Self-Assembly of Charged Diblock Copolymers with Reduced Backbone Polarity

Abstract

Charged block copolymers that can self-assemble into a host of nanostructures offer a great opportunity as nextgeneration battery electrolytes with outstanding ionic conductivity and mechanical robustness. The impact of ions on the selfassembly of charged block copolymers, however, remains to be fully understood. In this article, we report the phase behavior of charged-neutral block copolymers where a relatively nonpolar matrix was employed in the charged block to boost the strength of electrostatic interaction. The phase behavior was established using small-angle X-ray scattering (SAXS). We found that the overall shape of the phase boundary between ordered and disordered states is asymmetric, tilting toward the charged block-lean side of the phase portrait. However, the composition windows of the ordered phases, such as lamellae and hexagonally packed cylinders observed in this study, are comparable to those of neutral diblock copolymers and are not obviously affected by the incorporation of charges. The results obtained in this work provide insight into the impact of ions on the self-assembly of charged block copolymers as well as the design of nanostructured polymer electrolytes.

Recent advances in battery characterization using in situ XAFS, SAXS, XRD, and their combining techniques: From single scale to multiscale structure detection

“…In addition, due to safety concerns with organic electrolytes in LIBs, polymer electrolytes based on block copolymers (BCP) have received a lot of attention. [ 107–110 ] The SAXS results show diffraction peaks with a scattering vector ratio of 1:2:3 for the PNbFp 30 ‐ b ‐PNbPEO 27 /LiTFSI/IL complexes at ambient temperature (Figure 5D), indicating lamellar (LAM) nanostructures. The diffraction peaks with a scattering vector ratio of 1:$$\sqrt 3 $$:$$\sqrt 7 $$ confirm the transition of the nanostructures of the PNbFp 30 ‐ b ‐PNbPEO 32 /LiTFSI/IL complexes from an LAM phase to a hexagonally packed cylindrical (HEX) phases when the content of the short poly(ethylene oxide) (PEO) in the BCP increases (Figure 5E).…”