Two random copolymers, poly(p-phenylenevinylene-co-2,5-didodecyloxy-p-phenylenevinylene) and poly(2,5-dimethoxy-p-phenylenevinylene-co-2,5-didodecyloxy-p- phenylenevinylene), were synthesized via the chlorine precursor route followed by thermal elimination. One alternating copolymer, poly(p-phenylenevinylene-alt-2,5-didodecyloxy-p- phenylenevinylene), was prepared via the Heck coupling reaction. The effects of molar ratio of monomers on yield and composition of the precursor copolymers were studied. The two precursor copolymers and the alternating copolymer were characterized by gel permeation chromatography, differential scanning calorimetry, elemental analysis, and infrared spectroscopy. The UV-visible absorption spectra and photoluminescence spectra, as well as solubility and conductivity of these copolymers, were compared.