Liquid crystal photo-cross-linking phenomenon: synthesis of disubstituted polyacetylenes and emission from liquid crystal

Two types of disubstituted polyacetylenes were synthesized and these polyacetylenes exhibited both liquid crystallinity and luminescence. First, a simple disubstituted polyacetylene with short alkyl chains was synthesized by one-step reaction. The disubstituted polyacetylene derivative showed high molecular weight and high crystallinity. Next, a disubstituted polyacetylene derivative having long alkyl chains with photo-cross-linking of liquid crystal domains under visible light was prepared via multi-step reaction. Both the polymers showed good solubility. The polymers exhibited lyotropic liquid crystallinity, a smectic phase, and liquid crystal concentration chromism as a function of color change depends on concentration in solution. The polymers were oriented under a magnetic field. Characterization of the disubstituted polyacetylenes was carried out with nuclear magnetic resonance spectroscopy, gel permeation chromatography, infrared spectroscopy, UV-vis absorption spectroscopy, fluorescence spectroscopy, and polarizing optical microscopy observations. Magnetic orientation in evaporation process via formation of lyotropic liquid crystal for obtaining uniaxial domain structure was performed.

Automated summary

Two types of disubstituted polyacetylenes were synthesized, one with short alkyl chains and another with long alkyl chains that underwent photo-cross-linking to form liquid crystal domains. Both polymers showed good solubility and exhibited liquid crystalline and luminescent properties.