NOVEL FORMULATION TECHNIQUE FOR BI-PHASE SYSTEMS FOR PRODUCT CUSTOMISATION
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Presented by: Ye Chen
There has been a rising demand for skin care products with innovative formats among which bi-phase product is one of the highly demanded types because of its distinctive and attractive appearance. Bi-phase in a skin care product usually consists of two transparent phases – an oil phase and a water phase. Color can be added to either or both phases to make the whole pack more appealing. The challenges remain to get a contrast two-phase system with one phase opaque and the other crystal clear because of the difficulty in controlling the emulsification. A formulation technique that gives a precise control of the emulsification level for a variety of oils, enabling a water-in-oil (W/O) emulsion floating on top of a clear water phase, generates a universal interest among formulators. It’s of even greater interest if such a format is customisable. A novel hydrophobically modified polyurethane, Polyurethane-62, has been developed to address such unmet needs. The polyurethane, without compromising the clarity of the lower water phase, provides an adequate emulsification capability for a W/O system, applicable to a wide range of oil components. Furthermore, the formulation process of such technique is simple and straightforward enough to empower product customisation or even personalisation by consumers themselves.
In this study, Polyurethane-62 was formulated into bi-phased systems with a variety of oils. A simple formulation process was established to test the robustness and flexibility of the system. Formulation variables, such as the concentration of the polymer, the selection of the emollient, pH and the electrolyte strength of the water phase, were investigated in terms of their influence on product appearance, separation profile, and storage stability.
Bi-phase formulations with a clear lower phase, an opaque upper phase, and a clear interface were successfully prepared when the use level of Polyurethan-62 is below its critical aggregation concentration (CAC). A three-step formulation process was set up and validated by different formulation variables and process parameters. Upon mixing or shaking, a milky lotion can be generated which separates again after standing still. The clarity of the lower water phase is dependent on the use level of Polyurethane-62. When the concentration of Polyurethan-62 is above its CAC, W/O emulsion is formed at the upper phase whereas O/W emulsion is created at the lower phase. Depending on the Formulations with higher use level of the polymer displays slower separation profile. On the other hand, faster separation is observed with formulations of a stronger electrolyte strength. pH of the water phase didn’t show a significant impact on the phase separation profile. In addition, results showed that the greater the surface tension difference is, the faster the separation becomes. As a W/O emulsion, the color of the upper opaque phase is in line with the color of the emollient, i.e. the yellower the emollient, the more yellowish the W/O emulsion is. Therefore, such bi-phase products can be customized in terms of color, contrast of appearance, separation profile, and possible additives. Furthermore, Polyurethane-62 offers a soft and powdery sensory upon application on skin, reducing the oily or greasy feel of a W/O emulsion.
A novel formulation technique using Polyurethane-62 is proposed with a comprehensive study of the impact of formulation variables. This study provides references that can be useful for developing appealing bi-phase products for skin care product customisation and personalisation.
In this study, Polyurethane-62 was formulated into bi-phased systems with a variety of oils. A simple formulation process was established to test the robustness and flexibility of the system. Formulation variables, such as the concentration of the polymer, the selection of the emollient, pH and the electrolyte strength of the water phase, were investigated in terms of their influence on product appearance, separation profile, and storage stability.
Bi-phase formulations with a clear lower phase, an opaque upper phase, and a clear interface were successfully prepared when the use level of Polyurethan-62 is below its critical aggregation concentration (CAC). A three-step formulation process was set up and validated by different formulation variables and process parameters. Upon mixing or shaking, a milky lotion can be generated which separates again after standing still. The clarity of the lower water phase is dependent on the use level of Polyurethane-62. When the concentration of Polyurethan-62 is above its CAC, W/O emulsion is formed at the upper phase whereas O/W emulsion is created at the lower phase. Depending on the Formulations with higher use level of the polymer displays slower separation profile. On the other hand, faster separation is observed with formulations of a stronger electrolyte strength. pH of the water phase didn’t show a significant impact on the phase separation profile. In addition, results showed that the greater the surface tension difference is, the faster the separation becomes. As a W/O emulsion, the color of the upper opaque phase is in line with the color of the emollient, i.e. the yellower the emollient, the more yellowish the W/O emulsion is. Therefore, such bi-phase products can be customized in terms of color, contrast of appearance, separation profile, and possible additives. Furthermore, Polyurethane-62 offers a soft and powdery sensory upon application on skin, reducing the oily or greasy feel of a W/O emulsion.
A novel formulation technique using Polyurethane-62 is proposed with a comprehensive study of the impact of formulation variables. This study provides references that can be useful for developing appealing bi-phase products for skin care product customisation and personalisation.