Determination of the Sorption Capacity and Swelling of Poly(n-Decyl Methyl Siloxane) in the Atmosphere of Hydrocarbons by the Ellipsometry Method

The spectroscopic ellipsometry method was used for the first time for investigating the thin layers (l < 300 nm) of the poly(n-decyl methyl siloxane) in the atmosphere of the gaseous n-alkanes CH₄, C₂H₆, and C₄H₁₀. The ellipsometric measurements have shown that the thickness of a layer of this polymer and the index of refraction of light by it change in the atmosphere of hydrocarbons. Data on the change in the thickness of a poly(n-decyl methyl siloxane) layer made it possible to calculate the isotherms of its swelling and of the sorption of hydrocarbons in it as well as the Flory–Huggins interaction parameter of this polymer. By the change in the index of refraction of light by specimens of the indicated polymer, the densities of the hydrocarbons C₂H₆ and C₄H₁₀, sorbed in it, and the coefficients of their solubility in this polymer at p → 0 were estimated.