New aromatic-aliphatic polyethers containing alkyl- or alkoxy-substituted oligophenyl units were synthesized. The polyethers were characterized by viscosimetry, gel permeation chromatography, thermal and mechanical analysis, NMR, and UV-vis luminescence spectroscopy. The type of the side chain as well as the length of the flexible spacer influence the thermal and mechanical behavior of the synthesized polyethers. In all examined cases, the isotropization transition as well as the glass transition temperature show an odd-even effect depending on the spacer segment length. The polymers are soluble in common solvents and form free-standing films that combine high modulus (E＇) at room temperature with blue photoluminescence. High fluorescence quantum yield (phi = 0.82) was obtained for the polyethers studied, which is comparable to values reported in the literature for substituted poly(p-phenylenes). The type of the substitutent affects the maximum of the fluorescence peak, which is in the range 370-430 nm.