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Synthesis and properties of liquid crystalline polyurethane elastomers
Author(s) -
Lee TaeJung,
Lee DongJin,
Kim HanDo
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(20000718)77:3<577::aid-app13>3.0.co;2-x
Subject(s) - polyurethane , mesogen , materials science , glass transition , liquid crystal , elastomer , polymer chemistry , prepolymer , liquid crystalline , composite material , chemical engineering , polymer , optoelectronics , engineering
Novel type of mesogenic chain extenders used in this study are N , N ′‐bis(4‐hydroxyphenyl)‐3,4,3′,4′‐biphenyldicarboxyimide (BPDI) and N , N ′‐bis[4‐(6‐hydroxyhexyloxy) phenyl]‐3,4,3′,4′‐biphenyldicarboxyimide (BHDI). BHDI has a flexible spacer of 6‐methylene units but BPDI does not. The liquid crystalline polyurethane elastomers were synthesized from BPDI or BHDI as a mesogenic chain extender, 4,4′‐diphenylmethane diisocyanate, and poly(oxytetramethylene)glycol (MW 1000) as a soft segment. Polyurethane based on BHDI exhibited two melting transitions. However, any melting behavior was not shown in the BPDI‐based polyurethanes because of higher melting temperature than decomposition temperature. The composition of polyurethanes was varied as a means of manipulating liquid crystalline behavior and physical properties. The BHDI‐based polyurethanes containing above 50 wt % of hard segment content exhibited nematic liquid crystal behaviors. As the hard segment content of the BHDI‐based polyurethanes increased, the glass transition temperature ( T g ), strength, modulus, and the amount of hydrogen bonding increased. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 577–585, 2000