{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,13]],"date-time":"2026-10-13T20:45:16Z","timestamp":1791924316147,"version":"4.3.4"},"reference-count":41,"publisher":"American Chemical Society (ACS)","issue":"40","license":[{"start":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T00:00:00Z","timestamp":1790726400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Applied Technology Research and Development Program Project in Heilongjiang Province","award":["GA20A201"],"award-info":[{"award-number":["GA20A201"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,10,13]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Reducing the oil-to-water ratio (OWR) in oil-based drilling fluids (OBDFs) offers significant economic and environmental benefits, yet severely challenges emulsion stability at high temperatures. To address this issue, we designed a thermoresponsive amphiphilic copolymer that dynamically reinforces the oil\u2013water interface upon heating, thereby stabilizing low-OWR emulsions at elevated temperatures. Here, we report a thermoresponsive amphiphilic copolymer, poly(St-NIPAM-AMPS) (PSNA), synthesized via free-radical polymerization, as a primary emulsifier for low-OWR OBDFs. PSNA incorporates styrene (St) as a hydrophobic anchor, N-isopropylacrylamide (NIPAM) as a thermoresponsive unit, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) as an electrostatic stabilizer. Systematic optimization identified PSNA-2 (St:NIPAM:AMPS = 1:1:1) as the optimal composition. At an emulsifier loading of 6 wt % and an OWR of 70:30, the PSNA-2-based OBDF achieved an electrical stability of 879 V, a high-temperature, high-pressure filtration loss of 3.2 mL, and a sag factor of 0.513 after dynamic aging at 180 \u00b0C for 16 h, meeting all industry criteria. Mechanistic studies reveal a thermally triggered interfacial self-reinforcement mechanism: above its lower critical solution temperature (54 \u00b0C), the NIPAM segments collapse, densifying the interfacial film, while the AMPS groups provide sustained electrostatic repulsion. The PSNA-2 formulation also exhibits a nontoxic environmental profile (EC50 &amp;gt; 30,000 mg\/L). This work offers a scalable, cost-effective emulsifier design for high-performance, low-OWR OBDFs.<\/jats:p>","DOI":"10.1021\/acsomega.6c08519","type":"journal-article","created":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T06:02:01Z","timestamp":1790748121000},"page":"62139-62151","source":"Crossref","is-referenced-by-count":0,"title":["Thermoresponsive\nAmphiphilic Polymer Emulsifier for\nLow-Dosage, High-Stability Oil-Based Drilling Fluids"],"prefix":"10.1021","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0009-0002-8683-5721","authenticated-orcid":true,"given":"Dapeng","family":"Zou","sequence":"first","affiliation":[{"name":"Northeast Petroleum University , , ,","place":["Daqing, China, 163318"]},{"name":"Drilling Fluid Company, Daqing Drilling & Exploration Engineering Corporation , ,","place":["Daqing, China, 163413"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jun","family":"Wang","sequence":"additional","affiliation":[{"name":"Northeast Petroleum University , , ,","place":["Daqing, China, 163318"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"316","published-online":{"date-parts":[[2026,9,30]]},"reference":[{"issue":"1","key":"2026101315071551400_cit1","doi-asserted-by":"publisher","DOI":"10.3390\/gels12010074","article-title":"Oil-Water Biphasic\nMetal-Organic Supramolecular Gel for Lost Circulation Control: Formulation\nOptimization, Gelation Mechanism, and Plugging Performance","volume":"12","author":"Li","year":"2026","journal-title":"GELS"},{"issue":"11","key":"2026101315071551400_cit2","doi-asserted-by":"publisher","first-page":"5696","DOI":"10.1021\/acs.iecr.5c05068","article-title":"Mechanistic Insights into Dual-Organoclay\nInteractions for Enhanced HPHT Oil-Based Drilling Fluids","volume":"65","author":"Mahmoud","year":"2026","journal-title":"Ind. Eng. Chem. Res."