Equilibration Reaction of Silicone Fluids

January 4, 2006 | Contact Author | By: Anthony J. O'Lenick, Jr., Siltech LLC; Kirk N. Wiegel, Department of Chemistry, University of Wisconsin; and Thomas G. O’Lenick, Department of Chemistry, Georgia Southern University
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Keywords: polymers | silicone fluids | synthesis | equilibration reaction | polydimethyl siloxane | cyclomethicone | viscosity

Abstract: Silicone compounds resemble organic compounds in their ability to make derivatives, but they are fundamentally different because they are equilibrium products. The nature of the equilibrium and the composition of the equilibrium mixture are the key factors. This is important because cyclic compounds are undesirable in personal care products.

Silicone fluids are used in many cosmetics and personal care products. This article looks at the synthesis of silicone fluids and evaluates whether that process can be viewed as an equilibrium reaction.

Silicone fluids are a class of compounds that have become known by a variety of names including silicone oils, dimethyl fluids, dimethyl polysiloxane, and polydimethyl siloxane. Silicone fluids have become an important class of materials over the years. These materials are unique in terms of chemistry when compared to hydrocarbon-based materials. While much has been learned about these compounds since they were developed in the 1940s, the available published data remains somewhat limited related to certain aspects of the chemistry. Silicone fluids are sold by their viscosity. Commercial products range in viscosity from 50 centistokes (cst) to 1,000,000 cst. Silicone fluids are divided into several classes based upon viscosity. The first is regular viscosity fluids (RVF) that include viscosities ranging from 50 cst to 1,000 cst. The second is the high viscosity fluids (HVF), that include viscosities ranging from 10,000 cst to 60,000 cst and the third is the ultra high viscosity f luids (UHF) which exceed 60,000 cst. If the product is not made by blending two different viscosity fluids, the viscosity is related to molecular weight. Silicone fluids conform to the structure shown in Figure 1. The viscosity allows for an approximate calculation of the value of “n” as shown in Table 1.

Silicone polymers have become an increasingly important component of personal care products. Table 2 lists some of the functions and use levels of silicone fluids in personal care products.