Preparation of Water-in-Oil Microemulsion from the Mixtures of Castor Oil and Sunflower Oil as Makeup Remover

Abstract

Cosmetics accumulated in facial skin are difficult to remove by ordinary cleansers because they normally contain highly waterproof ingredients. Therefore, development of makeup remover products is necessary for the efficient removal of cosmetics without irritation to the skin. Current commercial makeup removers are emulsions produced from mineral oil and water with surfactants sometimes cause allergies and acne. To overcome these problems, vegetable oils seem to be promising ingredients for makeup removers. In this study, such makeup removers were prepared as water‐in‐oil (w/o) microemulsion from a mixture of castor oil and sunflower oil at ratios from 1:9 to 5:5 and water with nonionic surfactants, Span®80 and Dehydol LS®TH. The remover candidates were selected with respect to transparency of emulsion and cleansing efficiency. As a result, an emulsion was prepared from a mixture of castor oil and sunflower oil with the ratio of 3:7, Dehydol LS®TH with 7 repeating units of ethylene oxide, and 7.0% (w/w) of water. It was found that the stability of transparency and a high cleansing efficiency were attributed to the hydrophilicity of the surfactant and castor oil. Dynamic light‐scattering analysis demonstrated that the emulsion consisted of nanoscale micelles, resulting in a microemulsion.

Full text

ORIGINAL ARTICLE
Preparation of Water-in-Oil Microemulsion from the Mixtures
of Castor Oil and Sunflower Oil as Makeup Remover
Nutthira Pakkang
1
· Yasumitsu Uraki
2
· Keiichi Koda
2
· Manit Nithitanakul
3
· Ampira Charoensaeng
3
Received: 21 January 2018 / Revised: 2 May 2018 / Accepted: 2 May 2018
© 2018 AOCS
Abstract Cosmetics accumulated in facial skin are diffi-
cult to remove by ordinary cleansers because they normally
contain highly waterproof ingredients. Therefore, develop-
ment of makeup remover products is necessary for the effi-
cient removal of cosmetics without irritation to the skin.
Current commercial makeup removers are emulsions pro-
duced from mineral oil and water with surfactants some-
times cause allergies and acne. To overcome these
problems, vegetable oils seem to be promising ingredients
for makeup removers. In this study, such makeup removers
were prepared as water-in-oil (w/o) microemulsion from a
mixture of castor oil and sunflower oil at ratios from 1:9 to
5:5 and water with nonionic surfactants, Span
®
80 and
Dehydol LS
®
TH. The remover candidates were selected
with respect to transparency of emulsion and cleansing effi-
ciency. As a result, an emulsion was prepared from a mix-
ture of castor oil and sunflower oil with the ratio of 3:7,
Dehydol LS
®
TH with 7 repeating units of ethylene oxide,
and 7.0% (w/w) of water. It was found that the stability of
transparency and a high cleansing efficiency were attributed
to the hydrophilicity of the surfactant and castor oil.
Dynamic light-scattering analysis demonstrated that the
emulsion consisted of nanoscale micelles, resulting in a
microemulsion.
Keywords Castor oil Sunflower oil Microemulsion 
Bio-based surfactant Makeup remover
J Surfact Deterg (2018).
Introduction
Cosmetics accumulated in facial skin are difficult to cleanse
sufficiently by cleansers or soaps, because of their high
waterproof ingredients. Cosmetics contain silicone resins or
hydrophobic polymers to enhance their waterproof proper-
ties. Therefore, the development of makeup remover prod-
ucts that are effective in the removal of cosmetics without
causing skin irritation is necessary (Kim et al., 2014). Cur-
rent commercial makeup removers are emulsions, and are
produced from mineral oil (a by-product obtained during
the distillation of petroleum), water, and surfactants. The
reason why mineral oils are used is that they are less greasy
and cheaper than vegetable oils (Chularojanamontri et al.,
2014). However, they sometimes cause allergic reactions
and acne. To overcome these problems, vegetable oils seem
to be promising ingredients for makeup removers. In this
study, such makeup removers were attempted to be pre-
pared from vegetable oils such as castor oil and
sunflower oil.
