Side-chain liquid-crystalline polymers were synthesized using malonic acid esters with a mesogenic group (1) linked through a hexamethylene spacer and oligo(ethy1ene glycol) (2.) as a flexible mainchain spacer. Polymers derived from 1 with a mesogen such as p-nitrophenylazophenoxy (la) or 4-(4'-nitro-phenylviny1ene)phenoxy group (lb) form stable mesophases over a wide temperature range, though the increase of chain length of 2. decreases the thermal stability of the liquid-crystalline (LC) phases. LC polymers were obtained from 1 with a mesogen with p-substituted biphenoxy groups only when 2. with shorter chain length is employed. Copolymerizations were undertaken to see the effect of monomer pairs and copolymer compositions on the phase transition behavior of the copolymers formed, using three monomer pairs, l a and 1 with the p-methoxybiphenoxy group as the mesogen, l a and lb, and l a and 1 with the p-nitrobiphenoxy group as the mesogen. The copolymers formed from the first pair display a nematic phase over a much wider temperature range than the respective homopolymers. This was ascribed to the electron donor-acceptor interaction between the two mesogens in the monomer pair. R 1 1 R (Scheme l), since 2. chain is one of the most flexible chains. The roles of the mesogenic group and the chain length of 2. unit required to achieve a liquid crystallinity were examined. Mesogenic monomers, 1, have already