Enhancing the conditioning performance of cationic amino lipids by formulating for optimized lamellar gel networks
Podium 28
Presented by: Brittany Pease
Introduction
Cationic amino lipids have been established as a more sustainable alternative to traditional cationic surfactants due to their 100% renewable origin and superior human and environmental safety profiles. Unlike traditional quaternary ammonium cationic surfactants, i.e. “quats”, used in hair care, amino lipids
derive their cationic character from protonation of their primary amine moieties that are derived from natural amino acids. Like other long chain cationic surfactants, amino lipids such as Brassicyl Valinate Esylate (BVE) are typically formulated with long chain fatty alcohols to yield lamellar liquid crystalline (LC) systems that demonstrate significant viscosity and yield value. These LC systems can stabilize hydrophobic oil phases and exhibit strong substantivity to hair, making them highly effective as rinse-off and leave-on hair conditioning products. The present study will examine the effects of fatty alcohol selection and use level on lamellar gel network (LGN) formation and properties when formulating with BVE and provide a comparison to the industry benchmark for conditioning performance, Behentrimonium Chloride (BTAC), a long chain quat.
Methods
Cationic surfactants, including BVE and BTAC, are formulated with varying ratios of different fatty alcohols to determine the effects of C-chain length and blend ratio on the LC phase behavior, LGN properties, and hair conditioning performance. LC structure and morphology are characterized using polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and cryo scanning electron microscopy (CSEM), and rheological analysis is used to quantify macroscopic fluid properties. Hair conditioning performance is assessed on hair tresses in terms of comb force reduction (wet/dry) and resistance to breakage, and by consumer perception during home-use.
Results
BVE is an amino lipid with a heterogenous alkyl chain length distribution comprised predominantly of C18 stearyl and C22 behenyl groups. Previous studies examined combinations of BVE with Brassica Alcohol, a fatty alcohol with a similar C18-C22 alkyl chain length distribution. Although this combination provided satisfactory conditioning performance, it was unable to deliver the same levels of wet and dry comb force reduction as BTAC. In the present study, we demonstrate that the LGN formed by combining BVE with cetearyl alcohol (a 50/50 mixture of C16 cetyl and C18 stearyl alcohols) can provide equivalent conditioning performance to BTAC/cetearyl alcohol systems. The results are explained in terms of LGN microstructure and their effects on macroscopic formulation properties.
Conclusions
This study demonstrates that proper formulation of LGN systems enables cationic amino lipid conditioning agents such as BVE to deliver equivalent conditioning performance to traditional quats, e.g. BTAC. By varying the C-chain length and use level of the fatty alcohol cosurfactant in the LGN system, conditioning intensity can be modulated to deliver conditioning benefits that are desirable for specific hair types, e.g. lighter conditioning for fine hair vs. heavier conditioning for dry, damaged, or chemically processed hair.
Cationic amino lipids have been established as a more sustainable alternative to traditional cationic surfactants due to their 100% renewable origin and superior human and environmental safety profiles. Unlike traditional quaternary ammonium cationic surfactants, i.e. “quats”, used in hair care, amino lipids
derive their cationic character from protonation of their primary amine moieties that are derived from natural amino acids. Like other long chain cationic surfactants, amino lipids such as Brassicyl Valinate Esylate (BVE) are typically formulated with long chain fatty alcohols to yield lamellar liquid crystalline (LC) systems that demonstrate significant viscosity and yield value. These LC systems can stabilize hydrophobic oil phases and exhibit strong substantivity to hair, making them highly effective as rinse-off and leave-on hair conditioning products. The present study will examine the effects of fatty alcohol selection and use level on lamellar gel network (LGN) formation and properties when formulating with BVE and provide a comparison to the industry benchmark for conditioning performance, Behentrimonium Chloride (BTAC), a long chain quat.
Methods
Cationic surfactants, including BVE and BTAC, are formulated with varying ratios of different fatty alcohols to determine the effects of C-chain length and blend ratio on the LC phase behavior, LGN properties, and hair conditioning performance. LC structure and morphology are characterized using polarized light microscopy (PLM), small-angle X-ray scattering (SAXS), and cryo scanning electron microscopy (CSEM), and rheological analysis is used to quantify macroscopic fluid properties. Hair conditioning performance is assessed on hair tresses in terms of comb force reduction (wet/dry) and resistance to breakage, and by consumer perception during home-use.
Results
BVE is an amino lipid with a heterogenous alkyl chain length distribution comprised predominantly of C18 stearyl and C22 behenyl groups. Previous studies examined combinations of BVE with Brassica Alcohol, a fatty alcohol with a similar C18-C22 alkyl chain length distribution. Although this combination provided satisfactory conditioning performance, it was unable to deliver the same levels of wet and dry comb force reduction as BTAC. In the present study, we demonstrate that the LGN formed by combining BVE with cetearyl alcohol (a 50/50 mixture of C16 cetyl and C18 stearyl alcohols) can provide equivalent conditioning performance to BTAC/cetearyl alcohol systems. The results are explained in terms of LGN microstructure and their effects on macroscopic formulation properties.
Conclusions
This study demonstrates that proper formulation of LGN systems enables cationic amino lipid conditioning agents such as BVE to deliver equivalent conditioning performance to traditional quats, e.g. BTAC. By varying the C-chain length and use level of the fatty alcohol cosurfactant in the LGN system, conditioning intensity can be modulated to deliver conditioning benefits that are desirable for specific hair types, e.g. lighter conditioning for fine hair vs. heavier conditioning for dry, damaged, or chemically processed hair.