Issue 34, 2021, Issue in Progress

Sol/gel transition of oil/water microemulsions controlled by surface grafted triblock copolymer dodecyl–PEO227–dodecyl: molecular dynamics simulations with experimentally validated interaction potential

Abstract

We studied a large range of identical spherical oil/water microemulsion (O/W-MI) volume fractions. The O/W-MIs are stabilized by cetylpyridinium chloride ionic surfactant (CpCl) and octanol cosurfactant and dispersed in salt water. We grafted different numbers of dodecyl–(polyEthylene oxide)227–dodecyl triblock copolymer that we note (n(D–PEO227–D)), where n varies from 0 to 12. We accomplished the grafting process by replacing a small amount of CpCl and octanol with the appropriate n(D–PEO227–D). The aim is to determine the interaction/structure relationship of the covered microemulsions. Precisely, we are interested in a quantitative investigation of the influence of volume fraction Φ, temperature (T), and n(D–PEO227–D) on the microemulsion sol/gel transition. To this end, we first study the uncoated microemulsion structure depending only on Φ. Second, we determine the coated microemulsions structure as a function of n(D–PEO227–D) for different Φ. Third, we examine the effect of temperature on the uncoated and coated microemulsion. We show that the sol/gel transition is controlled by the three main parameters, Φ, T, and n(D–PEO227–D). Accordingly, the uncoated microemulsion sol/gel transition, at ambient temperature, occurred for Φ ≃ 33.65%. By increasing Φ, the O/W-MIs show a glass state, which occurs, along with the gel state, at Φ ≃ 37% and arises clearly at Φ ≃ 60%. The coated O/W-MI sol/gel transition is found to be linearly dependent on n(D–PEO227–D) and takes place for Φ ≃ 26.5% for n(D–PEO227–D) = 12. Ordinarily, the decrease in temperature leads to gel formation of microemulsions for low Φ. Additionally, in this work, we found that the gelation temperature increases linearly with n(D–PEO227–D). Thus, the parameter n(D–PEO227–D) can control the sol/gel transition of the O/W-MIs at ambient temperature and moderate Φ.

Graphical abstract: Sol/gel transition of oil/water microemulsions controlled by surface grafted triblock copolymer dodecyl–PEO227–dodecyl: molecular dynamics simulations with experimentally validated interaction potential

Article information

Article type
Paper
Submitted
04 Apr 2021
Accepted
01 Jun 2021
First published
11 Jun 2021
This article is Open Access
Creative Commons BY license

RSC Adv., 2021,11, 20824-20835

Sol/gel transition of oil/water microemulsions controlled by surface grafted triblock copolymer dodecyl–PEO227–dodecyl: molecular dynamics simulations with experimentally validated interaction potential

M. Khatouri, M. Lemaalem, R. Ahfir, S. El Khaoui, A. Derouiche and M. Filali, RSC Adv., 2021, 11, 20824 DOI: 10.1039/D1RA02649F

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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