A ToF‐SIMS investigation of a buried polymer/polymer interface exposed by ultra‐low‐angle microtomy

Abstract

: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.

ToF‐SIMS depth profiling of a complex polymeric coating employing a C60 sputter source

“…These peaks are attributed to the fragmentation of the PMMA/ poly(ethyl acrylate) (EA) based co-polymers included in the PVdF topcoat formulation (28) . It is interesting to note that these ions are the same as those observed by Hinder et al when investigating the segregation of acrylic copolymers to the PVdF topcoat/PU primer interface (23) . In Figure 4b It is observed in the inset in Figure 4a that the peak at higher mass, CH 3 O -, is the more intense of the two peaks, while in the inset in Figure 4b this fragment is the lower intensity peak.…”

“…Additionally, it is accepted within the coatings industry that the inclusion of acrylic copolymers as flow agents in the formulations contributes towards the adhesive properties exhibited by the PVdF topcoat towards primer coatings by improving substrate wetting. This is achieved by them segregating to the primer/topcoat interface as shown in a recent study, using ToF-SIMS, by Hinder et al (23) . The PVdF formulation used in these studies was pigmented with mainly blue and white pigments.…”

Examination of the interface of a model adhesive joint by surface analysis: a study by XPS and ToF‐SIMS

“…The sample was subsequently cured overnight at room temperature followed by two hours at 60°C. A histological microtome was used to cut the sample mounted with a taper using the ultra-low angle microtomy method as described by Hinder et al [1,2]. In this work an angle of 0.33 degrees was used.…”

An XPS and ToF-SIMS investigation of the outermost nanometres of a poly(vinylidene difluoride) coating

“…Hinder et al have investigated a variety of topics including intercoat adhesion between a PVdF topcoat and a poly(urethane) primer [10], the migration and segregation of a silicone additive through a PVdF topcoat [11] and the investigation of a PVdF topcoat/poly(urethane) primer interface buried 20 µm beneath a PVdF topcoats air/coating surface [12].…”