- Jiaping Lin , East China University of Science and Technology, Shanghai
Polypeptides, which bear rich conformations, are ideal building blocks for self-assembled nanostructures with complicated morphologies. By designing polypeptides with complex topological architectures, such as amphiphilic block and graft copolymers, we prepare various nano-aggregates, such as vesicles and spindle-like micelles. In addition to those typical aggregates, hierarchical nanostructures are also obtained. One way to realize hierarchy in self-assemblies is to introduce additional polymers into the polypeptide-based systems. For example, mixtures of poly(γ-benzyl L-glutamate)-block-poly(ethylene glycol) (PBLG-b-PEG) and PBLG homopolymers are able to form super-helices with determined chirality. Another way to prepare hierarchical aggregates is to adopt step-wise self-assembly strategy. For example, we found that the anisotropic spindle-like micelles formed by polypeptide graft copolymers can serve as pre-assembled subunits, which can further self-assemble into hierarchical structures, such as nanowires. The mechanism underlying the second step of this novel self-assembly behavior was found to follow the rule of step-growth polymerization. These results offer us potential pathway to design polymeric materials with desirable functions through controlled self-assembly.