Anisotropic films photopolymerized from aligned cross‐linkable gemini ammonium liquid crystals for ion conduction

• Published in: Journal of applied polymer science Vol. 136; no. 15
• Main Authors: Wang, Caihong, Cao, Siyu, Li, Peiqi, Tan, Shuai, Wu, Yong
• Format: Journal Article
• Language: English
• Published: Hoboken, USA John Wiley & Sons, Inc 15.04.2019; Wiley Subscription Services, Inc
• Subjects: Anisotropy; Electrochemical impedance spectroscopy; gemini ionic monomers; ion conduction; Ion currents; Ionic liquids; Ions; Liquid crystals; Materials science; Molten salt electrolytes; Photopolymerization; Polymers; Small angle X ray scattering; Solid electrolytes
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.47349

ABSTRACT Cross‐linkable gemini ionic liquid crystals are prepared by jacketing the diammonium moiety between two biphenyl benzoate mesogens. Anisotropic films are obtained by photopolymerization of the macroscopically aligned gemini ionic liquid crystals for ion conduction. Small angle X‐ray scattering (SAXS) measurements indicate that the monolayer nanostructure is formed in the films and scanning electron microscope (SEM) observations reveal that the smectic layers are perpendicular to the film surface. Electrochemical impedance spectroscopy (EIS) characterization shows that the films exhibit strong anisotropy in ion conduction. The ion conduction across the film is enhanced while that within the plane of the film is impeded. The ionic conductivity in vertical direction of the film reaches up to 10−3 cm S−1 at 180 °C and the measured anisotropy (ratio of the measured conductivities in vertical direction of the film versus in parallel to the film) is 100–350. The photopolymerization of the cross‐linkable gemini ammonium liquid crystals offers excellent potential for the development of solid electrolytes for electrochemical devices. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47349.