Liquid-Crystallization-Driven Self-Assembly toward Uniform Multi-Morphology Fried-Egg-Like Nanostructures

Liquid-crystallization-driven self-assembly (LCDSA) has recently emerged as an efficient strategy to create uniform one-dimensional (1-D), 2-D and 3-D nanostructures in a controlled manner. However, the examples of generation of uniform multi-morphology nanostructures from solution self-assembly of one single polymer sample are rare. Herein, we report the first example of preparation of multi-morphology fried-egg-like nanostructures consisting of an inner spherical/bowl-like core of uniform size and platelets protruded from the core by LCDSA of PAMAM-Azo₆ (PAMAM=polyamidoamine, Azo=azobenzene) in methanol. It is disclosed that the different aggregation rates for PAMAM-Azo₆ with varying contents of Azo units spontaneously separated nucleation and growth stages, which led to the formation of inner spherical/bowl-like cores ("seeds") firstly, followed by the formation of platelets protruded from the edges of inner core to give "imperfect" fried-egg-like nanostructures. Additional annealing of initially formed "imperfect" fried-egg-like micelles will promote the rearrangement of Azo units to give thermodynamically-favored "perfect" fried-egg-shaped micelles with a uniform dimension both in the core and whole structure. This work not only provides an efficient strategy to create uniform multi-morphology fried-egg-shaped nanostructures, but also reveals the essential impact of aggregation kinetics of liquid-crystalline-coil BCPs in the formation of multi-morphology nanostructures.