Comparative study by XPS of nitrogen and oxygen implantation in different carbonaceous polymers using flowing nitrogen plasma

Six different carbonaceous polymers-polyethyene (PE), polypropylene (PP), p olystyrene (PS), polyoxymethylene (POM), polymethylmethacrylate (PMMA) and polyethylene terephthalate (PET)-are submitted to a flowing nitrogen post-d ischarge plasma under similar experimental conditions, The nitrogen and oxy gen implantations are measured by XPS after a short air exposure of the tre ated specimens. The reactivity of these different carbonaceous polymers is compared from the carbon density variation [Delta(C) = (X-C'-X-C)/X-C] with in the XPS analysed depth, where X-i' and X-i refer to the atomic percentag e of atom i in the treated and in the initial polymer, respectively. Five p olymers have a negative Delta(C) value according to the order Delta(C) (PET ) < Delta(C PP) approximate to Delta(C PE) approximate to Delta(C) (PS) < D elta(C PMMA), implying that nitrogen and oxygen incorporation increases. On the contrary, POM has a positive Be value. The comparison between PE, PP a nd PS shows that substituting hydrogen in PE by a methyl (to give PP) or a phenyl (to give PS) group does not create any large differences in terms of reactivity, The major nitrogenated group is terminal imine, Substituting h ydrogen by an ester group (to give PMMA) decreases the polymer reactivity a nd the ester group remains unchanged. Imine is once again the major nitroge n-containing function. The comparison between PE and POM shows that the pol ymer chain structure has a considerable influence on the reactivity; PET ap pears to be the polymer that is able to incorporate the maximum nitrogen fu nctions, distributed between amine and imine terminal groups. Copyright (C) 2000 John Wiley & Sons, Ltd.