Pivot away from hard to source emollients with Naatium Oleam

In the post-pandemic world, Unicare Ingredients has discovered that its Naatium Oleam technology not only stands up to the scrutiny of performance, but also to supply chain reliability. In this article, the company discusses why it is so easy to reformulate with its renewable hydrocarbons, providing formulators with options to pivot away from hard to source or exorbitant emollients. 

The function of an emollient in a formulation is primarily to soften the skin. Secondary and tertiary requirements are to provide a robust and stable base to carry active ingredients and other functional components. Some emollients act as functional components such as film formers or to provide sensorial effects. They might even offer different rates of absorbency.

Emollients are an important part of a formulation from both a cost and performance perspective, while sustainability is becoming an increasingly key issue. While formulators are often reluctant to move away from tried and tested solutions, they are facing increased pressure to consider carbon neutrality in their selection of ingredients. 

Rheology and tribology studies

Naatium Oleam is the leading green hydrocarbon technology available today. Having established a reputation with its customers for being a robust, cost-effective and easy to use emollient system suitable for low carbon footprint formulations, Unicare Ingredients sought to validate these claims through a detailed study of its performance in an emulsion system. This study would address the key concerns facing formulators when embarking on reformulation to a new emollient system. The first concern is changes to a products appearance. Secondly the stability and mobility of the product, as it is taken out of its packaging and presented to the consumer. Finally the performance of the product during application and post application (i.e. delivery of the functional and sensory attributes expected). 

The Centre for Industrial Rheology in the UK provides rheology and interfacial analysis, viscosity testing, powder flow and tribology studies among its many offerings. Unicare Ingredients retained the services of this world-class institute to develop a suitable test regime to provide comparative data against selected high performance natural and renewable emollient systems currently used and widely regarded as tried and tested. 

Naatium UV was benchmarked against a renewable Alkane (C13/C15), Naatium Baby against Squalane, and Naatium Nourish against Argan Oil. These tried and tested emollients were selected because they have similar viscosities to the comparative Naatium Oleam emollient. A sample of D5 Cyclomethicone was also included in the study to understand if there is a possible solution for replacing this silicone emollient in personal care products. A simple emulsion base was developed and treated with 10% of each emollient. The resulting sample was put through a series of rheology and tribology tests. 

Structural characteristics

Even before a customer touches a product the senses are engaged by observing its appearance. Does the product hold its shape? Or cling to the side of the bottle? Oscillatory testing helps quantify the bulk handling behaviour and rigidity resulting from structures created at the nano and microscale. The ‘first touch’ and under what conditions these structures yield are vital for consumer interaction as well as process and packaging design. The emulsions under investigation were subjected to low shear stress conditions, and low shear viscosity and yield stress data points were compiled which help define the products’ rigidity and mobility. 

The sensory experience, including flowability and rub-out, is dynamic and ephemeral. Some materials can engage consumers on multiple levels by changing their flow behaviour when one interacts with them. As cosmetic formulations are placed, spread and cleansed from the surface of skin or hair, complex flow materials such as emulsions can create sensory experiences that leave a lasting impression. Rheology studies were conducted at high shear conditions, which mimic the process of rub out. Here the key indicators were the viscosity profiles under high shear conditions. 

In the late stage of application where the product is spread ever thinner, the product lingers in multiple forms at oases in the miniature valleys and pits of the skin and hair, as a thin film masking surface roughness or even absorbed into the surface itself modifying its properties. Tribology profiling helps to quantify how the product has affected friction and lubrication properties and can be thought of as a signature unique to the two sliding surfaces and lubricant or emollient. Here the key indicator is the coefficient of friction. 

Low shear study comparison results

Figure 1: Low shear stress test data (Centre for Industrial Rheology UK)

In the comparison between Naatium UV and C13-C15 Alkane (see Figure 1), Naatium UV exhibited a higher yield stress indicating a more rigid structure has been formed by the interaction of the Naatium UV and the emulsion. On breaking the emulsion, the low shear viscosity of both the emulsions were the same indicating a similar initial spreading profile. 

Naatium Baby showed a lower yield stress than Squalane indicating that squalane forms a more complex rigid structure with the emulsion than Naatium Baby. Squalane also holds a higher low shear viscosity on breaking of the emulsion indicating that it spreads slower than Naatium Baby on initial application. The emulsion made with Naatium Nourish had a lower yield stress than the one with Argan Oil indicating that a more rigid structure was formed by the Argan Oil with the emulsion. On breaking the emulsion, Naatium Nourish showed a higher low shear viscosity indicating it is a slightly slower spreading emollient under low shear conditions. 

Cyclomethicone, Argan Oil and Naatium UV have similar yield stress profiles, indicating that a similar structure is formed with the emulsion. On breaking the emulsion, the low shear viscosity profiles are similar to Naatium Baby and Naatium Nourish, demonstrating that the Cyclomethicone holds the emulsion together more like a thicker emollient. 

High shear study comparison results

Figure 2: Low shear stress test data (Centre for Industrial Rheology UK)

Naatium UV and C13-C15 Alkane show similar high shear viscosity profiles (see Figure 2) indicating that the film formed on the surface during application is very similar. There is also a strong correlation on the friction coefficient, indicating a similar lubricity effect is imparted. Naatium Baby and Squalane have very similar high shear viscosity profiles, demonstrating that a similar film is formed on the surface during application. The Naatium Baby has a significantly better coefficient of friction indicating a better inherent lubricity than Squalane. 

Emulsions made with Naatium Nourish and Argan Oil show very similar high shear viscosity profiles, indicating a similar film is formed on the surface after ‘rub out’. Coefficient of friction is similar for both emulsions, indicating both emollients have a similar impact on lubricity, given they are of similar viscosity. 

The Cyclomethicone showed a higher high shear viscosity than any of the other emollients. This indicates that the emulsion formed by D5 forms a thicker film on the surface after application than any of the other emollients. The coefficient of friction was significantly higher than Naatium UV and C13-C15 Alkane (yet all three emollients have the same viscosity). This indicates that both C13-C15 Alakane and Naatium UV offer better lubricity and more glide than D5. 

Discussion and observations

Naatium Oleam renewable hydrocarbons make stable and robust emulsions and can offer the formulator a variety of outcomes. Light, mobile emulsions offering excellent lubricity can be achieved using Naatium UV. Naatium Baby provides superior lubricity to formulations and good film formation after rub out. Naatium Nourish gives a rich and substantive feel similar to that of Argan Oil and can be used as a cost-effective natural oil substitute or co-blending base for luxury natural oils such as Jojoba, Olive and Argan. 

It is clear that no single emollient tested can replace D5 Cyclopentasiloxane on its own. Naatium Baby maps well against D5 in all metrics apart from high shear viscosity. D5 is notoriously difficult to replace, however the data indicates that Naatium Baby offers a good replacement in most applications. When used in combination with Naatium UV and Naatium Nourish, it would cover most applications where Cylopentasiloxanes and Dimethicones are regarded as ‘irreplaceable’. 

Conclusion

The use of rheology and tribology is a growing and widely accepted science that enhances the understanding of cosmetic formulations in terms of their behaviour and performance, giving ingredients suppliers, brand owners and manufacturers of finished product valuable information that anticipates both product stability, aesthetics and performance. 

Naatium Oleam renewable hydrocarbon molecules have multidimensional properties. These cost-effective renewable cosmetic oils provide formulators with a solution to tackle the growing demand for sustainable biodegradable and high-performance products across the full spectrum of personal care categories. 

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