| Co-Investigator(Kenkyū-buntansha) |
HIRAI Asako Institute for Chemical Research, KYOTO UNIVERSYTY, Instructor, 化学研究所, 助手 (20156623)
KAJI Hironori Institute for Chemical Research, KYOTO UNIVERSYTY, Instructor, 化学研究所, 助手 (30263148)
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| Research Abstract |
Hydrogen bonding and dynamic factor affecting structure formation process habe been investigated for main-chain thermotropic liquid crystalline polyurethane(LCPU) and polyether(LCPE) composed of the same biphenylene mesogen and methylene spacer units by DSC, polarizing light microscopy, solid-state ^<13>C and ^<15>N NMR spectroscopy, and wide-angle X-ray diffractometry. Detailed DSC mesurements reveal that there are great differences in liquid crystallization and crystallization processes between LCPU and LCPE probably due to the presence and absence of intermolecular NH - CO hydrogen bonding. In the super-cooled liquid crystalline component, which exists as the noncrystalline component in the samples crystallized form the melt, the spacer conformation and mesogen mobility are also found tobe markedly different between the two samples.These facts suggest the formation of some kind of molecular assemblies through intermolecular hydrogen bonding in the liquid crystalline state for LCPU.
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On the basis of detailed DSC analyses, it is found that liquid crystalline glass is formed for LCPE by quenching from the melt to ice-water. From this type of the liquid crystailline glass, form β is mainly crystallized by annealing at temperatures lower about 60℃ while form α is preferentially produced at higher temperatures. Moreober, form β with much higher crystallinity is crystallized when the stable nematic phase at 130℃ is rapidly quenched to ice-water. Here, such a stable nematic phase is produced by rapidly heating the liquid crystalline glass to 130℃ in a silicone oil bath and no apparent change in its structure seems to occur at least for two days. Detailed structural analyses of forms α and β as well as the stable nematic phase are in progress to obtain further information about the crystallization mechanism of the two forms in relation to the possible reorientation of molecular chains in the nematic phase. Through these investigations basic theories will be proposed to develop high-performance liquid crystalline polymer materials by really controlling the molecular chains in the liquid crystalline phase. Less
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