},{"issue":"2","key":"2026101315071551400_cit3","doi-asserted-by":"publisher","DOI":"10.3390\/pr14020208","article-title":"Developing New Water-Based\nDrilling Fluid Additives\nfor Mitigating Filtration Loss at High Pressure and High Temperature","volume":"14","author":"Sulakshana","year":"2026","journal-title":"Processes"},{"key":"2026101315071551400_cit4","doi-asserted-by":"publisher","DOI":"10.1016\/j.colsurfa.2026.140369","article-title":"Hydrophobically\nmodified tea saponin from Camellia oleifera seed meal: A sustainable\nsurfactant with enhanced foaming, emulsifying, and high-temperature\nstability for harsh conditions in oilfield applications","volume":"742","author":"Xiao","year":"2026","journal-title":"Colloids Surf., A"},{"key":"2026101315071551400_cit5","doi-asserted-by":"publisher","first-page":"180","DOI":"10.1016\/j.aej.2026.03.004","article-title":"Tailoring smart\nand high-performance drilling fluids with supramolecular\nmaterials: Advances in water-and oil-based systems","volume":"141","author":"Yang","year":"2026","journal-title":"Alexandria Eng. 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Macromol."},{"key":"2026101315071551400_cit8","doi-asserted-by":"publisher","DOI":"10.1016\/j.matchemphys.2026.132186","article-title":"Structure-function\nanalysis of an\nIllite-montmorillonite organoclay blend for HPHT oil-based drilling\nfluids","volume":"354","author":"Mahmoud","year":"2026","journal-title":"Mater. Chem. Phys."},{"issue":"4","key":"2026101315071551400_cit9","doi-asserted-by":"publisher","first-page":"1069","DOI":"10.1007\/s10553-024-01768-w","article-title":"Development\nand Application of a\nOligomeric Emulsifier with High-Temperature Resistant","volume":"60","author":"Xudong","year":"2024","journal-title":"Chem. Technol. 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Technol."},{"issue":"21","key":"2026101315071551400_cit13","doi-asserted-by":"publisher","DOI":"10.3390\/molecules28217407","article-title":"The Phase Inversion\nMechanism of the pH-Sensitive Reversible Invert Emulsion","volume":"28","author":"Liu","year":"2023","journal-title":"Molecules"},{"issue":"1","key":"2026101315071551400_cit14","doi-asserted-by":"publisher","DOI":"10.3390\/molecules29010062","article-title":"Study on the Properties\nChanges of Reversible Invert Emulsion during the Process from O\/W\nto W\/O with Alkali","volume":"29","author":"Liu","year":"2024","journal-title":"Molecules"},{"issue":"6","key":"2026101315071551400_cit15","doi-asserted-by":"publisher","DOI":"10.3390\/molecules29061269","article-title":"Preparation and\nProperties of Reversible Emulsion Drilling Fluid Stabilized by Modified\nNanocrystalline Cellulose","volume":"29","author":"Liu","year":"2024","journal-title":"Molecules"},{"key":"2026101315071551400_cit16","doi-asserted-by":"publisher","DOI":"10.1016\/j.petrol.2022.111053","article-title":"Enhanced\nstability of low oil-to-water ratio water-in-oil emulsions (oil-based\ndrilling fluids): Synergistic effect of nano-SiO2 and emulsifiers","volume":"219","author":"Pu","year":"2022","journal-title":"J. Pet. Sci. Eng."},{"key":"2026101315071551400_cit17","doi-asserted-by":"publisher","DOI":"10.1016\/j.colsurfa.2019.124246","article-title":"Smart Pickering water-in-oil emulsion by manipulating\ninteractions between nanoparticles and surfactant as potential oil-based\ndrilling fluid","volume":"586","author":"Liu","year":"2020","journal-title":"Colloids Surf., A"},{"key":"2026101315071551400_cit18","doi-asserted-by":"publisher","DOI":"10.1016\/j.colsurfa.2025.139268","article-title":"pH-responsive\nphase invert emulsion stabilized by branched amide surfactant for\nreversible invert emulsion drilling fluid","volume":"733","author":"Li","year":"2026","journal-title":"Colloids\nSurf., A"},{"issue":"1","key":"2026101315071551400_cit19","doi-asserted-by":"publisher","DOI":"10.32604\/jpm.2026.077100","article-title":"Synergistic Emulsifier System Based on Molecular Design\nfor Ultra-Low Oil-to-Water Ratio Oil-Based Drilling Fluids","volume":"43","author":"Wang","year":"2026","journal-title":"J. Polym. 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Commun."},{"issue":"4","key":"2026101315071551400_cit26","doi-asserted-by":"publisher","DOI":"10.1002\/mabi.202200554","article-title":"Injectable\nPolyzwitterionic Lubricant for Complete Prevention of Cardiac Adhesion","volume":"23","author":"Wang","year":"2023","journal-title":"Macromol. Biosci."