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Title: Temperature-Tuned Faceting and Shape Changes in Liquid Alkane Droplets

Recent extensive studies reveal that surfactant-stabilized spherical alkane emulsion droplets spontaneously adopt polyhedral shapes upon cooling below a temperature T d while remaining liquid. Further cooling induces the growth of tails and spontaneous droplet splitting. Two mechanisms were offered to account for these intriguing effects. One assigns the effects to the formation of an intradroplet frame of tubules consisting of crystalline rotator phases with cylindrically curved lattice planes. The second assigns the sphere-to-polyhedron transition to the buckling of defects in a crystalline interfacial monolayer, known to form in these systems at some T s > T d. The buckling reduces the extensional energy of the crystalline monolayer’s defects, unavoidably formed when wrapping a spherical droplet by a hexagonally packed interfacial monolayer. The tail growth, shape changes, and droplet splitting were assigned to the decrease and vanishing of surface tension, γ. Here we present temperature-dependent γ(T), optical microscopy measurements, and interfacial entropy determinations for several alkane/surfactant combinations. We demonstrate the advantages and accuracy of the in situ γ(T) measurements made simultaneously with the microscopy measurements on the same droplet. The in situ and coinciding ex situ Wilhelmy plate γ(T) measurements confirm the low interfacial tension, ≲0.1 mN/m, observed at T d.more » Here, our results provide strong quantitative support validating the crystalline monolayer buckling mechanism.« less
Authors:
 [1] ;  [1] ;  [2] ;  [1] ; ORCiD logo [1]
  1. Bar-llan Univ., Ramat-Gan (Israel)
  2. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-114003-2017-JA
Journal ID: ISSN 0743-7463
Grant/Contract Number:
SC00112704
Type:
Accepted Manuscript
Journal Name:
Langmuir
Additional Journal Information:
Journal Volume: 33; Journal Issue: 5; Journal ID: ISSN 0743-7463
Publisher:
American Chemical Society
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
77 NANOSCIENCE AND NANOTECHNOLOGY
OSTI Identifier:
1376116

Guttman, Shani, Sapir, Zvi, Ocko, Benjamin M., Deutsch, Moshe, and Sloutskin, Eli. Temperature-Tuned Faceting and Shape Changes in Liquid Alkane Droplets. United States: N. p., Web. doi:10.1021/acs.langmuir.6b02926.
Guttman, Shani, Sapir, Zvi, Ocko, Benjamin M., Deutsch, Moshe, & Sloutskin, Eli. Temperature-Tuned Faceting and Shape Changes in Liquid Alkane Droplets. United States. doi:10.1021/acs.langmuir.6b02926.
Guttman, Shani, Sapir, Zvi, Ocko, Benjamin M., Deutsch, Moshe, and Sloutskin, Eli. 2017. "Temperature-Tuned Faceting and Shape Changes in Liquid Alkane Droplets". United States. doi:10.1021/acs.langmuir.6b02926. https://www.osti.gov/servlets/purl/1376116.
@article{osti_1376116,
title = {Temperature-Tuned Faceting and Shape Changes in Liquid Alkane Droplets},
author = {Guttman, Shani and Sapir, Zvi and Ocko, Benjamin M. and Deutsch, Moshe and Sloutskin, Eli},
abstractNote = {Recent extensive studies reveal that surfactant-stabilized spherical alkane emulsion droplets spontaneously adopt polyhedral shapes upon cooling below a temperature Td while remaining liquid. Further cooling induces the growth of tails and spontaneous droplet splitting. Two mechanisms were offered to account for these intriguing effects. One assigns the effects to the formation of an intradroplet frame of tubules consisting of crystalline rotator phases with cylindrically curved lattice planes. The second assigns the sphere-to-polyhedron transition to the buckling of defects in a crystalline interfacial monolayer, known to form in these systems at some Ts > Td. The buckling reduces the extensional energy of the crystalline monolayer’s defects, unavoidably formed when wrapping a spherical droplet by a hexagonally packed interfacial monolayer. The tail growth, shape changes, and droplet splitting were assigned to the decrease and vanishing of surface tension, γ. Here we present temperature-dependent γ(T), optical microscopy measurements, and interfacial entropy determinations for several alkane/surfactant combinations. We demonstrate the advantages and accuracy of the in situ γ(T) measurements made simultaneously with the microscopy measurements on the same droplet. The in situ and coinciding ex situ Wilhelmy plate γ(T) measurements confirm the low interfacial tension, ≲0.1 mN/m, observed at Td. Here, our results provide strong quantitative support validating the crystalline monolayer buckling mechanism.},
doi = {10.1021/acs.langmuir.6b02926},
journal = {Langmuir},
number = 5,
volume = 33,
place = {United States},
year = {2017},
month = {1}
}