Synthesis and Stability of Water-in-Oil Emulsion Using Partially Reduced Graphene Oxide as a Tailored Surfactant

Tanesh D. Gamot, Arup Ranjan Bhattacharyya, Tam Sridhar, Fiona Beach, Rico F. Tabor, Mainak Majumder

Research output: Contribution to journalArticleResearchpeer-review

Abstract

Graphene oxide (GO) is widely known as an amphiphile having hydrophilic oxygen functionality and unoxidized graphitic patches as the hydrophobic domains. Exploiting this amphiphilicity, GO serves as a surfactant to stabilize oil-water interfaces. While there are numerous reports on GO as a surfactant, most of these reports concern oil-in-water (O/W) emulsions, and there are very few on the formation of water-in-oil (W/O) emulsions. We prepared W/O emulsions using partially reduced graphene oxide (prGO) as a surfactant. The partial reduction introduces a subtle hydrophilic-lipophilic balance (HLB), which favors the formation of the W/O emulsion. The morphological features and rheological characteristics of the W/O emulsion with 75:25 water-to-oil ratio were investigated and analyzed in detail. The W/O emulsion was found to have polydispersity with wide range of droplet sizes varying between 2 to 500 μm. Using confocal microscopy, the role of parameters such as extent of reduction, continuous phase volume fraction and the concentration of GO on the stability, microstructure and variation of droplet size distribution of the W/O emulsion were carefully monitored. With prGO concentration as large as 0.05% (w/w), highly concentrated emulsion will form, and are stable up to 20 days from formation; destabilization occurred from sedimentation and subsequent coalescence as the partially reduced GO was limited by its dispersion ability in the oil-phase studied here. Understanding the mechanisms behind the transient stability will enable the development of novel emulsion compositions containing GO as a multifunctional additive.

Original languageEnglish
Pages (from-to)10311-10321
Number of pages11
JournalLangmuir
Volume33
Issue number39
DOIs
Publication statusPublished - 3 Oct 2017

Cite this

@article{19a9383a88c048b3908d12db6d68a2c2,
title = "Synthesis and Stability of Water-in-Oil Emulsion Using Partially Reduced Graphene Oxide as a Tailored Surfactant",
abstract = "Graphene oxide (GO) is widely known as an amphiphile having hydrophilic oxygen functionality and unoxidized graphitic patches as the hydrophobic domains. Exploiting this amphiphilicity, GO serves as a surfactant to stabilize oil-water interfaces. While there are numerous reports on GO as a surfactant, most of these reports concern oil-in-water (O/W) emulsions, and there are very few on the formation of water-in-oil (W/O) emulsions. We prepared W/O emulsions using partially reduced graphene oxide (prGO) as a surfactant. The partial reduction introduces a subtle hydrophilic-lipophilic balance (HLB), which favors the formation of the W/O emulsion. The morphological features and rheological characteristics of the W/O emulsion with 75:25 water-to-oil ratio were investigated and analyzed in detail. The W/O emulsion was found to have polydispersity with wide range of droplet sizes varying between 2 to 500 μm. Using confocal microscopy, the role of parameters such as extent of reduction, continuous phase volume fraction and the concentration of GO on the stability, microstructure and variation of droplet size distribution of the W/O emulsion were carefully monitored. With prGO concentration as large as 0.05{\%} (w/w), highly concentrated emulsion will form, and are stable up to 20 days from formation; destabilization occurred from sedimentation and subsequent coalescence as the partially reduced GO was limited by its dispersion ability in the oil-phase studied here. Understanding the mechanisms behind the transient stability will enable the development of novel emulsion compositions containing GO as a multifunctional additive.",
author = "Gamot, {Tanesh D.} and Bhattacharyya, {Arup Ranjan} and Tam Sridhar and Fiona Beach and Tabor, {Rico F.} and Mainak Majumder",
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day = "3",
doi = "10.1021/acs.langmuir.7b02320",
language = "English",
volume = "33",
pages = "10311--10321",
journal = "Langmuir: the ACS journal of surfaces and colloids",
issn = "0743-7463",
publisher = "American Chemical Society (ACS)",
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Synthesis and Stability of Water-in-Oil Emulsion Using Partially Reduced Graphene Oxide as a Tailored Surfactant. / Gamot, Tanesh D.; Bhattacharyya, Arup Ranjan; Sridhar, Tam; Beach, Fiona; Tabor, Rico F.; Majumder, Mainak.

In: Langmuir, Vol. 33, No. 39, 03.10.2017, p. 10311-10321.

Research output: Contribution to journalArticleResearchpeer-review

TY - JOUR

T1 - Synthesis and Stability of Water-in-Oil Emulsion Using Partially Reduced Graphene Oxide as a Tailored Surfactant

AU - Gamot, Tanesh D.

AU - Bhattacharyya, Arup Ranjan

AU - Sridhar, Tam

AU - Beach, Fiona

AU - Tabor, Rico F.

AU - Majumder, Mainak

PY - 2017/10/3

Y1 - 2017/10/3

N2 - Graphene oxide (GO) is widely known as an amphiphile having hydrophilic oxygen functionality and unoxidized graphitic patches as the hydrophobic domains. Exploiting this amphiphilicity, GO serves as a surfactant to stabilize oil-water interfaces. While there are numerous reports on GO as a surfactant, most of these reports concern oil-in-water (O/W) emulsions, and there are very few on the formation of water-in-oil (W/O) emulsions. We prepared W/O emulsions using partially reduced graphene oxide (prGO) as a surfactant. The partial reduction introduces a subtle hydrophilic-lipophilic balance (HLB), which favors the formation of the W/O emulsion. The morphological features and rheological characteristics of the W/O emulsion with 75:25 water-to-oil ratio were investigated and analyzed in detail. The W/O emulsion was found to have polydispersity with wide range of droplet sizes varying between 2 to 500 μm. Using confocal microscopy, the role of parameters such as extent of reduction, continuous phase volume fraction and the concentration of GO on the stability, microstructure and variation of droplet size distribution of the W/O emulsion were carefully monitored. With prGO concentration as large as 0.05% (w/w), highly concentrated emulsion will form, and are stable up to 20 days from formation; destabilization occurred from sedimentation and subsequent coalescence as the partially reduced GO was limited by its dispersion ability in the oil-phase studied here. Understanding the mechanisms behind the transient stability will enable the development of novel emulsion compositions containing GO as a multifunctional additive.

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U2 - 10.1021/acs.langmuir.7b02320

DO - 10.1021/acs.langmuir.7b02320

M3 - Article

VL - 33

SP - 10311

EP - 10321

JO - Langmuir: the ACS journal of surfaces and colloids

JF - Langmuir: the ACS journal of surfaces and colloids

SN - 0743-7463

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