Formation of Layered Liquid Crystal by Cooperation of Sidechain Array and Rigid Polyacetylene Mainchain

ABSTRACT

An acetylene derivative monomer with a pyrimidine – type sidechain with three rings was synthesized by Steglich esterification. Polymerization of the acetylene derivative was then carried out with a rhodium complex. The acetylene monomer and mono-substituted polyacetylene derivative showed liquid crystals (LCs) because their tricyclic parts worked as a mesogenic core. The monomer as an acetylene derivative showed smectic with a tilted structure in the LC aggregation form. The mono-substituted polyacetylene bearing mesogen via short alkyl spacer showed lyotropic and thermotropic LCs of the smectic phase, although generally flexible long alkyl spacer from the main chain connected to sidechain mesogen is required for exhibiting liquid crystal in sidechain type polymer liquid crystals. In the present study, rigid mainchain aligns the sidechain mesogen array to form non-tilted LC. Properties of LCs were evaluated by various analytical techniques, including polarizing optical microscopy. Structural properties were evaluated by nuclear magnetic resonance spectroscopy, gel permeation chromatography, infrared spectroscopy, and ultraviolet – visible absorption spectroscopy.

Graphical Abstract

KEYWORDS:

• Conjugated polymer
• polarizing optical microscopy
• polyacetylene
• smectic liquid crystal

Acknowledgments

We thank the Glass Workshop, and Research Facility Center for Science and Technology, University of Tsukuba, for NMR measurements. Further, we would like to thank Midori Chemical (Midori Kagaku Co. Ltd.) for kindly gift 4-(2-(4-(dodecyloxy)-2-fluorophenyl)pyrimidin-5-yl)phenol to us.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary data

Supplemental data for this article can be accessed online at https://doi.org/10.1080/25740881.2024.2380864

Additional information

Funding

This research was supported by Japan Society for the Promotion of Science (JSPS), Grants-in-Aid for Scientific Research [No. 20K05626]. This work was supported by JST, the establishment of university fellowships towards the creation of science technology innovation, Grant Number [JPMJFS2106].

Notes on contributors

Kyoka Komaba

Dr. Kyoka Komaba was D3 student in University of Tsukuba, Goto laboratory.

Ryo Miyashita

Ryo Miyashita is currently PhD student in the Goto group.

Hiromasa Goto

Hiromasa Goto received his Ph.D. degree with a focus on liquid crystalline conjugated polymers from the University of Tsukuba under the supervision of Prof. Hideki Shirakawa (2000 Nobel Prize Laureate). H. Goto continues research on polymer liquid crystals and synthetic metals in the historic former Shirakawa laboratory. He developed electrochemical and chemical polymerization in liquid crystal and crystal. He likes to perform educational experiments with scientific demonstration for children.