100% bio-based cationic conditioning agents by Inolex Amino Lipids

3 February 2020

Cationic surfactants are an important personal care ingredient class, particularly for hair conditioning applications. They improve hair combability in both the wet and dry state and can mitigate the effects of hair damage. The majority of cationic surfactants currently used in personal care formulations are quaternary ammonium species (quats), that have a permanent cationic charge independent of formulation pH, but are not 100% bio based and have potential for environmental and aquatic toxicity over their life cycle. Amino Lipids are the next evolution of high performing cationic ingredients that are derived exclusively from renewable sources. Their molecular design incorporates a cationic ammonium head group and biodegradable ester linkage, derived from naturally occurring amino acids, and a lipophilic alkyl tail group derived from vegetable fatty alcohols.

Advancement leads to challenges

Traditionally, formulation development with cationic surfactants was centered around these formulation-critical functional ingredients so there is a great deal of understanding about their surfactant self-assembly and subsequent liquid crystalline (LC) phase behavior and how that impacts formulation design. Additionally, the ingredient category has evolved to include multiple variations of quats each lending a specific performance benefit to hair. Amino Lipid technology is new to the beauty industry, introduced by Inolex in 2013 to bring the hair conditioning and emulsion stability benefits of cationic surfactants without the negative environmental impacts. To truly impact the category, the amino lipid technology platform must be expanded to encompass a range of measurable benefits. Development of a fundamental understanding of application behavior is needed to ensure personal care formulations can be developed that deliver key consumer benefits with this 100% bio-based multifunctional cationic ingredients.

Amino lipids structure can be altered for performance

The first-generation Amino Lipid was Brassicyl Isoleucinate Esylate (BIE) (Emulsense™ and Emulsense™ HC), based on the amino acid Isoleucine. Emulsense™ technology provided perceivable hair conditioning benefits and formulation stability with common emollients and oils. The second generation Amino Lipid, Brassicyl Valinate Esylate (BVE) (AminoSensyl™ HC and AminoSensyl™ SC) is based on the amino acid Valine. Formulations made with BVE showed greater stability, especially with high oil loads, and smoother textures, which can be related back to the amino acid head group difference (Figure 1).

**Figure 2. Anti-Breakage via Repeated Grooming of BVE and BIE Conditioner Formulations**

The different amino acid based head group structures lead to different surfactant self-assembly, and ultimately formulation performance. BVE (AminoSensyl™ technology) has a greater critical packing parameter as a result of having a smaller hydrophilic head group area. This allows BVE to form lamellar LC structures over a greater range of temperatures and concentrations. In formulations, lamellar LC structures are desired for their ability to create long-range order and structure which improves formulation stability and builds viscosity. Lamellar LC structures also give greater substantivity to skin and hair.

In addition to in-formulation benefits, Amino Lipid functional performance on hair varies with the change in amino acid head group structure. Conditioning performance and Hair strengthening benefits were evaluated for both AminoSensyl (BVE) and Emulsense (BIE) technologies using a wet combing evaluation and anti-breakage via repeated grooming evaluation, respectively (Figure 2). BVE provided a higher amount of conditioning and greater improvement in hair strength compared to BIE. Both technologies provided a significant reduction in wet comb force and breakage compared to the untreated control.

**Figure 1. Amino Lipid Technology, where R = CH3 for BVE and R = CH2CH3 for BIE. Alkyl chain is Brassica alkyl C18-C22, only C22 shown.**

The introduction of 100% biobased cationic ingredients provides the beauty industry with a step change advancement in performance and sustainability for a critical class of functional ingredients. The development of a multigenerational technology platform rooted in green chemistry design provides formulators with a complete toolbox to design high performance formulations for a range of consumer skin & hair types.

References:

1. Burgo, Rocco V. “Inolex Amino Lipids: 100% Natural and Eco-Friendly Breakthrough Hair Care Actives.” Premium Beauty News, Apr. 2, 2019.
2. Fevola, Michael J. “The Future of Cationic Surfactants: 100% Bio-Based Cationic Conditioning Agents via Green Chemistry.” Premium Beauty News, Jan. 29, 2019.
3. Holmberg, K, et al. Phase behaviour of concentrated surfactant systems. Ch. 3 in Surfactants and Polymers in Aqueous Solution, John Wiley & Sons Inc.: Hoboken, NJ, 2003, pp 67-95.
4.Evans, Trevor A. “Measuring Hair Strength, Part II: Fiber Breakage.” Cosmetics & Toiletries, 13 Jan. 2014.