Monomer blended electrochemical polymerization in chiral liquid crystals to produce electro-optically active copolymer

Abstract

Electro-optically active low-bandgap conjugated copolymers were obtained by electrochemical polymerization (EP) in cholesteric liquid crystal (CLC). We prepared CLC electrolyte mixture blends of monomers, and electrochemically polymerized for obtaining conjugated copolymer with optical activity, in which the structure of the CLC is transferred, from achiral monomers on a CLC template. In addition, this copolymer showed a narrow bandgap and a significant red shift of the absorption band compared to the homopolymer. The optical rotatory dispersion (ORD) indicates that the polymer is chiroptically active and that the optical rotation can be tuned via redox. The guest monomers used for the EP in liquid crystal (LC) require solubility in the host LC and a rod-like structure, limiting their structural design. This technique has the advantage that complex synthesis of monomers is no required, and simple composition of monomers can be used to prepare copolymer films in a convenient manner by blending various monomers. This method expands the design range of optically active electrochromic devices based on conjugated polymers with pleochroic properties.

Graphical Abstract

Keywords:

• Monomer blend
• isothianaphthene
• chirality transfer
• liquid crystal

Acknowledgements

We would like to thank the OPEN FACILITY, Research Facility Center for Science and Technology, University of Tsukuba for using NMR and Glass Work Shop of University of Tsukuba.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Additional information

Funding

This research was supported by Japan Society for the Promotion of Science (JSPS), Grants–in–Aid for Scientific Research (No. 20K05626).