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Molecular Dynamics Study of a Surfactant-Mediated Decane−Water Interface: Effect of Molecular Architecture of Alkyl Benzene Sulfonate

Jang, Seung Soon and Lin, Shiang-Tai and Maiti, Prabal K. and Blanco, Mario and Goddard, William A., III and Shuler, Patrick and Tang, Yongchun (2004) Molecular Dynamics Study of a Surfactant-Mediated Decane−Water Interface: Effect of Molecular Architecture of Alkyl Benzene Sulfonate. Journal of Physical Chemistry B, 108 (32). pp. 12130-12140. ISSN 1520-6106. doi:10.1021/jp048773n.

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The effect of molecular architecture of a surfactant, particularly the attachment position of benzene sulfonate on the hexadecane backbone, at the decane−water interface was investigated using atomistic MD simulations. We consider a series of surfactant isomers in the family of alkyl benzene sulfonates, denoted by m-C16, indicating a benzene sulfonate group attached to the mth carbon in a hexadecane backbone. The equilibrated model systems showed a well-defined interface between the decane and water phases. We find that surfactant 4-C16 has a more compact packing, in terms of the interfacial area and molecular alignment at the interface, than other surfactants simulated in this study. Furthermore, surfactant 4-C16 leads to the most stable interface by having the lowest interface formation energy. The interfacial thickness is the largest in the case of surfactant 4-C16, with the thickness decreasing when the benzene sulfonate is located farther from the attachment position of 4-C16 (the 4th carbon). The interfacial tension profile was calculated along the direction perpendicular to the interface using the Kirkwood−Buff theory. From the comparison of the interfacial tension obtained from the interfacial tension profile, we found that surfactant 4-C16 induces the lowest interfacial tension and that the interfacial tension increases with decreasing interfacial thickness as a function of the attachment position of benzene sulfonate. Such a relationship between the interfacial thickness and interfacial tension is rationalized in terms of the miscibility of the alkyl tail of surfactant m-C16 with decane by comparing the “effective” length of the alkyl tail with the average end-to-end length of decane. Among the surfactants, the effective length of the 4-C16 alkyl tail (9.53 ± 1.36 Å) was found to be closest to that of decane (9.97 ± 1.03 Å), which is consistent with the results from the density profile and the interfacial tension profile.

Item Type:Article
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URLURL TypeDescription
Jang, Seung Soon0000-0002-1920-421X
Lin, Shiang-Tai0000-0001-8513-8196
Maiti, Prabal K.0000-0002-9956-1136
Goddard, William A., III0000-0003-0097-5716
Additional Information:© 2004 American Chemical Society. Received: March 18, 2004; In Final Form: May 25, 2004. Publication Date (Web): July 10, 2004. This research was supported in part by the Department of Energy (DE-FC26-01BC15362, Paul West). The facilities of the Materials and Process Simulation Center used for these studies are supported by DURIP-ARO, DURIP-ONR, IBM-SUR, and NSF (MRI), and other support for the MSC comes from MURI-ARO, MURI-ONR, DOE, ONR, NSF-CSEM, NIH, General Motors, ChevronTexaco, Seiko-Epson, Beckman Institute, and Asahi Kasei.
Funding AgencyGrant Number
Department of Energy (DOE)DE-FC26-01BC15362
Army Research Office (ARO)UNSPECIFIED
Office of Naval Research (ONR)UNSPECIFIED
Caltech Beckman InstituteUNSPECIFIED
Issue or Number:32
Record Number:CaltechAUTHORS:20170315-155508293
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Official Citation:Molecular Dynamics Study of a Surfactant-Mediated Decane−Water Interface:  Effect of Molecular Architecture of Alkyl Benzene Sulfonate Seung Soon Jang, Shiang-Tai Lin,Prabal K. Maiti, Mario Blanco, William A. Goddard III, Patrick Shuler, and Yongchun Tang The Journal of Physical Chemistry B 2004 108 (32), 12130-12140 DOI: 10.1021/jp048773n
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:75162
Deposited By: Tony Diaz
Deposited On:16 Mar 2017 16:40
Last Modified:15 Nov 2021 16:31

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