A peptide-synthetic hybrid block copolymer, poly(ethylene oxide) -block-poly(L-glutamic acid), is shown to form supramolecular complexes with primary alkylamines of varying alkyl chain lengths (8 to 18 methylene units) in organic solvents via acid-base proton transfer and subsequent ionic bonding. The peptidic block being in the a-helical conformation, these materials behave as coil-'' hairy rod '' block copolymers, and show hierarchically self-organized nanostructures in the solid state. X-ray scattering measurements show mesomorphic behavior at the length scales of both the overall block copolymer and the polypeptide-alkylammonium complex.