New liquid crystals and liquid crystalline thermosets based on wholly aromatic rigid-rod mesogens

摘要

A series of new liquid crystals (LCs) and liquid crystalline thermosets (LCTs) were prepared from wholly aromatic mesogens containing 2,6-naphthalene diol (2,6-ND), 2,7-naphthalene diol (2,7-ND), hydroquinone (HQ), and biphenol (BP). Cross-linked LCTs were obtained by crosslinking their citraconimide reactive end groups under a range of heat treatment conditions. The LCs and cross-linked LCTs were characterized by Fourier transform infrared (FTIR) spectroscopy, 1H nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarizing optical microscopy (POM) with a hot stage, and wide angle X-ray diffraction (WAXD). All LCs were thermotropic and formed a Schlieren nematic texture. The LCTs did not exhibit a liquid crystalline mesophase, which indicates that they are non-mesogenic phases.