Castor oil, which is extracted from seeds of Ricinus com-
munis, differs from other vegetable oils in that it is rich in a
unique carboxylate, ricinoleate (Ayuba et al., 2017). Ninety
percent of the total triacylglycerols are triricinoleate. The
Supporting information Additional supporting information may be
found online in the Supporting Information section at the end of the
article.
*Yasumitsu Uraki
uraki@for.agr.hokudai.ac.jp
1
Graduate School of Agriculture, Hokkaido University, Sapporo,
060-8589, Japan
2
Research Faculty of Agriculture, Hokkaido University, Sapporo,
060-8589, Japan
3
The Petroleum and Petrochemical College, Chulalongkorn
University, Bangkok, 10330, Thailand
J Surfact Deterg (2018)
J Surfact Deterg (2018)
DOI 10.1002/jsde.12189

ricinoleate moiety has a hydroxy group at the C-12 posi-
tion, which makes castor oil more polar than other vegeta-
ble oils (Salimon et al., 2011; Shombe et al., 2016). The
hydrophilicity may be advantageous for the formation of a
remover emulsion. However, castor oil also has a disadvan-
tage; it has high viscosity (Grace et al., 2017). On the other
hand, sunflower oil shows low viscosity because it has two
double bonds and no hydroxy group in a carboxylate moi-
ety and is widely used in cosmetics for emollient skin care
(Neelamegam and Krishnaraj, 2011). In this study, microe-
mulsions for makeup removers are prepared from mixtures
of castor oil and sunflower oil using a nonionic surfactant.
In the remover, transparency is an important factor. There-
fore, a microemulsion with micelle diameter ranging from
10 to 50 nm is suitable (Slomkowski et al., 2011). In the
cosmetic removal process, oil-based cosmetics are dissolved
and dispersed in the microemulsion by rubbing the skin. In
detail, the water-in-oil (w/o) micelle structure in the microe-
mulsion is disrupted by rubbing force, causing the surfactant
and oil of the remover to contact easily with the cosmetics
on the skin. In the rinsing process with water, the surfactant
and oil combined with cosmetic encounter water to form oil-
in-water (o/w) micelles (Suzuki et al., 1992) (Fig. 1).
In addition, microemulsions are not only used as
removers in the cosmetic industry but are also applied to
remove waste oils in the oil industry (Dantas et al., 2004;
Tadros, 2013; Wei et al., 2013).
Surfactants can be classified into four groups on the basis
of the electric charge: anionic, cationic, amphoteric, and
nonionic surfactants. In the cosmetic industry, anionic, cat-
ionic, and amphoteric surfactants have a drawback: they
cause irritation (Corazza et al., 2010; Effendy and Maibach,
1995; Löffler and Happle, 2003); however, nonionic surfac-
tants cause very little irritation. Moreover, Effendy and
Maibach (1995) reported that natural-based nonionic sur-
factants have excellent solubilizing properties for plant oils.
In this study, two nonionic surfactants were used for pre-
paring a microemulsion. One was sorbitan monooleate
(Span
®
80) produced from polyethoxylated sorbitan and
oleic acid (Becker, 2015), and the other one was the so-
called fatty alcohol ethoxylates with 2, 5, and 7 repeating
units of ethylene oxide (EO units) (Dehydol LS
®
TH),
which are abbreviated as laureth-2, -5, and -7, respec-
tively (Fig. 2).
In this article, remover candidates were selected from the
100 emulsions prepared by mixing castor oil and sunflower
oil in various ratios, with four nonionic surfactants and dif-
ferent water contents with respect to transparency and
cleansing efficiency of emulsions. The micelle structure
and surface charge of the candidate emulsions were investi-
gated by means of dynamic light scattering (DLS) and zeta
(ζ) potential.
