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http://dx.doi.org/10.7473/EC.2013.48.2.141

Synthesis and Characterization of Liquid Crystalline Polyurethanes Containing Aromatic Ring Moiety  

Lee, Jong-Baek (Department of Chemical Engineering, Dongeui University)
Publication Information
Elastomers and Composites / v.48, no.2, 2013 , pp. 141-147 More about this Journal
Abstract
Polyurethanes containing no mesogenic unit were prepared by polyaddition reaction of homo- and copolyurethanes based on para-type 1,4-phenylene diisocyanate (1,4-PDI), 2,6-bis($\omega$-hydroxypentoxy)naphthalene (BHN5) with 1,4-bis($\omega$-hydroxypentoxy)benzene (BHB5). All copolyurethanes showed monotropic liquid crystallinity, when measurements were performed under shearing. For example, a polyurethane Poly(50/50, mol%) with $[\eta]$=0.32 dL/g exhibited liquid crystallinity in the temperature range from $223^{\circ}C$ to $211^{\circ}C$ in the cooling stage. In contrast, two homopolyurethanes exhibited no explicit mesomorphic behavior, which was observed by DSC (Differental Scanning calorimeter) and measurement and polarized microscopic observation. The mesomorphic behavior of synthesized polyurethane was identified and characterized by differential scanning calorimetry, polarized optical microscope and X-ray.
Keywords
polyurethane; liquid crystallinity; mesogenic unit; para-type diisocyanate;
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Times Cited By KSCI : 2  (Citation Analysis)
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