The rigid-rod-like left-handed helical polyisocyanides (poly-3) with a different molecular weight and a narrow molecular weight distribution were prepared by the living polymerization of an enantiomerically pure phenyl isocyanide bearing an L-alanine pendant with an n-hexyl chain (3) using the mu-ethynediyl Pt-Pd catalyst. The left-handed helical poly-3s maintain their living feature and further copolymerized an analogous L-alanine-bound phenyl isocyanide with a long n-tetradecyl chain (4) to produce rod-rod diblock polyisocyanides with a controlled helical sense and a narrow molecular weight distribution. The rigid rod-rod helical diblock copolyisocyanides were composed of the same L-alanine pendants, but with alkyl chains of different lengths self-assembled to form the nanometer-scaled bilayer smectic-like ordering on a substrate and in a liquid crystalline state as evidenced by the direct atomic force microscopic and polarized optical micrograph observations, respectively.