In this article, the synthesis of a series of conjugated rod-rod block copolymers based on poly(3-hexylthiophene) (P3HT) and poly(phenyl isocyanide) (PPI) building blocks in a single pot is presented. Ni-catalyzed Grignard metathesis polymerization of 2,5-dibromo-3-hexylthiophene and subsequent addition of 4-isocyanobenzoyl-2-aminoisobutyric acid decyl ester in the presence of Ni(dppp)Cl2 as a single catalyst afford P3HT-b-PPI with tunable molecular weights and compositions. In solid state, microphase separation occurred as differential scanning calorimetric analysis of P3HT-b-PPI revealed two glass transition temperatures. In solutions, the copolymers can self-assemble into spherical aggregates with P3HT core and PPI shell in tetrahydrofuran and exhibit amorphous state in CHCl3. However, atomic force microscopy revealed that the block copolymers self-assemble into nanofibrils on the substrate. These unique features warrant the resultant conjugated rod-rod copolymers' potential study in organic photovoltaic and other electronic devices. (c) 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2939-2947