{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T19:00:40Z","timestamp":1785438040741,"version":"3.56.0"},"reference-count":27,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T00:00:00Z","timestamp":1784160000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"the Major Scientific and Technological Innovation Projects in Shandong Province","award":["2025ZLGX07"],"award-info":[{"award-number":["2025ZLGX07"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"crossref","award":["52304061"],"award-info":[{"award-number":["52304061"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"award":["52304061"],"award-info":[{"award-number":["52304061"]}],"id":[{"id":"https:\/\/ror.org\/01h0zpd94","id-type":"ROR","asserted-by":"publisher"}]},{"name":"the Postdoctoral Fellowship Program of CPSF","award":["GZB20240851"],"award-info":[{"award-number":["GZB20240851"]}]},{"name":"the Natural Science Foundation of Shandong Province of China","award":["ZR2024QE088"],"award-info":[{"award-number":["ZR2024QE088"]}]},{"name":"the Qingdao Postdoctoral Funding Project","award":["QDBSH20240201005"],"award-info":[{"award-number":["QDBSH20240201005"]}]},{"name":"the Fundamental Research Funds for the Central Universities","award":["24CX06040A"],"award-info":[{"award-number":["24CX06040A"]}]},{"name":"the Project of Gansu Provincial Joint Research Fund","award":["24JRRM011"],"award-info":[{"award-number":["24JRRM011"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Wormlike micelles provide the structural basis for the viscoelasticity of clean fracturing fluids, yet the molecular mechanism by which calcium-containing brine regulates their growth remains insufficiently understood. In this work, all-atom molecular dynamics simulations were performed to investigate the calcium-regulated self-assembly of an EAHSB\/EHAC\/NaPts surfactant\u2013counterion system. In the absence of Ca2+, dispersed surfactant and counterion molecules first formed small spherical aggregates, which subsequently fused into larger micelles, rod-like intermediates, and finally wormlike micelles. Increasing the local surfactant\/counterion loading further promoted one-dimensional micellar growth and network-like association. When Ca2+ was introduced, the assembly process became slower and the final aggregate morphology shifted from elongated wormlike micelles to smaller spherical aggregates. Radial distribution functions and coordination-number analysis show that Ca2+ redistributes charged-group correlations within the mixed surfactant\/counterion assemblies. Hydration analysis indicates enlarged polar hydration shells, whereas hydrophobic-tail hydration and gauche-defect probabilities reveal enhanced tail exposure and looser chain packing. These results demonstrate that Ca2+ suppresses wormlike micelle growth through coupled electrostatic redistribution, interfacial hydration, and hydrophobic-chain disorder, thereby favoring high-curvature spherical aggregates over extended wormlike networks.<\/jats:p>","DOI":"10.3390\/molecules31142490","type":"journal-article","created":{"date-parts":[[2026,7,17]],"date-time":"2026-07-17T00:55:59Z","timestamp":1784249759000},"page":"2490","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Calcium-Regulated Self-Assembly of Zwitterionic\/Cationic Surfactant\u2013Counterion Complexes: Molecular Dynamics Insights into the Suppression of Wormlike Micelle Growth"],"prefix":"10.3390","volume":"31","author":[{"given":"Yazhou","family":"Wang","sequence":"first","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fajun","family":"Guo","sequence":"additional","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiaonan","family":"Feng","sequence":"additional","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hongmei","family":"Wang","sequence":"additional","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhao","family":"Xue","sequence":"additional","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shuai","family":"Zhang","sequence":"additional","affiliation":[{"name":"PetroChina Huabei Oilfield Company, Renqiu 062552, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0497-4948","authenticated-orcid":false,"given":"Mingwei","family":"Gao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Deep Oil and Gas, China University of Petroleum (East China), Qingdao 266580, China"},{"name":"Key Laboratory of Unconventional Oil & Gas Development, School of Petroleum Engineering, China University of Petroleum (East China), Ministry of Education, Qingdao 266580, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,7,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"7174","DOI":"10.1039\/c3cs35490c","article-title":"Smart Wormlike Micelles","volume":"42","author":"Chu","year":"2013","journal-title":"Chem. 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