ISSN:
1013-9826
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
A new type of thermotropic main-chain liquid crystalline polyurethanes containingbiphenyl units was synthesized by polyaddition reaction of diisocyanates such as 2,6-tolylenediisocyanate, 2,5-tolylene diisocyanate, 2,4-tolylene diisocyanate, and 1,4-phenylene diisocyanate,with 4,4′-Bis(8-hydroxyoctoxy)biphenyl (BP8). The structure of the monomer and thecorresponding polymers were confirmed using FT-IR and 1H-NMR spectroscopic methods. BP8exhibited a smectic type mesophase, however, nematic phases were found for all synthesized liquidcrystalline polyurethanes except for 1,4-phenylene diisocyanate/BP8 based polyurethane. Forexample, polyurethane 2,5-TDI/BP8 exhibited monotropic liquid crystallinity in the temperatureranging from 172 to 160 °C on the cooling stage. Properties of these polyurethanes were studied bydifferential scanning calorimetry (DSC), and optical polarizing microscopy. The FT-IR studyindicated that the hydrogen bonding among urethane linkages attributed to the mesomorphism
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/01/54/transtech_doi~10.4028%252Fwww.scientific.net%252FKEM.342-343.729.pdf
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