New-Generation Silicones in Hair Care

For a long time, the use of polymers and especially silicones in personal care formulations and the cosmetics sector has been expanding. Beginning in the early 1950s, silicone use in formulations was for protection and antifoaming purposes, but in subsequent years this application expanded significantly. In the 2000s, silicones were used for conditioning effects, color depth and protection, prevention of saponification, shine, protection, spreadability and many other properties. The development of new applications continued with technological advances in silicone polymer. The term silicone is used in literature in a general sense and refers to synthetic materials with polymeric, siloxane structure. The polydimethylsiloxane structure is shown in Figure 1.   The main chain of the polymer consists of silicon and oxygen atoms. Methyl groups are bonded to the Si-O chain. The Si-O bond is thermodynamically quite favorable. Additionally, methyl groups can rotate freely around the –Si-O-Si– chain. The possible modifications in PDMS structure are as extensive as those in carbon chemistry. This makes the technological evolution of the polymer inevitable. PDMS, thanks to such properties inherent in its structure, is highly useful not only in the personal care industry but also in sectors such as textiles, food, pharmaceuticals, agriculture, construction and building chemicals.

One of the most common variations of PDMS is amodimethicone (amino functional dimethicone).

Amino functional dimethicones further evolve to alkyl amodimethicone through modification where methyl groups in the main chain are replaced with alkyl amine groups (–R-NH2). Besides this modification, silicone copolymers composed of two or more different monomers have been developed, and this advancement has enabled variety and efficiency in formulations. The existence of many different hair types (fine, curly or treated) creates a need for specially developed hair care products for these hair types. For example, consumers with fine hair prefer volumizing products, while those with curly hair prefer anti-frizz or curl-defining products. Furthermore, the widespread use of hair dyes, chemical treatments and thermal straightening have revealed the need for functional properties such as protection and restoration for treated hair. New generation silicones with [AB]n copolymer technology help in the development of specialty products of high quality that meet consumer needs. Momentive Performance Materials, which first implemented this technology, introduced [AB]n silicone copolymers to consumers through its Silsoft product series. New generation [AB]n copolymers differ from amodimethicones in terms of hair substantivity. Chemical differences between newer technologies such as amodimethicones and [AB]n copolymers show significant differences in their substantivity to hair. The combination of [AB]n technology with additional reactive groups provides durability and resilience to hair, which offers potential restoration possibilities on damaged hair surfaces.

The main differences between traditional silicone oils and new generation polymers are as follows;

• The presence of additional reactive units in [AB]n copolymer structure provides durability and hair restoration potential. By applying reactive [AB]n copolymer as a conditioner to damaged and lightened hair, the hair's original hydrophobic state is restored. • Another problem in damaged hair is the tendency to frizz. Use of [AB]n copolymers as a conditioner reduced frizz by 30 percent after 10 washes with surfactant solution. • [AB]n copolymers, whether with or without reactive units, provide more efficient substantivity to hair compared to dimethicone and amodimethicone with simpler chemical structures.     Emre Nakay Technical Sales Manager Latro Kimya Dış Ticaret Ltd. Şti.    

References H. Lange, R. Wagner, A. Witossek, K-H Satachulla, S. Teuber, M. Kropfgans, K-H. Sockel, A. Möller, US 7,217,777, May 15, 2007; H. Lange, R. Wagner, M. Kropfgans, S. Musiol; WO2004/069137, 2004. M. Kropfgans, and J. Tully, Eurocosmetics, 10, October 2008, 18 – 23, printed. C.R. Robbins, Chemical and Physical behavior of Human hair, 4th Ed., Springer-Verlag, New York, 2002. A. Dussaud and L. Fieschi-Corso, Influence of Functionalized Silicones on Hair Fiber-Fiber Interactins and on the Relationship with the Macroscopic Behavior of Hair Assembly, J. Of Cosmetic Science, printed. Halloran, D. J., "A Silicone Selection Guide for Developing Conditioning Shampoos," Soap, Cosmetics, Chemical Specialties, 68:3, 22-26 (March 1992). Momentive Performance Materials, Silsoft CLX-E Marketing Bulsletin, 2015.