AN X-RAY PHOTOELECTRON SPECTROSCOPIC INVESTIGATION OF THE SELECTIVITY OF HYDROXYL DERIVATIZATION REACTIONS

The selectivity of trifluoroacetic anhydride (TFAA), used for the vapor-phase derivatization of hydroxyl groups in multifunctional oxygen-containing polymeric surfaces, has been investigated by XPS studies on model epoxide systems. The reactivity of TFAA towards epoxides observed here is discussed in the context of the large amount of published literature implying high selectivity of this reaction towards hydroxyl groups. Acetyl chloride (AcCl) and heptafluorobutyryl chloride (HFBuCl), used to derivatize hydroxyl groups in the literature, were also examined, with regard to cross-reaction with epoxides. Both AcCl and HFBuCl react with epoxides, forming chloroacetates and perfluorinated chloroacetates, respectively. Moreover, HFBuCl is shown to react with double bonds forming perfluorinated chloroacetates, while AcCl is unreactive towards them. The reactivity of HFBuCl towards epoxides and unsaturation compromises its use as a derivatization reagent for hydroxyl groups. However, the unique reaction products formed by exposure of hydroxyls and epoxides to AcCl vapor may allow hydroxyl species to be distinguished from epoxides in multifunctional carbon-oxygen polymeric surfaces.