Comparative Studies of Deposition and Formation of Complex Coacervates in Conditioning Shampoos
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Presented by: Giselle Cararo
INTRODUCTION: Hair is a diverse substrate, with different shapes, colors, and textures. Its properties vary in many ways and new hair care products are increasingly sought after. The change in appearance, shape, hair color, so common nowadays, causes damage that needs to be mitigated and repaired. In this regard, cationic polymers are widely used as conditioning and damage repair agents for hair. Polyquaternium-10 and Quaternized Guar Gum are two highly used components in the conditioning product development market. In shampoo and liquid soap formulations, the cationic polymer and the surfactant exist together in a single phase. With the dilution of the formulation during washing and rinsing, that is, at low concentrations of surfactants, the cationic polymers become poorly soluble in the medium, generating a liquid-liquid phase separation due to the formation of a gel-polycation-surfactant complex, or coacervate. During the coacervation process, the polymer and surfactant undergo a series of association and microstructure changes: from a condensed network to globular aggregation (coacervation) to interconnection and association with micelles. The coacervate is then a phase that contains a high level of cationic charge and its main function is to deposit the polymer on negatively charged substrates, forming a film. In addition, coacervates help in the deposition of insoluble actives, such as silicones. Some very relevant and desirable characteristics for the hair, such as shine, softness, and combability, are directly related to the conditioning of the hair and, consequently, to the deposition of cationic polymers and/or silicones on the surface of the hair.
OBJECTIVE: This work aims to evaluate the performance of shampoos from Grupo Boticario regarding the formation of complex coacervates in different dilutions containing the quaternary components Quaternized Gum Guar and Polyquaternium-10, combined with Dimethiconol (and) TEA-Dodecylbenzenesulfonate. Instrumental techniques were used to determine hair deposition, coefficient of friction, and combing work compared to a control (no silicone) and placebo formulations (no silicone and cationic polymer).
MATERIALS AND METHODS: Shampoo formulations with and without conditioning polymers, associated with Dimethiconol (and) TEA-Dodecylbenzenesulfonate, were prepared and evaluated regarding their organoleptic characteristics (appearance, color, odor, viscosity, and pH, when applied).
Slightly bleached and flat Caucasian hair tresses were used in this study, which were pre-treated with a 9% solution of Sodium Lauryl Ether Sulfate. Tresses were then moisted and treated with shampoo, rinsed, and dried in a standardized way.
The coefficient of friction (COF) was determined in a Diastron MTT-175 with a UVWin Controller, coupled with a parallelogram. There is a direct correlation between smoothness and COF. Ease of combing was also determined in a Diastron MTT-175 and UvWin Controller by the analysis of the total work needed to pass a comb through a hair tress. Both parameters are strong indications of the level of conditioning from the polymers in the shampoo formulation.
For the dilution study, each shampoo sample was subjected to consecutive dilutions to evaluate the formation of co-phases/coacervates. Weighting was performed on a semi-analytical scale and homogenization was manual and visually analyzed. The deposition was determined qualitatively and quantitatively by Scanning Electron Microscopy (SEM) and Electron Dispersive Spectroscopy (EDS) in Phenom ProX.
RESULTS: It was observed a significant increase in silicone deposition when Dimethiconol (and) TEA-Dodecylbenzene Sulfonate is associated with both Quaternized Guar Gum and Polyquaternium-10, correlating with the identification of precipitates in the dilution experiments. As a result, dry combing work has significantly decreased when compared to the placebo and control shampoos. However, no significant differences were identified in the coefficient of friction.
CONCLUSIONS: The results obtained in this study show that the presence of cationic polymers alters the conditioning behavior of shampoos containing silicone. Dilution studies showed the formation of poorly soluble complexes in the medium, which are associated with the increase in the deposition of silicones on hair tresses, resulting in the improvement of conditioning performance such as ease of combing.
All shampoos containing cationic and silicone polymers demonstrate an improved deposition and a reduction in dry combing work, reinforcing the importance of choosing and associating ingredients that form complex coacervates to create minimalist and effective shampoos, leading to cost-effective products with superior performance to consumers.
OBJECTIVE: This work aims to evaluate the performance of shampoos from Grupo Boticario regarding the formation of complex coacervates in different dilutions containing the quaternary components Quaternized Gum Guar and Polyquaternium-10, combined with Dimethiconol (and) TEA-Dodecylbenzenesulfonate. Instrumental techniques were used to determine hair deposition, coefficient of friction, and combing work compared to a control (no silicone) and placebo formulations (no silicone and cationic polymer).
MATERIALS AND METHODS: Shampoo formulations with and without conditioning polymers, associated with Dimethiconol (and) TEA-Dodecylbenzenesulfonate, were prepared and evaluated regarding their organoleptic characteristics (appearance, color, odor, viscosity, and pH, when applied).
Slightly bleached and flat Caucasian hair tresses were used in this study, which were pre-treated with a 9% solution of Sodium Lauryl Ether Sulfate. Tresses were then moisted and treated with shampoo, rinsed, and dried in a standardized way.
The coefficient of friction (COF) was determined in a Diastron MTT-175 with a UVWin Controller, coupled with a parallelogram. There is a direct correlation between smoothness and COF. Ease of combing was also determined in a Diastron MTT-175 and UvWin Controller by the analysis of the total work needed to pass a comb through a hair tress. Both parameters are strong indications of the level of conditioning from the polymers in the shampoo formulation.
For the dilution study, each shampoo sample was subjected to consecutive dilutions to evaluate the formation of co-phases/coacervates. Weighting was performed on a semi-analytical scale and homogenization was manual and visually analyzed. The deposition was determined qualitatively and quantitatively by Scanning Electron Microscopy (SEM) and Electron Dispersive Spectroscopy (EDS) in Phenom ProX.
RESULTS: It was observed a significant increase in silicone deposition when Dimethiconol (and) TEA-Dodecylbenzene Sulfonate is associated with both Quaternized Guar Gum and Polyquaternium-10, correlating with the identification of precipitates in the dilution experiments. As a result, dry combing work has significantly decreased when compared to the placebo and control shampoos. However, no significant differences were identified in the coefficient of friction.
CONCLUSIONS: The results obtained in this study show that the presence of cationic polymers alters the conditioning behavior of shampoos containing silicone. Dilution studies showed the formation of poorly soluble complexes in the medium, which are associated with the increase in the deposition of silicones on hair tresses, resulting in the improvement of conditioning performance such as ease of combing.
All shampoos containing cationic and silicone polymers demonstrate an improved deposition and a reduction in dry combing work, reinforcing the importance of choosing and associating ingredients that form complex coacervates to create minimalist and effective shampoos, leading to cost-effective products with superior performance to consumers.