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Brush‐First ROMP of poly(ethylene oxide) macromonomers of varied length: impact of polymer architecture on thermal behavior and Li+ conductivity

Shibuya, Yoshiki, Tatara, Ryoichi, Jiang, Yivan, Shao‐Horn, Yang, Johnson, Jeremiah A.
Journal of polymer science 2019 v.57 no.3 pp. 448-455
electrolytes, lithium, molecular weight, polyethylene glycol, polymerization, thermal properties
The properties of polymeric materials are dictated not only by their composition but also by their molecular architecture. Here, by employing brush‐first ring‐opening metathesis polymerization (ROMP), norbornene‐terminated poly(ethylene oxide) (PEO) macromonomers (MM‐n, linear architecture), bottlebrush polymers (Brush‐n, comb architecture), and brush‐arm star polymers (BASP‐n, star architecture), where n indicates the average degree of polymerization (DP) of PEO, are synthesized. The impact of architecture on the thermal properties and Li⁺ conductivities for this series of PEO architectures is investigated. Notably, in polymers bearing PEO with the highest degree of polymerization, irrespective of differences in architecture and molecular weight (~100‐fold differences), electrolytes with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) as an Li⁺ source exhibit normalized ionic conductivities (σₙ) within only 4.9 times difference (σₙ = 29.8 × 10⁻⁵ S cm⁻¹ for MM‐45 and σₙ = 6.07 × 10⁻⁵ S cm⁻¹ for BASP‐45) at a concentration of Li⁺ r = [Li⁺]/[EO] = 1/12 at 50 °C. © 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 448–455