TY - JOUR
T1 - Synthesis and mesomorphism of thermotropic liquid crystalline polyurethanes based on meta-diisocyanates with 4,4′-bis(ω-hydroxyalkoxy) biphenyls
AU - Lin, Chien Kung
AU - Kuo, Jen Feng
AU - Chen, Chuh Yung
N1 - Funding Information:
This work is supported by a grant from the National Science Council of the Republic of China (Taiwan) with contract NSC 87-2216-E-006-007. Thanks are due to Miss S.Y. Li, The Institute of Material Science, National Sun Yat Sen University, Kaousiung, for the assistance in the measurements of wide angle X-ray diffraction spectra.
PY - 2000
Y1 - 2000
N2 - There are two series of novel thermotropic liquid crystalline polyurethanes (LCPUs), obtained from the polyaddition reaction of 4,4′-bis(ω-hydroxyalkoxy) biphenyls (HBn, n: the number of methylene units in hydroxyalkoxy group) with 1,3-bis(isocyanatomethyl) benzene (XDI) and 1,3-bis(isocyanatomethyl) cyclohexane (H6XDI), respectively. The Fourier transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, polarizing optical microscope and thermogravimetric analysis were used for characterizing these polyurethanes. All of the liquid crystalline polyurethanes exhibited enantiotropism. Except that XDI/HB11 showed trimorphism, all the other polyurethanes presented monomorphism in this study. The H-bonded urethane domain is stronger when the polyurethanes are composed of the benzene ring urethane moiety and longer alkoxy chain, and they show a higher transition temperature associated with the better stability in mesophase. All the thermal degradation of LCPUs are higher than 330°C. The polyurethanes of H6XDI/HB2 and XDI/HB2 show one-step degradation, while the others show two-step degradation.
AB - There are two series of novel thermotropic liquid crystalline polyurethanes (LCPUs), obtained from the polyaddition reaction of 4,4′-bis(ω-hydroxyalkoxy) biphenyls (HBn, n: the number of methylene units in hydroxyalkoxy group) with 1,3-bis(isocyanatomethyl) benzene (XDI) and 1,3-bis(isocyanatomethyl) cyclohexane (H6XDI), respectively. The Fourier transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, polarizing optical microscope and thermogravimetric analysis were used for characterizing these polyurethanes. All of the liquid crystalline polyurethanes exhibited enantiotropism. Except that XDI/HB11 showed trimorphism, all the other polyurethanes presented monomorphism in this study. The H-bonded urethane domain is stronger when the polyurethanes are composed of the benzene ring urethane moiety and longer alkoxy chain, and they show a higher transition temperature associated with the better stability in mesophase. All the thermal degradation of LCPUs are higher than 330°C. The polyurethanes of H6XDI/HB2 and XDI/HB2 show one-step degradation, while the others show two-step degradation.
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U2 - 10.1016/S0014-3057(99)00164-0
DO - 10.1016/S0014-3057(99)00164-0
M3 - Article
AN - SCOPUS:0001323377
VL - 36
SP - 1183
EP - 1193
JO - European Polymer Journal
JF - European Polymer Journal
SN - 0014-3057
IS - 6
ER -