TOF-SIMS AND XPS ANALYSIS OF THE SURFACE CHEMICAL-STRUCTURE OF SOME LINEAR POLY(ORTHOESTERS)

The surface chemical composition of a range of poly(orthoester) copolymers has been examined by using time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). A good correlation was observed between the theoretical and experimental elemental and chemical state data obtained by XPS. The ToF-SIMS spectra revealed a consistent fragmentation pattern throughout the copolymer series where ions detected were diagnostic of each repeat unit including high molecular weights diads and triads arising from the poly(orthoester) copolymer sequence. The intensity of the ions specific to the diols was shown to reflect the bulk composition in a quantitative manner. The nature of the fragmentation was interpreted in terms of cleavage of the ether bonds linking the diol and orthoester unit and through the endocyclic and exocyclic cleavage of the orthoester bonds.