A novel phosphorus-containing thermotropic liquid crystalline copolyester with kinked unit named as poly(hydroxybenzate-co-DOPO-benzenediol dihydrodipheyl ether terephthalate) (PHDDT) was synthesized successfully by melting transesterification from terephthalic acid (TPA), p-hydroxybenzoic acid (p-ABH), 2-(6-oxid-6H-dibenz(c, e) (1,2) oxaphosphorin 6-yl)1,4-benzenediol (DOPO-HQ), and 4,4 0 -dihydroxydiphenyl ether (DOP). The chemical structure, the mesophase behavior, and the thermal properties of the copolyesters were characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy ( 1 H, 13 C, and 31 P NMR), wide-angle X-ray diffraction, polarizing light microscopy (PLM), differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical analysis. Results suggested that PHDDTs exhibited the typical nematic mesophase that occurred at low temperatures and maintained in a broad temperature range from 230 C to higher than 400 C, and had low glass transition temperature ranging from 154.5 to 166.9 C. The novel phosphorus-containing thermotropic liquid crystalline copolyester will have a potential application in preparing various in situ reinforced polymer materials with excellent mechanical properties and flame retardancy.
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