Self-assembled structures in rod-coil block copolymers with hydrogen-bonded amphiphiles

We report the synthesis and the self-assembled morphologies of a series of new rod-coil diblock copolymers, poly[2,7-(9,9-dihexylfluorene)]-b-poly(4-vinylpyridine) (PF-b-P4VP). The rod-coil diblock copolymers were synthesized via Suzuki coupling reaction and living anionic polymerization. Probing by transmission electron microscopy, small-angle X-ray scattering and atomic force microscopy, we found that the microphase separation varies from lamellar to cylindrical and then to spherical, depending on the length of P4VP blocks. The P4VP coil blocks were further hydrogen-bonded with 3-pentadecylphenol (PDP) to form rod-comb block copolymers. Similar to conventional coil-coil block copolymers-based supramolecules, the incorporation of PDP transforms the morphologies from lamellar to cylindrical or from cylindrical to spherical due to the increase of volume fraction of P4VP(PDP) comb blocks. The strategy described here can be used to tune the self-assembled structures of rod-coil block copolymers.