Low Dose Mapping of Semicrystallinity in Polymer Membranes with cryogenic 4D-STEM

Abstract

The understanding of the internal organization of soft materials such as polymer membranes is crucial in the development of new energy materials such as fuel cell membranes. TEM studies have played a major role in the characterization of the microphase separated domains of these materials and demonstrate their effects on their conductivities and mechanical properties [1,2]. The role of crystalline domains in these systems on ion conductivity, water uptake and durability presents another area of current interest [3]. Previous work has demonstrated the use of cryogenic scanning nanobeam electron diffraction (cryo-NBED) to visualize crystallinity in soft materials including polymer thin films with a resolution down to 10 nm [4]. Here, we show that reducing the dose by a factor of 10 enables imaging of small crystalline domains, just a few nanometers in size, within semicrystalline polymer membranes.