SILICONE EMULSIFIERS: NEW DEVELOPMENTS
AND FORMULATION CONCEPTS
ISABELLE VAN REETH , BAO R. XINYAN , BÉATRICE DURAND ,
2
3
2
INGRID VERVIER , YASUHIRO KANETA , CINDY DELVALLÉ
1
Dow Corning (Shanghai) Co., Ltd., Shanghai, China
2
Dow Corning Europe S.A., Seneffe, Belgium
3
Dow Corning Toray, Chiba, Japan
Abstract
Carrier choice also can impact particle size.
Silicone emulsifiers for water-in-oil systems provide a
smooth and silky feel, wash-off resistance, substantivity,
improved barrier properties, emolliency, and ease
of use.
 PEG/PPG-19/19
dimethicone in cyclopentasiloxane,
a volatile silicone (below left).
 PEG/PPG-19/19
dimethicone in isoparaffin, a volatile
organic (below right).
The newest silicone emulsifiers offer broader options
for the oil phase and increase textural possibilities.
Earlier work identified primary parameters affecting
formulation viscosity and stability: water-to-silicone/oil
ratio, mixing process, emulsifier level, external phase
viscosity, and presence or lack of coemulsifier [1].
In this study, impact of emulsifier structure and carrier
on particle size and the influence of oil phase density
on final emulsion viscosity are reviewed in more detail.
In addition, new formulation concepts illustrate broader
emulsifier capabilities:
 Stabilization
and delivery of fragile actives such as
vitamin C in a cream with high moisturization potential
and a nongreasy, smooth feel.
 Stabilization
2
of low-viscosity fluid foundation.
Introduction
Recent studies gave recommendations for formulating
with water-in-silicone+oil formulations [1]:
The (glycerin+water)-in-silicone emulsion showed
sensory improvements compared to pure glycerin.
 Faster
absorption
 Reduced
gloss
 Powdery
feel provided by the silicone elastomer
Tackiness before absorption
(99.9%)
Tackiness after absorption
(99.9%)
 Most
of the oil phase is dimethicone, 2 cSt;
therefore, the carrier of the emulsifier itself is
somewhat diluted.
 Impact
on particle size might be explained by
difference in availability for the emulsifier when
delivered in a silicone or an organic carrier.
Impact of oil phase density on emulsion viscosity
Moisturizing properties of the high level (glycerin+
water)-in-silicone emulsion are equivalent to those of
pure glycerin.
 Specific
gravity of isododecane = 0.74; 20 g = 27 mL.
Specific gravity of cyclopentasiloxane = 0.95; 20 g =
21 mL.
250
Moisturization Increase
vs. Untreated Skin (%)
1
1
 Direct
replacement would affect oil/water ratio,
resulting in lower viscosity for final emulsion.
 When
changing oil phases, consider density and
modify oil/water phase ratio to obtain viscosity that
ensures optimum stability.
of the oil phase (i.e., polarity and compatibility
with the emulsifier) also impacts viscosity and
stability.
200
150
100
50
0
Two novel formulation concepts were developed based
on the new silicone emulsifier technologies.
The current work provides additional insight on
parameters that influence final emulsion characteristics
and support new formulation concepts.
Materials and Methods
New silicone polyethers evaluated:
 PEG/PPG-19/19
dimethicone (and) C13-16
isoparaffin (and) C10-13 isoparaffin
 PEG-10
Glycerin-in-silicone systems for vitamin C
stabilization
 Until
recently, stability and poor aesthetics limited
the success of this approach.
 New
silicone polyethers, such as PEG-10 dimethicone
and PEG/PPG-19/19 dimethicone, allow formulation
of polyol-in-silicone emulsions with stable viscosity.
 High
level of silicone elastomer in the emulsions gives
good sensory profiles.
dimethicone
Glycerin-in-Silicone Emulsion
Existing materials:
 Cyclopentasiloxane
dimethicone
 Cyclopentasiloxane
crosspolymer
(and) PEG/PPG-19/19
(and) PEG-12 dimethicone
Summary of procedure:
recorded with rheometer after one day and
one month.
