We report a systematic FTIR study of the perturbation of water “sorbed” into the polymers PET and PVC as a function of crystallinity (PET) or plasticizer content (PVC). Band shapes of the composite ν(OH) band of H2O obtained by the ATR technique have been fitted to individual components,corresponding to those recently found for pure water itself. A detailed quantitative analysis of the frequency shifts and relative intensties has led to conclusion that these component bands show direct evidence for the breaking of the water network in the polymer matrix and that this process depends on the polymer chemical and/or physical properties. Evidence is also found for interactions of water with the polymer at the lower end of the hydrogen bond interaction scale. The component band relative intensities (compared with those of pure water) have been used to compute an intensity enhancement parameter, P, which is a measure of the perturbation of a particular water distribution due to dissolution in the polymer matrix. For PET, P varies systematically with density, reflecting the ability of water to penetrate the polymer microstructure. For PVC the plasticizer content (and hence T g) has a considerable influence on the sorption (and swelling) process and on the equilibrium content and state of water. Thus, ATR-FTIR has been used for the first time to demonstrate,via intensity enhancement, the extent of electronic perturbation at a polymer/water interface.

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The recent development of Raman microscopes with high optical throughput and very sensitive CCD cameras has led to Raman spectroscopy again competing effectively with FTIR methods for materials analysis. Modem Raman instruments, designed to operate confocally without serious alignment or energy trade-off problems, allow depth profiling of optically transparent polymers and polymer matrices to be routinely 4The range of possible applications is increasing rapidly. It is clear that Raman microscopy will become a very important tool for future materials analysis, both in the polymer area and many other areas.

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Raman microscopy is rapidly becoming the technique of choice for the analysis of polymer surfaces and interfaces. The short (visible or UV) source wavelength, combined with high throughput spectrometers [1,2] and very sensitive (CCD) two dimensional detectors provide an analytical tool with molecular discrimination and micron scale mapping capability. The confocal capability of modern Raman microscopes (CRM) gives additional depth-profiling information [2,3,] (without sectioning) for materials "transparent" to the source laser. There are now a wide range of potential applications of such a system and therefore an increasing range of commercial instruments on the market [4]. We outline here just three examples of how this technique can be employed to enhance the quality of materials characterisation.Commercial PET "film" (such as that used for overhead projector slides and other products) is a co-extended biaxially oriented laminate comprising a layer of PET ( Fig. 1a and 1b) and PET containing an isophthalate comonomer to reduce crystallinity (Fig. 1c). Since the Raman bandwidth of the "ν(C = O)" mode of PET is sensitive to crystallinity [5,6] it is possible to quantify the crystallinity gradient as shown in figure 2a. Comparison of CRM data with the result obtained by microtoming (to provide "lateral" measurements across the interface) shows good agreement (Fig. 2b) and underpins the validity of the confocal approach within the limit of a 2 µm 3 spatial resolution.An important issue around the incorporation of fungicides into paints and other polymer-containing coatings and consumer products is the potential loss of "active" in the ambient environment [7,8]. Figure 3 shows how CRM may be employed to map and depth profile the fungicide (PA3) content of a plasticised PVC film using the ratio of band intensities shown in figure 3b. The leaching process (water at 25°C for several hours) clearly leads to a loss of fungicide both from the surface and from the bulk (Fig. 3c) of the film. Such a loss of toxic material to the ambient has potential environmental impact and is therefore of significant commercial importance.The distribution of silane primer (such as Y9669 -see figure 4) across a polymer/glass laminate (Fig. 4a) and, in particular, accumulation at the polymer/glass interface is thought [9,10] to be a controlling factor for the adhesion mechanism in such materials. The relative amount of silane at a given depth into the polymeric material may be assessed