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Synthesis and characterization of thermotropic liquid crystalline polyurethanes from 4,4′‐bis(6‐hydroxyhexoxy) biphenyl and aliphatic diols
Author(s) -
Wei Chun,
Gong Yongyang,
Yang Xianglian,
Wang Min
Publication year - 2009
Publication title -
polymers for advanced technologies
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.61
H-Index - 90
eISSN - 1099-1581
pISSN - 1042-7147
DOI - 10.1002/pat.1356
Subject(s) - thermotropic crystal , materials science , differential scanning calorimetry , liquid crystal , mesophase , thermogravimetric analysis , polarized light microscopy , fourier transform infrared spectroscopy , polyurethane , phase (matter) , diol , polymer chemistry , crystallography , chemical engineering , organic chemistry , composite material , chemistry , optics , liquid crystalline , thermodynamics , physics , optoelectronics , engineering
A series of thermotropic liquid crystalline polyurethanes (LCPUs) were synthesized by the polyaddition reactions of 2,4‐toluene diisocyanate (2,4‐TDI) with 4,4′‐bis(6‐hydroxyhexoxy)biphenyl (BHHBP) and aliphatic diol. The intrinsic viscosities of the polymers were measured by Ubbelohde viscometer, and the chemical structure was confirmed by Fourier transform infrared spectroscopy (FT‐IR). The LCPUs were examined by differential scanning calorimetry (DSC), polarized optical microscopy (POM), wide angle X‐ray diffraction (WAXD), and thermogravimetric analysis (TGA). The intrinsic viscosities were 0.56–0.83 dl/g. According to the melting point ( T m ) and the isotropic temperature ( T i ) of the LCPUs, the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyurethane. The LCPUs exhibited a nematic phase with a threaded texture and had a wide mesophase temperature range. The decomposition temperature of the LCPUs was >300°C. On WAXD, the LCPUs give a dispersing peak at 2θ ≈ 20°, and a strong diffraction peak at 2θ ≈ 25°. Copyright © 2008 John Wiley & Sons, Ltd.