SKIN CARE
TABLE 1: OIL MIXTURE WITH FOUR EMOLLIENTS OF DIFFERENT POLARITY
INCI
Caprylic/Capric Triglyceride Squalane
Isopropyl myristate Dicaprylylether
wt. % 25 25 25
25
level due to its natural backbone – tara gum – which is particularly good in the presence of salt.
On the other hand, xanthan gum increases
even the viscosity when salt is added to the formulation. The reason for this is basically the same as for the higher viscosity at low pH (Figure 3). The biopolymer starts to behave more and more like a non-ionic thickener. While this seems to be positive at first glance, it has some negative effects on the skin feel, which will be covered later in the text.
Proofpoints in oil mixtures and serums Rheology modifiers play a crucial role in stabilizing cosmetic products. Without them, emulsions with high content of emollients, oils or mineral pigments would not be possible. Nevertheless, higher viscosity is often associated with higher stability. This is only partly true, as there are also sprayable emulsions available, where high viscosity is not a desired property. Viscosity plays a role, but deep down the
microstructure of a swollen polymer particle is the crucial factor in stabilizing high amounts of oils. Typical biopolymers build up their viscosity through the entanglement of the polymer chains. These highly flexible constructs are strongly hydrophilic and thus no stabilizing interactions exist with the hydrophobic oil. On the other hand, typical synthetic
polymers increase the viscosity of a formulation through the mechanism of microgel thickening (Figure 5). The polymer particles swell in water and become increasingly big until they touch the boundaries of the neighboring swollen
25 20 15 10 5 0
Figure 6: Maximum Oil Concentration stabilized by 1.0 wt.% of Aristoflex Eco T, xanthan gum, Aristoflex AVC or carbomer
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Figure 5: Thickening Mechanism of polymers via microgelation and how it stabilizes oils. A.) swollen microgel particles in a dilute state. B.) semi-dilute state with viscosity building up. C.) concentrated microgel with deformed microgel particles. D.) entrapping of oil droplets in the microgel
TABLE 2: COMPOSITION OF GOLDEN MILK SERUM. AN EMULSIFIER-FREE FORMULATION WITH HIGH AMOUNT OF OIL STABILIZED BY ARISTOFLEX ECO T
Phase Ingredients A Water
Glycerin 85%
B C
D E F Aristoflex Eco T Plantasens LS 6
Plantasens Olive LD SP ECO
G Nipaguard SCA H
Red Snow Epseama
INCI Aqua Glycerin
Disodium Succinate Sodium Hyaluronate
Propanediol (and) Water (and) Camellia Japonica Flower Extract Glycerin (and) Water (and) Laminaria Japonica Extract Aloe Barbadensis Leaf Juice Aqua
Oryza Sativa (Rice) Starch Caesalpinia Spinosa Gum/Ammonium AMPS crosspolymer
Olea Europaea (Olive) Fruit Oil (and) Simmondsia Chinensis (Jojoba) Seed Oil (and) Oleic Acid (and) Squalene (and) Tocopherol (and) Helianthus Annuus (Sunflower) Seed Oil
Coco-Caprylate/Caprate (and) Hydrogenated Olive Oil Unsaponifiables
Camellia Japonica Seed Oil
Sorbitan Caprylate (and) Benzyl Alcohol Perfume
Citric Acid / Sodium hydroxide
particle. Increasing the concentration further, the microgel particles deform and create a strong gel with a yield point. In this state, the gel is capable of stabilizing high amounts of oil, by entrapping the
Aristoflex Eco T■ Xanthan Gum ■ Aristoflex AVC ■ Carbomer■
w/w (%) Ad 100 2.00 0.15
0.50 1.00 1.00
20.00 0.80 0.80 0.80
3.00
1.50 1.50
0.30 q.s.
to pH 5.2
hydrophobic droplet between the swollen polymer particles. Although the interaction is not favourable, the oil droplet has nowhere to go as the force necessary to dislocate a swollen polymer particle is higher than the unfavourable interaction between the hydrophobic compound and the hydrophilic polymer particle. To demonstrate the performance of the tara
gum rheology modifier, an oil mixture (Table 1) was created that contains four emollients with different polarities that are commonly used in cosmetic applications. Various quantities of the oil mixture were then added together with the rheology modifier into water and mixed with an Ultraturrax for one minute. The resulting oil dispersion was then
stored over night at 20°C and considered to be stable if no destabilization phenomena (e.g. oil separation, creaming etc.) occurred. This test was repeated until it was possible to narrow down the exact value for the maximum oil concentration to be stabilized by 1.0 wt.% polymer. On the other hand, we were able to observe
that the synthetic rheology modifier Aristoflex AVC can stabilize up to 22% of oil mixture. This polymer’s outstanding performance makes
June 2023 PERSONAL CARE A B C D
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Max Oil Concentration %
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