With object to evaluate the effect of spacer chemical composition on chain conformation of thermotropic polymers in liquid crystalline (LC) state, linear and combined (main chain/side chain) polymers, containing fragment of malonic acid (FMA) in methylene spacer were studied. It is shown that owing to presence of FMA chain conformations of the studied polymers differ substantially from those of RF-polymers with simple methylene spacer. In lc melt the main chain of polymers investigated has "hairpin"-like conformation with parallel allignment of neighbouring mesogens. In the case of combined polymers the side chain is located inside the hairpin, and mesogens of both main and side chains are found to be mutually parallel. Described polymer structure in LC melt provides the explanation for experimentally observed similarities between properties of LC melts of studied polymers and those of low molecular weight liquid crystalls.