Ingredients
PEG-10 Dimethicone or PEG/
PPG-19/19 Dimethicone
Caprylyl Methicone
Silicone Elastomer Blend
L-Ascorbic Acid
Glycerin
Water
Wt %
3.5 to 4.5
10.0
4.0 to 15.0
1.5 to 10.0
59.0 to 80.0
to 100.0
 Viscosity
 Visual
stability recorded at RT and 40°C after one
day; one week; one, two and three months.
 Emulsions
observed under light-reflecting microscope
at one day and one month.
Stability of Systems Containing 10% Vitamin C
as a Function of Water Content (50°C)
Glycerin-in-Silicone
Emulsion
(Glycerin+Water)in-Silicone
Emulsion
Water-in-Silicone
Emulsion
After 3 days
 For
emulsions containing fragile active, stability
observed at 50°C after one month.
 Vitamin
C stability data further evaluated using
HPLC (mobile phase; trifluoroacetic acid/methanol;
95/5; flow 1.5mL/min; temperature: 22°C).
Conditions used to evaluate potential impact of emulsifier
structure and carrier on emulsion particle size:
After 1 month
 Formulation:
W/Si ratio 80/20, emulsifier level
1% (nondispersed), silicone phase composed of
dimethicone, 2 cSt.
 Particle
Results and Discussion
Molecular weight of the emulsifier can affect particle
size.
 PEG-10
dimethicone (below left) is a low molecular
weight silicone polyether (SPE).
 PEG-12
dimethicone crosspolymer (below right),
is a high molecular weight SPE with a cross-linked
structure.
120
180
240
300
360
Glycerin-in-Silicone
Glycerin
Foundations
PEG-10 dimethicone combines very good pigment
dispersion properties with the ability to make lowviscosity stable emulsions.
Liquid Foundation with PEG-10 Dimethicone
Ingredients
PEG-10 Dimethicone
Dimethicone
Caprylyl Methicone
Lauryl PEG/PPG-18/18 Dimethicone
Silica Silylate
Water
Glycerin
Sodium Chloride
Preservative
Pigment Mix
Caprylyl Methicone
Fragrance
Wt %
8.0
7.6
7.6
0.8
0.3
51.0
5.0
1.0
1.0
12.0
5.4
0.3
PEG/PPG-19/19 dimethicone gives a creamier, gellike foundation, still with good spreading for optimum
coverage and a light, smooth feel.
Creamy Foundation with PEG/PPG-19 Dimethicone
Ingredients
PEG/PPG-19/19 Dimethicone (and) C13-16
Isoparaffin (and) C10-13 Isoparaffin
C30-45 Alkyldimethylsilyl
Polypropylsilsesquioxane
Wt %
Caprylyl Methicone
Ethyhexyl Methoxycinnamate
Silica Silylate
Water
Glycerin
Sodium Chloride
Actives
Preservatives
Pigment Mix
Caprylyl Methicone
Fragrance
2.0
2.0
0.3
54.0
5.0
1.0
2.0
1.0
9.0
14.9
0.3
6.0
2.5
Conclusions
 Visual
results were confirmed by HPLC.
 The
(glycerin+water)-in-silicone emulsion still
contained a high level of nondegraded vitamin C,
more than expected based on visual evaluation.
10
Vitamin C Content (%)
size measurements: emulsion diluted at
3.3% in dimethicone, 2 cSt. Observed with transmitted
illumination on Zeiss Axioplan™ microscope, 100x.
60
Time (min)
 Nature
New formulation concepts
30
8
This study provides a better understanding of the link
between emulsifier structure and composition and
performance in emulsions, allowing formulators to take
full advantage of emulsion formulating capabilities.
Extended formulation possibilities:
A
high-level (glycerin+water)-in-silicone system
for stabilizing up to 10% vitamin C, while keeping
good sensory characteristics and high moisturizing
performance.
 Liquid
to creamy foundations with high pigment load.
6
4
2
0
Glycerin-in-Silicone (Glycerin+Water)-inEmulsion
Silicone Emulsion
Room Temperature
Water-in-Silicone
Emulsion
50°C
References
1. Durand, B., Newton, J., Delvallé, C., Vervier, I., and Masse, S., New Formulation
Capabilities Using Water-in-Silicone Emulsions, SCC Scientific Seminar, Chicago, IL,
June 4-5, 2009.
Dow Corning is a registered trademark of Dow Corning Corporation.
All other trademarks are property of their respective owners.
dowcorning.com/personalcare