HYDROGEN-BONDING .19. THE CHARACTERIZATION OF 2 POLY(METHYLPHENYLSILOXANE)S

Two commercial samples of poly(methylphenylsiloxane) were characterised using our solvation equation, log L = c + rR2 + s-pi(H)(2) + a-alpha(H)(2) + b-beta(H)(2) + l log L16 where L is the gas-liquid partition coefficient for a series of solutes on a given stationary phase, and the explanatory variables are R2 an excess molar refraction, pi(H)(2) the solute dipolarity/polarisability, alpha(H)(2) and beta(H)(2) the solute hydrogen-bond acidity and basicity, and log L16 where L16 is the solute gas-liquid partition coefficient on hexadecane at 25-degrees-C. For both samples, a substantial b-constant was found, viz. 1.22 +/- 0.07 and 0.49 +/- 0.08 at 25-degrees-C, suggesting that they can act as hydrogen-bond acid (contrary to their chemical formulation). Examination of the bulk liquid stationary phases by IR showed the presence of OH groups and confirmed our analysis by the solvation equation. It is suggested that workers using the OV or SE series of siloxanes routinely check the bulk stationary phases by IR in order to assess the presence or absence of OH groups.