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Polynorbornene-Based Polyelectrolytes with Covalently Attached Metallacarboranes: Synthesis, Characterization, and Lithium-Ion Mobility

Publication at Faculty of Science |
2021

Abstract

Metallacarborane clusters, such as COSAN, belong to surface-active and low-coordinating nanosized anions. Therefore, they have been used as separate building blocks in self- and co-assembly.

As a step forward, we synthesized via ringopening metathesis polymerization a novel polyelectrolyte, poly(norbornene-COSAN), PNC, with metallacarborane anions covalently attached to a polynorbornene backbone. The resulting PNC, with the degree of polymerization around 120, is soluble in polar organic solvents, and it can be deposited on a substrate as separate polymer chains or as multichain aggregates, with the bundle-of-fibril patterning.

PNC is miscible with polyethylene oxide (PEO), forming the PNC/PEO composite. As shown by solidstate nuclear magnetic resonance spectroscopy, Li+ counterions are firmly coordinated in the PNC matrix, exhibiting rather restricted dynamics.

In contrast, the mixing of PNC with PEO leads to a substantial increase of Li+ dynamics. As the result, the mobility of Li+ in the PNC/PEO composite remains almost unrestrained, which makes the COSAN-containing polyelectrolytes promising candidates for ion-conducting materials.