VAPOR-PHASE CHEMICAL DERIVATIZATION FOR THE DETERMINATION OF SURFACE FUNCTIONAL-GROUPS BY X-RAY PHOTOELECTRON-SPECTROSCOPY

A vacuum adsorption apparatus has been used for vapour-phase chemical derivatisation of standard polymers, to identify specific reactions fo r carboxylic acid and carbonyl functional groups. The reactivity and s electivity of trifluoroethanol (TFE)-pyridine-di-tert-butylcarbodiimid e and 3-(trifluoromethyl)phenylhydrazine for these respective groups w ere studied. Depths of reaction were also investigated using F 1s/F 2s peak intensity ratios determined by X-ray photoelectron spectroscopy (XPS). The TFE-/pyridine-/di-tert-butylcarbodiimide system was found t o be suitable for the selective derivatisation of carboxylic acid grou ps, achieving ca. 75% conversion of carboxylic acid groups. The depths of fluorine incorporation for both the TFE and TFAA reactions were fo und to be invariant with reaction time over the XPS sampling depth for the range of conditions stud led. Derivatisation of carbonyl groups u sing 3-(trifluoromethyl)phenylhydrazine was not sufficiently selective , reactions being observed with hydroxy and carboxylic acid groups. Fl ame treatment of polyethylene produced oxidised surfaces with a Variet y of functional groups. Using the methods described above and previous ly reported the hydroxy and carboxylic acid group concentrations were found to be invariant with flame intensity, with the latter having the consistently lower concentration.