Hierarchical Smectic Self-Assembly of an ABC Miktoarm Star Terpolymer with a Helical Polypeptide Arm

We demonstrate the first hierarchical smectic self-assembly in miktoarm star terpolymers, using a polymer/polypeptide hybrid (macromolecular chimera) composed of two coil-like arms (polystyrene, PS, and polyisoprene, PI) and a mesogenic a-helical polypeptide arm (poly(epsilon-tert-butyloxycarbonyl-L-lysine), PBLL). The PBLL alpha-helices are packed within lamellar nanodomains which leads to an overall smectic alteration of rod- and coil-containing layers typically observed in rod coil block copolymers. Furthermore, the coil-containing lamellae have an inner structure composed of PS and PI rectangular cylinders, leading to what we call a hierarchical smectic phase. To elucidate the role of polypeptide helices in directing the self-assembly, the ordering is studied both after thermal annealing and after quick drop-casting from chloroform solution. The possibility to combine mesogen packing, tiling patterns, and conformational control of polypeptide blocks makes self-assembled hierarchies of star-shaped macromolecular chimeras appealing for future studies.