A new type of low-molecular-weight polypyrimidine in a π-conjugated main chain was prepared by a Grignard reaction between 2-amino-4,6-dichloropyrimidine and 1,4-dibromo-2,5-didodecyloxybenzene in the presence of [1,2-Bis(diphenylphosphino) ethane]dichloronickel(II). The structure of the copolymer was fully elucidated by Fourier transform infrared spectroscopy, 1H-NMR, and elemental analysis. The copolymer had good solubility in common organic solvents. The copolymer displayed a bathochromic shift when protonated with an organic or inorganic acid in chloroform or tetrahydrofuran. The copolymer depicted facile p-doping and good electron-transporting electrochemical properties in a 1M H2SO4 aqueous solution. The copolymer showed a narrow polydispersity of 1.04. Thermogravimetric analysis showed that the copolymer had a certain thermal stability with no decomposition at a temperature of 250°C under N2. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41174.