Experimental
Materials
Castor oil (C) was purchased from Hong Huat Co. (Bangkok,
Thailand). Sunflower oil (S) was purchased from Thanakorn
Vegetable Oil Product Co., Ltd. (Samutprakarn, Thailand).
Sorbitan monooleate (Span
®
80) was purchased from Sigma-
Aldrich Chemical (St. Louis, MO, USA). Fatty alcohol
ethoxylates with different EO units (fatty alcohols C12–14
with 2 EO units, 5 EO units, and 7 EO units) in solution as a
liquid surfactant (>99.7%) were kindly supplied by Thai
Ethoxylate Co. Ltd. (Rayong, Thailand). Red lipstick (matte
type) was purchased from Revlon, Inc. (USA), as a typical
sample of cosmetics. A commercial cleansing oil remover
(Fasio
®
perfect cleansing oil) was purchased from KOSÉ
Corporation (Japan). All materials were used as received.
Methods
Preparation of Remover Candidates
Castor oil and sunflower oil were mixed at various ratios of
1:9, 2:8, 3:7, 4:6, and 5:5. Each of the four types of liquid
surfactant, containing either fatty alcohol ethoxylates (with
2, 5, or 7 EO units), or sorbitan monooleate, was then
added to the mixed oil in a vial. The volume ratio of the
surfactant solution to the mixed oil was fixed at 2:3. The
surfactant–oil mixture was further mixed to give a suspen-
sion by gentle shaking for 15 min. Then, distilled water
was added dropwise to the suspension in the vial, to yield
the desired water content (2, 4, 6, 8, and 10% (w/w) on the
total mixture). The mixture was shaken again for 15 min,
Fig. 1 The mechanism of the removal process of lipstick (cosmetics) and a rinsing process with water
J Surfact Deterg
J Surfact Deterg (2018)

and the mixture in the vial was photographed. All suspen-
sions (100 samples in total; with five different mixed ratios
of oils, four types of surfactants, and with five different
levels of water content) as remover candidates were stored
in sealed containers to avoid evaporation at room tempera-
ture for 1 month. After the 1-month storage, another photo-
graph was taken. The maximum water contents to form a
single-phase emulsion (e.g., between 6% [single phase] and
8% [phase separated]) was roughly estimated by visual
confirmation.
To determine the precise maximum water content to
form single-phase emulsion, an emulsion with the roughly
estimated maximum water content was selected (e.g., 6%).
When the emulsion did not undergo phase separation, water
was added incrementally to the emulsion. The addition of
water was continued at a water content interval of 0.1%
(w/w) until the water content reached the maximum water
content to maintain single-phase emulsion and those resul-
tant emulsions were gently shaken for 15 min. After
1-month storage at room temperature (25 2C), the
maximum water content to allow forming a single-phase
emulsion was visibly determined.
Rubbing Test
The efficiency of cosmetic cleansing was evaluated using
porcine skin using a method, modified from the previously
reported method (Davies et al., 2015; Walters et al., 2012).
Porcine skin was excised from the belly area and used
within 24 h of preparation. The red lipstick (0.03 g) was
spread on porcine skin (Herron, 2009) for a length of
2.5 cm. One gram of the remover candidate suspension
was dropped on the lipstick part of the skin. The skin was
rubbed with two fingers until the lipstick was dissolved in
the remover. The number of rubbing till all lipstick dis-
solved in the remover was recorded as a measure of cleans-
ing performance of the remover. Water was added
dropwise from a burette to the skin with rubbing until all
materials on the skin disappear. The dropped volume of
water at the disappearance of all materials was recorded as
a measure of cleansing performance of the remover. Exper-
iments were performed in triplicate in each sample at room
temperature (25 2C).
Measurements of DLS and Zeta Potential
After the rubbing test, the remover candidates were stored
at room temperature (25 2C) for 1 month until the
measurement of DLS analysis. These measurements were
performed at 25 C on a Zetasizer Nano ZS (Malvern
Instruments, UK) equipped with a helium–neon laser at
633 nm. Samples were sonicated for 5 min and left stand-
ing for 15 min. Each sample (1.5 mL) was inserted into a
folded capillary cell (DTS1070, Malvern Instruments).
