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Surfaces of two widely used biomaterials -poly(tetrafluoroethylene) (PTFE) and poly(ethylene terephthalate) (PET) -have been modified using gas plasmas. The concentrations of hydroxyl, carboxyl, carbonyl and amine groups were analysed with chemical derivatization (CD), using different aldehyde, acetic anhydride, alcohol and hydrazine reagents, and SIMS. Quantification was done by comparing the CD/SIMS results with XPS atomic ratios. Ammonia helical resonator plasma (HRP) treatment was found to incorporate mainly amine and hydroxyl groups on both materials. Argon HRP treatment of PTFE and nitrogen capacitor plate plasma (CPP) treatment of PET were found to increase carboxylic functionalities. The double-bonded oxygen of the ester group of the unmodified PET was attacked and transformed to other groups in the order ammonia plasma > nitrogen HRP > nitrogen CPP, with carbonyl content being reduced to 2.6, 4.1, and 7.6 respectively from 13.5 groups per 100 carbon atoms of the untreated PET. Chemical derivatization greatly helped to distinguish between the functional groups on the plasma-treated surfaces. The difference between the surface specificity of SIMS and XPS has been discussed in the light of these results.

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