A series of poly(4,4'-biphenylenealkenylene)s and copolymers were prepared by the acyclic diene metathesis (ADMET) polymerization of 4,4'-bis(alkenylene)1,1'-biphenyls. Unsaturated polymers thus prepared were then hydrogenated to produce the corresponding saturated polymers. All the polymers were found to be thermotropic and to form solidlike smectic phases in melt. Their liquid crystallinity (LC) was studied by differential scanning calorimetry (DSC), X-ray diffractometry, and polarizing microscopy. We observed that one of the phenylene units of the biphenyl structure could selectively be hydrogenated at an elevated temperature. (C) 2004 Wiley Periodicals, Inc.