Fig. 2 Structure of (a) castor oil, (b) sunflower oil, (c) fatty alcohol ethoxylate with 2, 5, and 7 EO units (only laureth [C12] series are shown),
and (d) sorbitan monooleate
J Surfact Deterg
J Surfact Deterg (2018)

The parameters in Zetasizer
®
software were set as follows:
material reflective index, 1.330; dispersant reflective index,
1.465; viscosity 49.14 cP; duration used, 10 s.
Results and Discussion
Key factors of makeup removers are transparency and
cleansing performance. First, transparency of the emulsions
prepared from the mixture of vegetable oil and nonionic
surfactants was judged from visible inspection to select the
remover candidates among the tested specimens.
In general, a high content of surfactant in removers is
expected to retain single-phase emulsion with a high water
content (Watanabe et al., 2004). However, our target is to
prepare makeup removers with a higher ratio of oil and
water to surfactant for better utilization of vegetable oil,
especially castor oil. In our preliminary tests including the
conditions to use cosurfactants, we found that the makeup
Fig. 3 Images of emulsion and microemulsion in a system of castor oil: sunflower oil (C:S) (3:7) with water content from 2, 4, 6, 8, and 10%
(w/w) and (a) Span
®
80, (b) laureth-2, (c) laureth-5, (d) laureth-7 just after preparation at room temperature (25 2C)
Table 1 Maximum water content of microemulsion to maintain trans-
parency after 1-month storage
Surfactant type C:S
a
Maximum of water content [% (w/w)]
Rough estimate value Precise value
Span 80 1:9 <2 –
2:8 <2 –
3:7 <2 –
Laureth-2 1:9 <2 –
2:8 <2 –
3:7 <2 –
Laureth-5 1:9 6 5.7
2:8 6 6.0
3:7 6 6.2
Laureth-7 1:9 6 5.9
2:8 6 6.5
3:7 6 7.0
a
C:S is the ratio of castor oil: sunflower oil.
Fig. 4 The phase diagrams of laureth-7 at C:S = 3:7 and various water
contents at room temperature (25 2C). Gray area shows a trans-
parent microemulsion with single phase
J Surfact Deterg
J Surfact Deterg (2018)

remover with a volume ratio of the surfactant to the mixed
oil of 2:3 could contain the highest water content among
the conditions where less than 50% (w/w) of surfactant was
used (Fig. S1, Supporting information). To avoid checking
all possible combinations of water, surfactant, oil mixture,
the conditions at the fixed surfactant-to-oil ratio of 2:3 were
used thereafter.
The increased ratio of castor oil to sunflower oil was
thought to be favorable because castor oil is more hydro-
philic than sunflower oil to keep the water content of
removers at a high level. However, in our preliminary tests,
the conditions of the castor oil ratio of 4:6 and higher for
any types of surfactants gave cloudy emulsion to result in
phase separation eventually (Fig. S2). Therefore, we chose
the condition of the ratio of 3:7, thereafter, which contained
the highest amount of castor oil among the conditions tested.
Formation of Transparent Microemulsions
Photo images of the emulsion examples just after prepara-
tion are shown in Fig. 3. In Fig. 3a, the emulsions prepared
from sorbitan monooleate (Span
®
80) mixed with water and
castor oil:sunflower oil (C:S) = 3:7 were opaque. More-
over, the opaque emulsions were obtained from sorbitan
monooleate mixed at other ratios of (C:S) (1:9, 2:8, 4:6,
and 5:5) and any water content. Therefore, Span
®
80 did
not give any transparent emulsions when these vegetable
oils were used.
Figures 3b, c, and d reveal that all emulsions prepared at
a ratio of C:S = 3:7 and laureth groups are transparent. How-
ever, all the emulsions prepared from laureth-2 [Fig. 3b
series] became two phases after 1-month storage [Fig. S3a].
