Wormlike emulsion droplets

Forming an interface between immiscible fluids incurs a free-energy cost that usually favors minimizing the interfacial area. An emulsion droplet of fixed volume therefore tends to form a sphere, and pairs of droplets tend to coalesce. Surfactant molecules adsorbed to the droplets' surfaces sta...

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Main Authors: Jatin Abacousnac, Wenjun Chen, Jasna Brujic, David G. Grier
Format: Article
Language:English
Published: American Physical Society 2025-07-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/3g85-ncsj
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author Jatin Abacousnac
Wenjun Chen
Jasna Brujic
David G. Grier
author_facet Jatin Abacousnac
Wenjun Chen
Jasna Brujic
David G. Grier
author_sort Jatin Abacousnac
collection DOAJ
description Forming an interface between immiscible fluids incurs a free-energy cost that usually favors minimizing the interfacial area. An emulsion droplet of fixed volume therefore tends to form a sphere, and pairs of droplets tend to coalesce. Surfactant molecules adsorbed to the droplets' surfaces stabilize emulsions by providing a kinetic barrier to coalescence. Here, we show that the pressure exerted by bound surfactant molecules also competes with the droplet's intrinsic surface tension and can reverse the sign of the overall surface free energy. The onset of negative surface tension favors maximizing surface area and therefore favors elongation into a wormlike morphology. Analyzing this system in the Gibbs grand canonical ensemble reveals a phase transition between spherical and wormlike emulsions that is governed by the chemical potential of surfactant molecules in solution. Predictions based on this model agree with the observed behavior of an experimental model system composed of lipid-stabilized silicone oil droplets in an aqueous surfactant solution.
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spelling doaj-art-320a53fa2ee144979f96699bb523fe932025-08-20T02:42:00ZengAmerican Physical SocietyPhysical Review Research2643-15642025-07-017303301010.1103/3g85-ncsjWormlike emulsion dropletsJatin AbacousnacWenjun ChenJasna BrujicDavid G. GrierForming an interface between immiscible fluids incurs a free-energy cost that usually favors minimizing the interfacial area. An emulsion droplet of fixed volume therefore tends to form a sphere, and pairs of droplets tend to coalesce. Surfactant molecules adsorbed to the droplets' surfaces stabilize emulsions by providing a kinetic barrier to coalescence. Here, we show that the pressure exerted by bound surfactant molecules also competes with the droplet's intrinsic surface tension and can reverse the sign of the overall surface free energy. The onset of negative surface tension favors maximizing surface area and therefore favors elongation into a wormlike morphology. Analyzing this system in the Gibbs grand canonical ensemble reveals a phase transition between spherical and wormlike emulsions that is governed by the chemical potential of surfactant molecules in solution. Predictions based on this model agree with the observed behavior of an experimental model system composed of lipid-stabilized silicone oil droplets in an aqueous surfactant solution.http://doi.org/10.1103/3g85-ncsj
spellingShingle Jatin Abacousnac
Wenjun Chen
Jasna Brujic
David G. Grier
Wormlike emulsion droplets
Physical Review Research
title Wormlike emulsion droplets
title_full Wormlike emulsion droplets
title_fullStr Wormlike emulsion droplets
title_full_unstemmed Wormlike emulsion droplets
title_short Wormlike emulsion droplets
title_sort wormlike emulsion droplets
url http://doi.org/10.1103/3g85-ncsj
work_keys_str_mv AT jatinabacousnac wormlikeemulsiondroplets
AT wenjunchen wormlikeemulsiondroplets
AT jasnabrujic wormlikeemulsiondroplets
AT davidggrier wormlikeemulsiondroplets