Cryogenic 4D-STEM analysis of an amorphous-crystalline polymer blend: Combined nanocrystalline and amorphous phase mapping
Jennifer Donohue,
Steven E. Zeltmann,
Karen C. Bustillo,
Benjamin Savitzky,
Mary Ann Jones,
Gregory F. Meyers,
Colin Ophus,
Andrew M. Minor
Affiliations
Jennifer Donohue
Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA 94720, USA
Steven E. Zeltmann
Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA 94720, USA
Karen C. Bustillo
National Center for Electron Microscopy, Molecular Foundry, LBNL, Berkeley, CA 94720, USA
Benjamin Savitzky
National Center for Electron Microscopy, Molecular Foundry, LBNL, Berkeley, CA 94720, USA
Mary Ann Jones
Core R&D - Analytical Sciences, The Dow Chemical Company, Midland, MI 48667, USA
Gregory F. Meyers
Core R&D - Analytical Sciences, The Dow Chemical Company, Midland, MI 48667, USA
Colin Ophus
National Center for Electron Microscopy, Molecular Foundry, LBNL, Berkeley, CA 94720, USA
Andrew M. Minor
Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA 94720, USA; National Center for Electron Microscopy, Molecular Foundry, LBNL, Berkeley, CA 94720, USA; Corresponding author
Summary: Understanding and visualizing the heterogeneous structure of immiscible semicrystalline polymer systems is critical for optimizing their morphology and microstructure. We demonstrate a cryogenic 4D-STEM technique using a combination of amorphous radial profile mapping and correlative crystalline growth processing methods to map both the crystalline and amorphous phase distribution in an isotactic polypropylene (iPP)/ethylene-octene copolymer (EO) multilayer film with 5-nm step size. The resulting map shows a very sharp interface between the amorphous iPP and EO with no preferential crystalline structure near or at the interface, reinforcing the expected incompatibility and immiscibility of iPP and EO, which is a short-chain branched polyethylene. This technique provides a method for direct observation of interfacial structure in an unstained semicrystalline complex multicomponent system with a single cryogenic 4D-STEM dataset.