On the other hand, the emulsions prepared from laureth-5
[Fig. 3c] and laureth-7 [Fig. 3d] at C:S = 3:7 and 2–6%
(w/w) of water contents retained transparency even after
1-month storage, but the emulsions prepared at 8–10%
(w/w) of water contents had already shown two phases after
1-month storage [Fig. S3b, c]. Similarly, the transparent
emulsions were obtained from laureth-5 and laureth-7 at C:
S = 1:9 and 2:8 and 2–6% (w/w) of water contents, but their
emulsions prepared at 8–10% (w/w) of water content under-
went phase separation to give two phases after 1-month stor-
age. Furthermore, emulsions prepared from C:S = 4:6 and
5:5 at any water content were opaque just after preparation.
Thus, the laureth-5 and laureth-7 under the condition of C:
S = 1:9, 2:8, and 3:7 and 2–6% (w/w) of water contents
were chosen to be remover candidates, supposing that trans-
parent emulsions should be microemulsions.
Before the rubbing test, we predicted that the excellent
cleansing efficiency was obtained with increasing water
content in the emulsions in accordance with previous report
(Klier et al., 1997). Thereby, maximum water content to
form a single-phase emulsion was investigated by means of
water titration to the oil mixture. The maximum concentra-
tions for laureth-5 and -7 at various C:S ratios are listed in
Table 1. In addition, the phase diagram of three compo-
nents, laureth-7, C:S = 3:7, and water, are shown in Fig. 4.
When increasing the castor oil ratio in the oil mixture, the
maximum water content also increases. This phenomenon
might be caused by the hydrophilic interaction between
castor oil and water due to the fact that castor oil is more
hydrophilic than sunflower oil as mentioned above.
Fig. 5 Number of rubbing for cleansing the red lipstick at room temperature (25 2C)
Fig. 6 Volume of water used for cleansing the red lipstick at room temperature (25 2C)
J Surfact Deterg
J Surfact Deterg (2018)

Cleansing Efficiency
Cleansing efficiency of the emulsions prepared from
laureth-5 and -7 was evaluated in terms of the number
of rubbing and the volume of water used for complete
cleansing of lipstick. The average number of rubbing
and the average volume of water used of laureth-7 series
were smaller than those of a commercial cleansing oil
remover as a positive control (Figs. 5–6). Although the
number of rubbing of laureth-5 series was also smaller
than that of the commercial remover, the volume of used
water for laureth-5 at C:S = 1:9 and at the water content
of 5.7% (w/w) was larger than that of the commercial
remover.
In both cases of laureth-5 and -7 series, when the castor
oil ratio in the oil mixture was increased, the number of
rubbing and the volume of used water were decreased.
Consequently, the emulsion prepared from laureth-7 at C:
S = 3:7 and 7.0% (w/w) of water content was the best can-
didate for the remover because the number of rubbing and
the volume of used water were the smallest. Thus, the
hydrophilicity of castor oil enabled a high water content in
an emulsion and positively affected the cleansing
efficiency.
Fig. 7 The micelle-size distribution in microemulsions at castor oil: sunflower oil ratio of (C:S) = 3:7 with (a) laureth-2 and 2.0% (w/w) of water,
(b) laureth-5 and 6.2% (w/w) of water, (c) laureth-7 and 7.0% (w/w) of water
J Surfact Deterg
J Surfact Deterg (2018)

Particle Sizing and Zeta (ζ) Potential
DLS and ζpotential of the transparent emulsions prepared
from laureth-2, −5, and −7 at C:S = 3:7 and their corre-
sponding maximum water content [2.0, 6.2, and 7.0%
(w/w), respectively] were measured on a DLS analyzer to
clarify the micelle size and the surface charges of
micelles (Fig. 7).
The number-average micelle sizes of laureth-5 and -7
were 17.62 and 28.91 nm, respectively. This suggested that
the emulsions were microemulsions. Therefore, the trans-
parency was caused by nanoscale micelles.
