{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T15:54:12Z","timestamp":1791474852770,"version":"4.3.4"},"reference-count":41,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"},{"start":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T00:00:00Z","timestamp":1791417600000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>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\u2013LF3) 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 \u2212330.30 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 \u2212342.07 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.<\/jats:p>","DOI":"10.3390\/molecules31193576","type":"journal-article","created":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T15:16:52Z","timestamp":1791472612000},"page":"3576","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Interfacial Molecular Behavior and Organization of Low-Fluorine Surfactants at the sc-CO2\/Water Interface"],"prefix":"10.3390","volume":"31","author":[{"given":"Chunlong","family":"Xue","sequence":"first","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"conceptualization","vocabulary":"credit"},{"role":"methodology","vocabulary":"credit"},{"role":"software","vocabulary":"credit"},{"role":"writing-original-draft","vocabulary":"credit"},{"role":"investigation","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Sihan","family":"Feng","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Shan","family":"Gao","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Chenkang","family":"Zhao","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Hongyu","family":"Guo","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Xiaorong","family":"Li","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"}]},{"given":"Guanghui","family":"Zhao","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"supervision","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]},{"given":"Dongjun","family":"Wang","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]},{"given":"Yanfeng","family":"Liu","sequence":"additional","affiliation":[{"name":"Daqing Petrochemical Research Center, Petrochemical Research Institute of PetroChina, Daqing 163714, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"project-administration","vocabulary":"credit"},{"role":"funding-acquisition","vocabulary":"credit"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2862-083X","authenticated-orcid":false,"given":"Ying","family":"Li","sequence":"additional","affiliation":[{"name":"Key Lab. of Colloid and Interface Chemistry of State Education Ministry, School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, China"}],"role":[{"vocabulary":"crossref","role":"author"},{"role":"funding-acquisition","vocabulary":"credit"},{"role":"writing-review-editing","vocabulary":"credit"},{"role":"project-administration","vocabulary":"credit"}]}],"member":"1968","published-online":{"date-parts":[[2026,10,8]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"406","DOI":"10.46690\/ager.2020.04.06","article-title":"Advances and challenges in shale oil development: A critical review","volume":"4","author":"Feng","year":"2020","journal-title":"Adv. Geo-Energy Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"951","DOI":"10.1007\/s12583-023-2000-8","article-title":"Theory, technology and practice of unconventional petroleum geology","volume":"34","author":"Zou","year":"2023","journal-title":"J. Earth Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"110183","DOI":"10.1016\/j.petrol.2022.110183","article-title":"Occurrence space and state of shale oil: A review","volume":"211","author":"Yi","year":"2022","journal-title":"J. Petro Sci. Eng."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"654","DOI":"10.1016\/j.petrol.2017.09.022","article-title":"Critical review of field EOR projects in shale and tight reservoirs","volume":"159","author":"Sheng","year":"2017","journal-title":"J. Pet. Sci. Eng."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"111185","DOI":"10.1016\/j.petrol.2022.111185","article-title":"A technical review of CO2 for enhanced oil recovery in unconventional oil reservoirs","volume":"221","author":"Chico","year":"2023","journal-title":"Geoenergy Sci. Eng."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"103173","DOI":"10.1016\/j.ijggc.2020.103173","article-title":"CO2-EOR in China: A comparative review","volume":"103","author":"Hill","year":"2020","journal-title":"Int. J. Greenh. Gas. Control"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.jiec.2023.06.018","article-title":"A comprehensive review on CO2 thickeners for CO2 mobility control in enhanced oil recovery: Recent advances and future outlook","volume":"126","author":"Emanuel","year":"2023","journal-title":"J. Ind. Eng. Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"113090","DOI":"10.1016\/j.molliq.2020.113090","article-title":"Synthesis of an oligomeric thickener for supercritical carbon dioxide and its properties","volume":"312","author":"Zhou","year":"2020","journal-title":"J. Mol. Liq."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"651","DOI":"10.1039\/D0NJ02442B","article-title":"Investigation on modified polyether as an efficient CO2 thickener","volume":"45","author":"Zhang","year":"2021","journal-title":"New J. Chem."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"122947","DOI":"10.1016\/j.fuel.2021.122947","article-title":"Carbon dioxide thickening: A review of technological aspects, advances and challenges for oilfield application","volume":"315","author":"Pal","year":"2022","journal-title":"Fuel"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"603","DOI":"10.1016\/j.petrol.2016.11.022","article-title":"An experimental study of combined foam\/surfactant polymer (SP) flooding for carbone dioxide-enhanced oil recovery (CO2-EOR)","volume":"149","author":"Xu","year":"2017","journal-title":"J. Pet. Sci. Eng."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"7127","DOI":"10.1021\/j100172a006","article-title":"Microemulsions in near-critical and supercritical carbon dioxide","volume":"95","author":"Hoefling","year":"1991","journal-title":"J. Phys. Chem."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"112846","DOI":"10.1016\/j.molliq.2020.112846","article-title":"The dissolution characteristic of nonionic surfactants in supercritical CO2","volume":"305","author":"Zhao","year":"2020","journal-title":"J. Mol. Liq."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"83","DOI":"10.1021\/la902128g","article-title":"Rod-like micelles thicken CO2","volume":"26","author":"Trickett","year":"2010","journal-title":"Langmuir"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"201","DOI":"10.1016\/j.colsurfb.2017.12.012","article-title":"Anisotropic reversed micelles with fluorocarbon-hydrocarbon hybrid surfactants in supercritical CO2","volume":"168","author":"Sagisaka","year":"2018","journal-title":"Colloid Surf. B"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2307","DOI":"10.1039\/D0EM00355G","article-title":"The High Persistence of PFAS Is Sufficient for Their Management as a Chemical Class","volume":"22","author":"Cousins","year":"2020","journal-title":"Environ. Sci. Process. Impacts"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"29461","DOI":"10.1021\/acs.jpcc.9b08589","article-title":"CO2 viscosification by functional molecules from mesoscale simulations","volume":"123","author":"Goicochea","year":"2019","journal-title":"J. Phys. Chem. C"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"e18150","DOI":"10.1002\/aic.18150","article-title":"Molecular dynamics simulation of the synergistic effect of a compound surfactant on the stability of CO2 oil-based foam","volume":"69","author":"Wang","year":"2023","journal-title":"AIChE J."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"2769","DOI":"10.1021\/acs.langmuir.5c05443","article-title":"Dynamic and Interfacially Reinforced Surfactant for Ionic Liquid Microemulsions in Supercritical CO2","volume":"42","author":"Cai","year":"2026","journal-title":"Langmuir"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"533","DOI":"10.1016\/j.petlm.2025.08.001","article-title":"Review of EOR-based techniques for enhancing sweep efficiency in carbon geo-storage","volume":"11","author":"Shehryar","year":"2025","journal-title":"Petroleum"},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Liang, S., Luo, W., Luo, Z., Wang, W., Xue, X., and Dong, B. (2023). Research of CO2-Soluble Surfactants for Enhanced Oil Recovery: Review and Outlook. Molecules, 28.","DOI":"10.3390\/molecules28248042"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"15352","DOI":"10.1021\/acs.langmuir.0c02789","article-title":"Quantum chemical study of the carbon dioxide-philicity of surfactants: Effects of tail functionalization","volume":"36","author":"Zhang","year":"2020","journal-title":"Langmuir"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"1839","DOI":"10.1021\/acs.langmuir.9b03757","article-title":"Insights into the assembly of the pseudogemini surfactant at the oil\/water interface: A molecular simulation study","volume":"36","author":"Jia","year":"2020","journal-title":"Langmuir"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1455","DOI":"10.1007\/s00214-014-1455-z","article-title":"Partial hydration of n-alkyl halides at the water-vapor interface: A molecular simulation study with atmospheric implications","volume":"133","author":"Obisesan","year":"2014","journal-title":"Theor. Chem. Acc."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"11757","DOI":"10.1039\/D5NJ01421B","article-title":"Study on the interfacial properties of binary surfactants at the oil\u2013water interface using molecular dynamics approaches","volume":"49","author":"Chen","year":"2025","journal-title":"New J. Chem."