headgroups oriented toward the aqueous phase. Tail branching strongly affected interfacial packing and structural stability; the three-tailed, claw-like LF3 formed the thickest and most thermodynamically stable monolayer, with an interfacial formation energy of −330.30 kJ/mol. In the LF3/ZBJ mixed system, ZBJ occupied packing voids between LF3 molecules, further stabilizing the mixed monolayer and yielding an interfacial formation energy of −342.07 kJ/mol. These results clarify how tail architecture, CO2-philic/hydrophilic partitioning, counterion coordination, and steric complementarity govern the interfacial organization and stabilization of low-fluorine surfactants, providing molecular-level guidance for the rational design of low-fluorine surfactant formulations for sc-CO2/water systems.
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BibTeX
@article{xue2026interfacial,
title = {{Interfacial Molecular Behavior and Organization of Low-Fluorine Surfactants at the sc-CO2/Water Interface}},
author = {Chunlong Xue and Sihan Feng and Shan Gao and Chenkang Zhao and Hongyu Guo and Xiaorong Li and Guanghui Zhao and Dongjun Wang and Yanfeng Liu and Ying Li},
journal = {Molecules (Basel, Switzerland)},
year = {2026},
month = oct,
doi = {10.3390/molecules31193576},
url = {https://europepmc.org/article/PMC/PMC13667284},
note = {CC BY},
}
RIS
TY - JOUR
TI - Interfacial Molecular Behavior and Organization of Low-Fluorine Surfactants at the sc-CO2/Water Interface
AU - Chunlong Xue
AU - Sihan Feng
AU - Shan Gao
AU - Chenkang Zhao
AU - Hongyu Guo
AU - Xiaorong Li
AU - Guanghui Zhao
AU - Dongjun Wang
AU - Yanfeng Liu
AU - Ying Li
PY - 2026
DA - 2026/10/01
JO - Molecules (Basel, Switzerland)
DO - 10.3390/molecules31193576
UR - https://europepmc.org/article/PMC/PMC13667284
AB - Understanding the molecular organization of surfactants at the sc-CO2/water interface is essential for the rational design of CO2-philic interfacial formulations with reduced fluorine content. In this work, three low-fluorinated anionic surfactants (LF1–LF3) with different hydrophobic-tail architectures were investigated together with a fluorine-free branched co-surfactant (ZBJ) using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. DFT calculations revealed a clear amphiphilic segregation of solvent affinity: the fluorinated tails preferentially interacted with CO2, whereas the sulfonate headgroups exhibited stronger affinity for water. MD simulations showed that the surfactants, initially positioned at the sc-CO2/water interface, underwent interfacial reorganization and orientational ordering, with their fluorinated tails extending into the sc-CO2 phase and their hydrophilic headgroups oriented toward the aqueous phase. Tail branching strongly affected interfacial packing and structural stability; the three-tailed, claw-like LF3 formed the thickest and most thermodynamically stable monolayer, with an interfacial formation energy of −330.30 kJ/mol. In the LF3/ZBJ mixed system, ZBJ occupied packing voids between LF3 molecules, further stabilizing the mixed monolayer and yielding an interfacial formation energy of −342.07 kJ/mol. These results clarify how tail architecture, CO2-philic/hydrophilic partitioning, counterion coordination, and steric complementarity govern the interfacial organization and stabilization of low-fluorine surfactants, providing molecular-level guidance for the rational design of low-fluorine surfactant formulations for sc-CO2/water systems.
SN - 1420-3049
ER -