As aforementioned, although the emulsion of laureth-2
was transparent just after preparation, the emulsion exhib-
ited phase separation during 1-month storage. The micelle
size was found to be quite large (2627 nm), indicating an
emulsion rather than a microemulsion.
The zeta potential was decreased with increasing in the
water content, as shown in Fig. 8. The negative potential
was caused by HCO
3
−
generated from the carbon dioxide
dissolved in water (Chaplin, 2009). Accordingly, a high
absolute value of zeta potential was attributed to the water
content. Consequently, these negative charges might con-
tribute to the prevention of microemulsion aggregation,
resulting in a long-term stability of microemulsion prepared
from laureth-7.
Conclusions
In this article, a microemulsion prepared from laureth-7, a
mixture of castor oil and sunflower oil with a ratio of 3:7,
and 7.0% (w/w) of water content was selected as the best
makeup-remover candidate among the tested emulsions.
The following conclusions were drawn.
1. Fatty alcohol ethoxylate series were a better surfactant
than sorbitan monooleate for the preparation of a
makeup remover.
2. The longer repeating unit of EO in fatty alcohol ethox-
ylate caused high cleansing efficiency.
3. The higher ratio of a castor oil in the oil mixture, at an
acceptable maximum content to maintain transparency
of microemulsions (at a surfactant-to-oil mixture ratio
of 2:3 and at a castor oil-to-sunflower oil ratio of 3:7),
was favorable to maintain a higher water content and
caused a higher cleansing efficiency. This function was
attributed to the hydrophilicity of castor oil.
4. From the ζpotential measurement, a high water con-
tent in the emulsion brought about surface negative
charge of the emulsion.
Acknowledgements The authors are grateful for the support from
the Thai Ethoxylate Co. Ltd., Thailand.
Conflict of Interest The authors declare that they have no conflict
of interest.
References
Ayuba, L., Agboire, S., Gana, A. K., Ishaq, M., Aliyu, U.,
Affiniki, G., & Manjang, J. I. (2017) Efficacy of castor oil in the
control of throat, skin and enteric bacteria. Advances in Food Sci-
ence and Engineering,1:95–99. https://doi.org/10.22606/afse.2017.
13001
Becker, L. C. (2015). Final amended report of the safety assessment
of polysorbates as used in cosmetics. The CIR Expert Panel.
Retrieved from https://www.cir-safety.org/sites/default/files/
polysorbates.pdf
Chaplin, M. (2009) Theory vs experiment: What is the surface charge
of water? Water,1:1–28. https://doi.org/10.14294/water.2009.2
Chularojanamontri, L., Tuchinda, P., Kulthanan, K., & Pongparit, K.
(2014) Moisturizers for acne: What are their constituents? The
Journal of Clinical and Aesthetic Dermatology,7:36–44.
Corazza, M., Lauriola, M. M., Zappaterra, M., Bianchi, A., &
Virgili, A. (2010) Surfactants, skin cleansing protagonists. Journal
of the European Academy of Dermatology and Venereology,24:
1–6. https://doi.org/10.1111/j.1468-3083.2009.03349.x.
Dantas, N. A. A., de Castro, D. T. N., & Alencar, M. M. C. (2004)
Evaluation and optimization of chromium removal from tannery
effluent by microemulsion in the Morris extractor. Journal of Haz-
ardous Materials,114:115–122. https://doi.org/10.1016/j.jhazmat.
2004.07.007
Davies, D. J., Heylings, J. R., Mccarthy, T. J., & Correa, C. M.
(2015) Toxicology in vitro development of an in vitro model for
studying the penetration of chemicals through compromised skin.
Toxicology in Vitro,29:176–181.
Effendy, I., & Maibach, H. I. (1995) Surfactants and experimental irri-
tant contact dermatitis. Contact Dermatitis,33:217–225. https://doi.
org/10.1111/j.1600-0536.1995.tb00470.x
Grace, S. A., Sutton, A. M., Abraham, N., & Armbrecht, E. S. (2017)
Presence of mast cells and mast cell degranulation in scalp biopsies
of telogen effluvium. International Journal of Trichology,9:25-29.
https://doi.org/10.4103/ijt.ijt_43_16
Herron, A. J. (2009). Pigs as dermatologic models of human skin dis-
ease. In Proceeding of the ACVP/ASVCP Concurrent Annual Meet-
ings, 30 October–3 November, Baltimore, MD, USA.
