Lithium ion conductivity of polymers containing N-phenyl-2,6-dimethoxybenzamide framework in their side chains: Possible role of bond rotation in polymer side chain substituents for efficient ion transport

A new carbon-carbon main chain polymer with N-phenyl-2,6-dimethoxybenzamide on its each main chain carbon atom is prepared by Pd-initiated polymerization of diazoacetate containing the benzamide group, and the Li ion conductivity of the polymer doped with lithium bis(trifluoromethylsulfonyl)imide is evaluated along with its vinyl polymer counterparts with the same benzamide substituent. Although the expected high ion conductivity at low temperatures derived from a unique ion transport mechanism based on the bond rotation in the benzamide moiety reported in a literature is not observed, it is revealed that the dense packing of the benzamide group along the polymer main chain results in the enhanced ion conductivity. In addition, investigation of the correlation between ion conductivity and glass transition temperature of these solid polymer electrolytes (SPEs) reveals that other ion transport mechanism would operate in the benzamide containing SPEs than that derived from segmental motion of polymer chains observed in PEO-based SPEs.