The chemical degradation of perfluorosulfonic acid (PFSA) membranes was studied both in‐situ (during fuel cell operation) and ex‐situ (by Fenton's test). During fuel cell operation, the degradation rate was quantified by monitoring the rate of fluoride release. The rate of degradation was found to be strongly dependent on operating conditions. Nuclear magnetic resonance (NMR) and mass spectrometry (MS) were used to identify degradation products other than fluoride generated during fuel cell operation. Strong similarities were found between the organic fragments generated from both the in‐situ (fuel cell operation) and ex‐situ (Fenton's test) degradation processes. The chemical structure of the fragment is consistent with that of the side chain on the PFSA ionomer used in the experiments. The implications of the existence of this product for the chemical degradation mechanism are discussed.

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The way in which chemically modified polymer surfaces (substrates) affect the activity of electroless catalysts was examined. Surfaces of three injection-molded styrene containing polymers [polystyrene (PS), poly(styrene-acrylonitrile) (SAN), and poly(acrylonitrile-butadiene-styrene) (ABS)] were modified by either plasma oxidation or by plasma oxidation followed by immersion in sodium hydroxide solution. After modification, two palladium catalyst systems (a two-step palladium catalyst and a commercial colloid catalyst) and six electroless baths were tested for activity in combinations with these surfaces. The activities ofthe two catalysts vary unpredictably and differently as the polymer, surface treatment, and electroless bath are changed. X-ray photoelectron spectroscopy results show only a weak correlation between surface composition and platability: (i) plasma-treated polymers show a net increase in surface oxygen, present mostly as carbonyl, (ii) immersing the plasma-exposed surfaces in alkaline solutions lowers oxygen and carbonyl concentrations. Some of these results differ from those previously obtained with photo-oxidized surfaces.

The surfaces of poly(styrene) (PS) and two polymers containing styrene, poly(styrene‐acrylonitrile) (SAN), and poly (acrylonitrile‐butadiene‐styrene) (ABS) were photo‐oxidized with 254 nm light and then treated with Pd‐ or Ag‐based electroless catalysts. These photo‐oxidized surfaces poisoned the Pd catalysts, hence inhibiting electroless metal plating, but the Ag‐based catalyst resisted deactivation by the modified surface. Results from x‐ray photoelectron spectroscopy (XPS) indicate that catalyst poisoning is due to photochemically produced carbonyl groups on the polymer surfaces, but show no spectroscopically significant change in the electroless catalysts. Treating irradiated polymers with alkaline solution restores platability and correlates with a loss of surface carbonyl groups by way of an alkaline decarbonylation reaction. Six electroless baths (two Cu and four Ni) were examined; the catalyst deactivation effect is independent of bath chemistry.

Recent mathematical approximations of &pz), the depth distribution of electron-excited x-rays, have opened up the possibility of accurate quantitative analysis of thin-film specimens by electron beam techniques. This method has been used extensively in electron probe microanalysis. This paper demonstrates quantitative analyses of thin films wing energydispersive x-ray analysis (EDS) coupled with the #(pz) methid. Metal and oxide films were analyzed by several techniques, including electron probe microanalysis (EPMA), Rutherford backscattering spectroscopy (RBS), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), spectroscopic ellipsometry (SE) and x-ray fluorescence spectroscopy (XRF); the results were compared with those obtained from the EDS thin-film analysis. In the case of A120, films, EDS film tbickness results agree to within +4%, +7% and f9% of the TEM, EPMA and SE results, respectively. For metal films, the EDS results agree to within f 12% (thicknesses) and f 7% (composition) of the RBS, EPMA and XRF results..