Kim, E. J., Kong, B. J., Kwon, S. S., Jang, H. N., & Park, S. N.
(2014) Preparation and characterization of w/o microemulsion for
Fig. 8 ζpotential values of castor oil and sunflower oil ratio of 3:7
(C:S ratio) with laureth-2, -5, and −7 and various water contents
J Surfact Deterg
J Surfact Deterg (2018)

removal of oily make-up cosmetics. International Journal of Cos-
metic Science,36:606–612. https://doi.org/10.1111/ics.12163.
Klier, J., Strandburg, G. M., & Tucker, C. J. (1997). High water con-
tent, low viscosity, oil continuous microemulsions and emulsions,
and their use in cleansing applications (Patent No. 5,597,792).
U.S. Patent and Trademark Office.
Löffler, H., & Happle, R. (2003) Profile of irritant patch testing with
detergents: Sodium lauryl sulfate, sodium laureth sulfate and alkyl
polyglucoside. Contact Dermatitis,48:26–32. https://doi.org/10.
1034/j.1600-0536.2003.480105.x
Neelamegam, P., & Krishnaraj, S. (2011) Estimation of liquid viscosi-
ties of oils using associative neural networks. Indian Journal of
Chemical Technology,18:463–468.
Salimon, J., Nallathamby, N., Salih, N., & Abdullah, B. M. (2011)
Synthesis and physical properties of estolide ester using saturated
fatty acid and ricinoleic acid. Journal of Automated Methods and
Management in Chemistry,2011:1–4. https://doi.org/10.1155/
2011/263624
Shombe, G. B., Mubofu, E. B., Mlowe, S., & Revaprasadu, N. (2016)
Synthesis and characterization of castor oil and ricinoleic acid
capped CdS nanoparticles using single source precursors. Materials
Science in Semiconductor Processing,43:230–237. https://doi.
org/10.1016/j.mssp.2015.11.011
Slomkowski, S., Alemán, J. V., Gilbert, R. G., Hess, M., Horie, K.,
Jones, R. G., …Stepto, R. F. T. (2011) Terminology of polymers
and polymerization processes in dispersed systems (IUPAC recom-
mendations 2011). Pure and Applied Chemistry,83:2229–2259.
https://doi.org/10.1351/pac-rec-10-06-03
Suzuki, T., Nakamura, M., Sumida, H., & Shigeta, A. (1992) Liquid
crystal make-up remover: Conditions of formation and its cleansing
mechanisms. Journal of the Society of Cosmetic Chemists,43:
21–36.
Tadros, T. F. (2013) In T. F. Tadros (Ed.), Emulsion Formation, Sta-
bility, and Rheology. Weinheim, Germany: Wiley-VCH Verlag
GmbH & Co. KGaA. https://doi.org/10.1002/9783527647941.ch1
Walters, R. M., Mao, G., Gunn, E. T., & Hornby, S. (2012) Cleansing
formulations that respect skin barrier integrity. Dermatology
Research and Practice,2012:1–9. https://doi.org/10.1155/2012/
495917
Watanabe, K. W., Noda, A. N., Masuda, M. M., & Nakamura, K. N.
(2004) Bicontinuous microemulsion type cleansing containing
comparison of solubilization behavior of cyclic siloxane with Polar
oil. Journal of Oleo Science,53:537–546. https://doi.org/10.5650/
jos.53.537
Wei, H., He, H. J., Wang, Z. H., Ma, J., Zhang, X., & Shan, H. X.
(2013) Study on oil-base drilling cuttings cleaning technology
using microemulsion cleaner. Journal of Xi’an Shiyou University
(Natural Science),28:90–94.
J Surfact Deterg
J Surfact Deterg (2018)