},{"issue":"1","key":"2026101315071551400_cit27","doi-asserted-by":"publisher","DOI":"10.1038\/s41467-023-43291-2","article-title":"Anhydrous interfacial\npolymerization of sub-1 \u00c5 sieving polyamide membrane","volume":"14","author":"Zhao","year":"2023","journal-title":"Nat. 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Interfaces"},{"issue":"4","key":"2026101315071551400_cit29","doi-asserted-by":"publisher","DOI":"10.3390\/buildings14041063","article-title":"Incorporation of Disposed\nFace Mask to Cement Mortar Material: An Insight into the Dynamic Mechanical\nProperties","volume":"14","author":"Nie","year":"2024","journal-title":"Buildings"},{"key":"2026101315071551400_cit30","doi-asserted-by":"publisher","first-page":"61","DOI":"10.1016\/j.petrol.2017.11.067","article-title":"Effect of\nnanoparticles on the modifications of drilling fluids properties:\nA review of recent advances","volume":"161","author":"Rafati","year":"2018","journal-title":"J. Pet. Sci. Eng."},{"key":"2026101315071551400_cit31","doi-asserted-by":"publisher","first-page":"369","DOI":"10.1016\/j.petrol.2016.05.045","article-title":"Improving\ndrilling performance with continuous online measurements of electrical\nstability and conductivity in oil based drilling fluids","volume":"146","author":"Magalha\u0303es","year":"2016","journal-title":"J. Pet. Sci. Eng."},{"issue":"40","key":"2026101315071551400_cit32","doi-asserted-by":"publisher","first-page":"41250","DOI":"10.1021\/acsomega.4c03083","article-title":"Investigating on the Performance\nand Mechanism of Poly(styrene-methyl\nmethacrylate-ethyl methacrylate-butyl acrylate) as Nano Sealing Agent\nin Oil-Based Drilling Fluids","volume":"9","author":"Yang","year":"2024","journal-title":"ACS Omega"},{"key":"2026101315071551400_cit33","article-title":"Rheological\nAnalysis of Static and Dynamic Sag in Drilling Fluids","author":"Maxey","year":"2007","journal-title":"Annu. Trans. \u2013 Nord. Rheol. Soc."},{"issue":"5","key":"2026101315071551400_cit34","doi-asserted-by":"publisher","first-page":"1215","DOI":"10.1016\/S1876-3804(23)60460-4","article-title":"A high-temperature resistant and high-density polymeric\nsaturated brine-based drilling fluid","volume":"50","author":"Huang","year":"2023","journal-title":"Pet. Explor.\nDev."},{"issue":"6","key":"2026101315071551400_cit35","doi-asserted-by":"publisher","first-page":"2959","DOI":"10.1016\/j.petsci.2022.07.003","article-title":"A new environmentally\nfriendly water-based drilling fluids with laponite nanoparticles and\npolysaccharide\/polypeptide derivatives","volume":"19","author":"Li","year":"2022","journal-title":"Pet.\nSci."},{"issue":"1181","key":"2026101315071551400_cit36","doi-asserted-by":"publisher","first-page":"567","DOI":"10.1098\/rstb.1987.0039","article-title":"Effects of Discarded Drill Muds on\nMicrobial-populations","volume":"316","author":"Sanders","year":"1987","journal-title":"Philos. Trans. R. Soc.,\nB"},{"key":"2026101315071551400_cit37","doi-asserted-by":"publisher","DOI":"10.1016\/j.colsurfa.2019.124246","article-title":"Smart Pickering Water-in-Oil\nEmulsion by Manipulating Interactions between Nanoparticles and Surfactant\nas Potential Oil-Based Drilling Fluid","volume":"586","author":"Liu","year":"2019","journal-title":"Colloids\nSurf., A"},{"key":"2026101315071551400_cit38","doi-asserted-by":"publisher","first-page":"202","DOI":"10.1016\/j.clay.2010.11.017","article-title":"In-situ FTIR analyses\nof bentonite\nunder high-pressure","volume":"51","author":"Alabarse","year":"2011","journal-title":"Appl. Clay Sci."},{"key":"2026101315071551400_cit39","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/j.scitotenv.2013.08.028","article-title":"Bioassay based\nluminescent bacteria: Interferences, improvements,\nand applications","volume":"468\u2013469","author":"Ma","year":"2014","journal-title":"Sci. Total Environ."},{"key":"2026101315071551400_cit40","doi-asserted-by":"publisher","first-page":"408","DOI":"10.1016\/j.petrol.2017.06.022","article-title":"Environmental-friendly\nsalt water mud with nano-SiO2 in horizontal drilling for shale gas","volume":"156","author":"Yang","year":"2017","journal-title":"J. Pet. Sci. 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