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

doi:10.1016/j.isci.2022.103882

Cryogenic 4D-STEM analysis of an amorphous-crystalline polymer blend: Combined nanocrystalline and amorphous phase mapping

iScience. 2022 Feb 5;25(3):103882. doi: 10.1016/j.isci.2022.103882. eCollection 2022 Mar 18.

Authors

Jennifer Donohue¹, Steven E Zeltmann¹, Karen C Bustillo², Benjamin Savitzky², Mary Ann Jones³, Gregory F Meyers³, Colin Ophus², Andrew M Minor^{1

2}

Affiliations

¹ Department of Materials Science and Engineering, UC Berkeley, Berkeley, CA 94720, USA.
² National Center for Electron Microscopy, Molecular Foundry, LBNL, Berkeley, CA 94720, USA.
³ Core R&D - Analytical Sciences, The Dow Chemical Company, Midland, MI 48667, USA.

Abstract

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.

Keywords: Materials characterization; Materials science; Polymer chemistry.