A novel series of Schiff base type liquid crystalline polymers with crown ether cycle was synthesized for the first time by solution polyeondensation from 4

4'-(alkylene dioyloxy) dibenzaldyhyde(M1)

cis-diamino-dibenzo-14-crown-4 (M2) and trans-cis-diamino—dibenzo-14-crown-4 (M3) as the monomers．Monomer M1 has been synthesized by esterifieation reaction of aliphatdiyl chloride and 4-hydroxybenzaldehyde．Monomers M2 and M3 have been synthesized by reduction reaction of cis-dinitrodibenzo-14-crown-4 and trans-dinitrodibenzo-14-crown-4 in the presence of 10％ Pd/C catalyst and hydrazine hydrate．The stereo structures of cis-(trans)-dinitredibenzo-14-crown-4 have been investigated by 1H-NMR

13C-NMR and molecular mechanics theory．It was found that the stereo structures of cis-trans-and dinitrodibenzo-14-crown-4 can be differentiated by 1H-NMR spectrum

approximately belonging to groups C8 and C2

respectively．The molecular weights of the polymers ale not high

and the Mn of the polymers ranges from 13000 to 24000．The monomer structures were identified by using elementary analysis

IR

1H-NMR and MS etc．The properties of polymem were investigated by using GPC

DSC

TG

WAXD and POM．It was found that all the polymers went into liquid-crystal phase when they were heated over their melting temperature (Tm)．The threaded texture and sehlieren texture Van be observed．The glass transition temperature(Tg)

melting temperature and isotropization temperature (Ti) change with varlng of the flexible spacer unit in the polymem．All the polymers have hish clearing points and wide mesophase range．The WAXD study illustrated that the polymers of PIb

Pld

PIIb and PIId are liquid crystalline with a nematie phase．A dispersive peak at 2θ near 20°appeared in their WAXD pettems

which is a typical character for quenched nematic liquid crystal polymem．