Ion Transport in Supramolecular Ionic Liquid Crystals from Imidazolium Iodides and Hyperbranched Polyesters

Abstract

Polymeric liquid crystals (LCs) are attractive platforms for electrolyte design because their self-assembled nanostructures can generate organized ion-transport pathways while preserving the processability, thermal stability, and structural integrity required for next-generation electrochemical energy-conversion and storage devices. Herein, we report a synthetically simple and modular supramolecular strategy to transform commercially available hyperbranched bis-MPA polyester-64-OH (HBG4) into nanostructured ionic LC electrolytes by combining it with imidazolium iodide ionic liquids (ILs) bearing butyl, dodecyl, or perfluorinated chains. Hydrogen-bonding interactions between the terminal hydroxyl groups of the dendritic periphery and the imidazolium cations generate supramolecular ionic dendrimers in which distinct polar, dendritic, and apolar domains coexist within a single homogeneous polymeric material. In the bulk, cooperative nanosegregation of these domains drives self-assembly into robust smectic A LC phases over a broad compositional range, with mesophase stability strongly governed by the molecular architecture of the IL. Ionic conductivity measurements reveal clear composition–nanostructure–transport relationships, with conductivity modulated by IL content, temperature, mesophase stability, and the continuity of the polar ionic domains. In particular, perfluorinated ILs promote enhanced lamellar stability through fluorophilic segregation, whereas dodecyl-substituted ILs provide the best balance between high IL loading, LC order, and ionic transport. Overall, this work establishes hyperbranched polyesters as scalable supramolecular hosts for ILs and provides a practical route toward polymeric LC electrolytes with tunable nanostructure, ion-transport properties, and enhanced structural stability for electrochemical energy-conversion and storage applications.