Polyethers with p-alkoxyphenyl groups in the side chain (PEn) were prepared by ring opening polymerization of the corresponding glycidyl ether derivatives. These polyethers exhibited highly ordered smectic phase depending upon the alkoxy chain length. A liquid crystalline phase was formed at the alkoxy chain length of below 12. The mesomorphic properties for the mixed system were originated from adding an alkali metal salt into the non-mesomorphic side chain type polyethers. The mesomorphic temperature range for the mixed system was wider with increasing amount of alkali metal salt. The occurrence of the complexed the side chain type polyethers with the alkali metal salt was confirmed by Raman spectroscopy and X-ray photoelectron spectroscopy measurements (XPS).