Thermoplastic Silicone Elastomers Improve Nail Polish Performance

By: A. Schlosser and L. Hassenzahl, Wacker Chemical Corporation

Posted: July 25, 2005, from the July 2005 issue of Cosmetics & Toiletries.

Nail polishes are one of the traditional applications in color cosmetics and have been well developed over the years. Yet consumers are still looking for nail polishes with attributes such as more scratch resistance and less sensitivity to chipping. Such products would enable consumers to reduce the reapplication of nail polish by minimizing the damage occurring from daily life. We tested the ability of thermoplastic silicone elastomersa (TPSE) to improve the fi lm-forming and elastomeric properties of nail polish formulations.

Silicone polyurea copolymers are TPSEs.1 The basic technology behind these products is the copolymerization of α-ω aminosilicone fl uids with diisocyanates. 2-4 As shown in Figure 1, the resulting silicone polyurea copolymer has alternating silicone soft blocks and so-called organic hard blocks. The thermoplastic properties of TPSEs are based on intermolecular interactions. Hydrogen bridge bonds make them elastomers at low temperatures. An increase in temperature loosens these bonds, causing the products to soften and fi nally to become liquid. Lowering the temperature reverses this process and reverts the product back to its elastomeric state. The temperature at which softening begins can be adjusted by ratio and type of soft and hard blocks used in the reaction. This reversible property of TPSEs makes formulating easier.

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