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:The interfacial region of a model, multilayer coating system on an aluminium substrate has been investigated by high resolution time-of-flight secondary ion mass spectrometry (ToF-SIMS). Employing ultra-low-angle microtomy (ULAM), the interface between a poly(vinylidene difluoride) (PVdF) based topcoat and a poly(urethane) (PU) based primer 'buried' over 20µm below the PVdF topcoat's air/coating surface was exposed. Imaging ToF-SIMS and subsequent post-processing extraction of mass spectra of the ULAM exposed interface region and the PVdF topcoat and PU primer bulks indicates that the material composition of the polymerpolymer interface region is substantially different to that of the bulk PVdF and PU coatings. Analysis of the negative ion mass spectra obtained from the PVdF/PU interface reveals the presence of a methacrylate based component or additive at the interface region. Reviewing the topcoat and primer coating formulations reveals the PVdF topcoat formulation contains methyl methacrylate (MMA)/ethyl acrylate (EA) acrylic co-polymer components. Negative ion ToF-SIMS analysis of an acrylic copolymer confirms it is these components that are observed at the PVdF/PU interface.Post-processing extraction of ToF-SIMS images based on the major ions of the 2 MMA/EA co-polymers reveals these components are observed in high concentration at the extremities of the PVdF coating i.e. at the polymer-polymer interface but are also observed to be distributed evenly throughout the bulk of the PVdF topcoat. These findings confirms that a fraction of the MMA/EA acrylic co-polymers in the formulation segregate to the topcoat-primer interface where they enhance the adhesive properties exhibited by the PVdF topcoat towards the underlying PU primer substrate.

Thermally initiated reactions that occur between a polyester resin and a hexamethoxymethyl melamine crosslinker, together with the segregation phenomenon of minor components such as flow agents, have been investigated by high-resolution XPS. High-resolution monochromated XPS C 1s spectra can be peak-fitted by taking into account all functionalities of the respective components of the formulation. Uncured and cured coatings based on a mixture of hexamethoxymethyl melamine and a polyester resin exhibit minor differences in terms of surface composition and in the high-resolution C 1s peak fitting. Examination of both the elemental and chemical surface compositions clearly demonstrates that the use of flow agents in the formulation leads to their preferential segregation towards the air/film interface.