Determination of the bulk structure of technical multiphase polymer systems with AFM: comparative AFM and TEM investigation

Abstract

The state-of-the-art characterization technique for the bulk morphology of technical multiphase polymer systems is currently transmission electron microscopy (TEM). With the development of numerous dynamic measuring modes, atomic force microscopy (AFM) is now also capable of mapping multiphase polymer systems with extremely high resolution and material contrast. Nevertheless, the vast majority of the latter work has been conducted on thin-film model systems, in most cases cast or spin-coated from solution. For most industrial applications of polymer systems, however, the bulk morphology is of primary interest In the present paper, surface preparation techniques (microtoming, press moulding and partial dissolution) for AFM investigation of the bulk morphology of technical polymer systems are discussed and AFM results-in most cases tapping mode images with phase detection-are compared systematically with TEM data. Atomic force microscopy is not only capable of accessing simple phase distributions, as in the ABS blend, but it can also give insight into more complex inner particle structures as in certain types of ASA or PP blends. Compatibilizer distributions can be mapped too. In all these cases, TEM and AFM results are in line with each other, in some cases complimentary. Tapping mode phase-contrast mapping together with classical cryomicrotoming yielded the best results with most of the polymers in the study. Press moulding or partial dissolution, although simpler, yielded only partial information on the morphology of the systems.