Liquid crystalline( LC) thermotropic main-chain polyesters and copolyesters based on 4,4＇-dihydroxy-alpha-methylstilbene (mesogen) and azelaoyl chloride (flexible spacer) and 10,12-docosadiynedioyl chloride [ultraviolet (UV)-crosslinkable moiety ] were synthesized by interfacial polymerization. Improvement of molecular weight was achieved by the modification of interfacial polymerization. Molecular weights of the LC polymers ranged from 13,000 to 56,500 g/mol(-1), depending on composition of the LC polymers. Mesomorphic properties of these polymers were studied, and phase diagrams were established. Polymers showed nematic and smectic mesophases, depending on the flexible spacer composition. UV-crosslinking of the LC polymers containing W-sensitive diacetylenic groups was attempted, and crosslinked LC polymer films were obtained. Mechanical properties of LC polymer films were also studied with a dynamic mechanical analyzer. The storage moduli of the polymer films, depending on the molecular weight of the polymers, increased by the W-crosslinking. Higher molecular weights and crosslinking were favorable for the higher storage moduli of the films. The effect of orientation on the mechanical properties was also studied, and it was found that orientation induced the increase of the moduli of the films.