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Effect of diisocyanate structures on the properties of liquid crystalline polyurethanes
Author(s) -
Lee Mooyoung,
Hong Sung Chul,
Lee SangWon
Publication year - 2007
Publication title -
polymer engineering and science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.503
H-Index - 111
eISSN - 1548-2634
pISSN - 0032-3888
DOI - 10.1002/pen.20684
Subject(s) - thermotropic crystal , polyurethane , materials science , differential scanning calorimetry , polymer chemistry , liquid crystalline , toluene diisocyanate , liquid crystal , polymer , composite material , physics , optoelectronics , thermodynamics
Thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized through the polyaddition reaction of 2,4‐toluene diisocyanate (2,4‐TDI), 4,4′‐diphenylmethane diisocyanate (MDI), or o ‐toluidine diisocyanate (ODI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl, and the effect of the structures of the diisocyanates on the properties of LCPUs were investigated. Intrinsic viscosities of the polymers were in the range of 0.23–0.30 dL/g. Mesomorphic behavior of the polyurethanes were investigated by differential scanning calorimetry, polarized optical microscopy, and wide‐angle X‐ray scattering. Different mesomorphic behaviors were observed according to the different structural characteristics of diisocyanates. Polyurethanes employing 2,4‐TDI and MDI exhibited monotropic behaviors, while that with ODI showed enantiotropic behavior. POLYM. ENG. SCI., 47:439–446, 2007. © 2007 Society of Plastics Engineers.