Synthesis of liquid crystalline epoxy oligomers: Effect of molecular weight on the phase behavior

A series of epoxy-terminated liquid crystalline oligomers with different molecular weights having α-methylstilbene as the mesogenic unit were synthesized and characterized by means of 1H NMR and FT-IR spectroscopy, differential scanning calorimetry (DSC), polarized-light optical microscopy (POM) and X-ray diffraction. The effect of the initial ratio between epichlorohydrin and diol on the molecular weight was not significant enough to change the thermal behavior of the oligomers essentially. The copolymerization of epoxy- and hydroxyl-terminated comonomers yielded high-molecular weight oligomer, whose enantiotropic liquid crystalline character was proved by means of DSC, POM and X-ray diffraction.