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Simple and Sensorial: Amino-modified Silicone Protects and Revives Hair

Contact Author Nisaraporn Suthiwangcharoen, Ph.D., Bethany Prime, Beth Johnson and Dawn Carsten, Dow Consumer Solutions, Midland, Michigan, USA
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Read the full article in the February 2021 digital edition. . .

Achieving healthy-looking hair that feels moisturized and undamaged is what would be considered “a good hair day” by most consumers. And every hair type, whether dark or light-colored, fine or thick, curly or straight, needs care and protection from everyday grooming routines.

In an increasingly competitive market, not only are products with measurable performance sought, but also those that help to streamline consumers’ hair care routines by providing multiple benefits in one step; for example, restoring hair’s condition while offering moisturization and protection. As such, a multifunctional approach to hair conditioning could meet the consumer demand for simplicity while streamlining their hair care process. Presented here is one such technology—a terminal hydroxy amino-modified silicone (THA)a designed to address multiple hair care needs while also imparting a good sensory experience.

THA Chemistry

Conventionally, aminosiloxane polymers with the common INCI name of amodimethicone have widely been used in hair care. They provide a broad range of benefits, including a soft and silky feel, color and heat protection, and hair styling, high gloss and antistatic properties.1 They consist of two components: amino functionality and a non-functional polydimethylsiloxane (PDMS) chain.

Due to a strong polar interaction of the amine moieties with the negatively charged hair proteins,2 the amino functionality facilitates deposition onto hair while the silicone spreads over the hair surface and forms a thin, hydrophobic layer.2 This hydrophobic coating on the hair provides protection and alters the way the hair feels to the consumer.

The properties of aminosiloxane polymers are mainly controlled by the structure of the aminoalkyl groups, their concentration and position in the polymer chain, the charge density, and the molecular weight of the polymer. As such, it is critical to determine the amine level in aminosiloxanes and reach a fine balance between amine and silicone to achieve adequate deposition for optimal conditioning.

In addition to amine levels, the placement of the amine functional groups can impact overall conditioning performance. Previous findings suggest that the amine functionality as an endgroup to a polysiloxane chain significantly improves conditioning performance on hair, compared with grafted or pendant aminosiloxanes.3, 4 Also, by matching the interfacial tension of silicone to the hair’s surface energy, the terminal amino silicone can provide improved conditioning and increased deposition particularly onto colored and damaged hair.5, 6

Described herein, THA—specifically, bis-diisopropanolamino-PG-propyl disiloxane/bis-vinyl dimethicone copolymera—has terminal amino functional groups on a siloxane chain as well as hydroxy functionality to enhance its performance. Notably, the polymer is low in cyclic content and meets REACH requirements. In terms of performance, as will be shown, the siloxane chain imparts softness while the amines improve silicone deposition and the hydroxy groups provide a unique sensory experience; all in one step.

Materials and Methods

Various experiments were performed to measure the effects on friction, breakage, drying time, strand alignment, wet and dry combing, colorfastness and sensory characteristics of different aminosilicones in comparison with THA. Two formulas were prepared for testing: a rinse-off conditioner and leave-in conditioner (see Formulas 1 and 2, respectively).

Hair preparation: Slightly bleached Caucasian hairb was used to test the conditioners unless otherwise specified. Three tresses were used for each treatment. Each tress was washed with 9% SLS before each experiment, treated with rinse-off or leave-in conditioner, then air-dried at room temperature prior to analysis.

. . .Read more in the February 2021 digital edition. . .

References

  1. Lim, Y.H., Park, C.H. and Kim, J. (2010). Hair conditioning effect of amino silicone softeners in varied treatment conditions. Fibers and Polymers 11 507-515; doi:10.1007/s12221-010-0507-9
  2. Lubkowska, M. and Stanczyk, W. (2014). Aminoalkyl functionalized siloxanes. Polimery 59 763-768.
  3. Davies, A.G. and Shiel, S.W. (2002). Terminal aminofunctional polysiloxane hair conditioning compositions and their use in hair coloring compositions. US7211243B2.
  4. Wells, R.L. and Hughes, K.J. (2010). Conditioning shampoo containing aminosilicone. US20100061952A1.
  5. Gray, J. (2017). In Baran, R. and Maibach, H.I., eds, Textbook of Cosmetic Dermatology ch 27, pp 238-240. CRC Press: Boca Raton, FL.
  6. Marsh, J., Gray, J. and Tosti, A. (2015). In Healthy Hair, pp 108-111. Springer: New York.

Captions/Figures:

a HydroxySHIELD (INCI: Bis-Diisopropanolamino-PG-Propyl Disiloxane/Bis-Vinyl Dimethicone Copolymer) is a product of Dow Consumer Solutions.

b International Hair Importers and Products Inc.

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Formula 1. Rinse-off Test Conditioner

Rinse-off test conditioner formula.

Formula 2. Leave-in Conditioner Test Formula

Test formula for leave-in conditioner. 

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