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"3151","DOI":"10.1021\/je500211w","article-title":"Diffusion Coefficients of Fluorinated Surfactants in Water: Experimental Results and Prediction by Computer Simulation","volume":"59","author":"Pereira","year":"2014","journal-title":"J. Chem. Eng. Data"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"113928","DOI":"10.1016\/j.fluid.2023.113928","article-title":"Perfluorinated Pollutants in Water: Diffusion Coefficient of Perfluorosulfonic Acids by Molecular Dynamics Simulations","volume":"575","author":"Morgado","year":"2023","journal-title":"Fluid. Phase Equilib."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"14868","DOI":"10.1073\/pnas.1906782116","article-title":"Spontaneous Self-Assembly and Structure of Perfluoroalkylalkane Surfactant Hemimicelles by Molecular Dynamics Simulations","volume":"116","author":"Silva","year":"2019","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3206","DOI":"10.1021\/acs.jpcb.5c06774","article-title":"Molecular-Scale Insights into the Interactions between Per-fluoroalkyl Substances and Polyethylene","volume":"130","author":"Thomaz","year":"2026","journal-title":"J. Phys. Chem. B"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"8775","DOI":"10.1021\/jp203241q","article-title":"Optimized Unlike-Pair Interactions for Water-Carbon Dioxide Mix-tures Described by the SPC\/E and EPM2 Models","volume":"115","author":"Vlcek","year":"2011","journal-title":"J. Phys. Chem. B"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2157","DOI":"10.1002\/jcc.21224","article-title":"PACKMOL: A package for building initial configurations for molecular dynamics simulations","volume":"30","author":"Andrade","year":"2009","journal-title":"J. Comput. Chem."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"1059","DOI":"10.1021\/je000236i","article-title":"The NIST Chemistry WebBook: A chemical data resource on the internet","volume":"46","author":"Linstrom","year":"2001","journal-title":"J. Chem. Eng. Data"},{"key":"ref_33","unstructured":"Frisch, M.E., Trucks, G.W., and Schlegel, H.B. (2016). Gaussian 16, Gaussian, Inc."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1103\/PhysRevB.37.785","article-title":"Development of the Colle-Salvetti correlation-energy formula into a functional of the electron density","volume":"37","author":"Lee","year":"1988","journal-title":"Phys. Rev. B"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"3297","DOI":"10.1039\/b508541a","article-title":"Balanced basis sets of split valence, triple zeta valence and quadruple zeta valence quality for H to Rn: Design and assessment of accuracy","volume":"7","author":"Weigend","year":"2005","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1701","DOI":"10.1002\/jcc.20291","article-title":"GROMACS: Fast, flexible, and free","volume":"26","author":"Lindahl","year":"2005","journal-title":"J. Comput. Chem."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"435","DOI":"10.1021\/ct700301q","article-title":"GROMACS 4: Algorithms for highly efficient, load-balanced, and scalable molecular simulation","volume":"4","author":"Hess","year":"2008","journal-title":"J. Chem. Theory Comput."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"014101","DOI":"10.1063\/1.2408420","article-title":"Canonical sampling through velocity rescaling","volume":"126","author":"Bussi","year":"2007","journal-title":"J. Chem. Phys."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1021\/ct700200b","article-title":"P-LINCS: A parallel linear constraint solver for molecular simulation","volume":"4","author":"Hess","year":"2008","journal-title":"J. Chem. Theory Comput."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"8577","DOI":"10.1063\/1.470117","article-title":"A smooth particle mesh Ewald method","volume":"103","author":"Essmann","year":"1995","journal-title":"J. Chem. Phys."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"33","DOI":"10.1016\/0263-7855(96)00018-5","article-title":"VMD: Visual molecular dynamics","volume":"14","author":"Humphrey","year":"1996","journal-title":"J. Mol. Graph. Model."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/19\/3576\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,10,8]],"date-time":"2026-10-08T15:17:23Z","timestamp":1791472643000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/31\/19\/3576"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,10,8]]},"references-count":41,"journal-issue":{"issue":"19","published-online":{"date-parts":[[2026,10]]}},"alternative-id":["molecules31193576"],"URL":"https:\/\/doi.org\/10.3390\/molecules31193576","relation":{},"ISSN":["1420-3049"],"issn-type":[{"value":"1420-3049","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,10,8]]}}}