Controllable One‐Step Assembly of Uniform Liquid Crystalline Block Copolymer  Cylindrical Micelles via Tailored Nucleation‐Growth Process and Their Applications as Tougheners

The fabrication of uniform cylindrical nanoobjects from soft materials has attracted tremendous research attention from both fundamental research and practical application points of view but also posed outstanding challenges to their preparation. Herein, we report a one‐step method to assemble cylindrical micelles (CMs) with highly controllable lengths from a single liquid crystalline block copolymer via an in‐situ nucleation‐growth strategy. By adjusting the assembly conditions, the lengths of the CMs are controlled from hundreds of nanometers to microns. Several influencing factors are systematically investigated to comprehensively understand the process. Particularly, the solvent quality is found determinative to either enhance or suppress the nucleation process to produce shorter and longer CMs, respectively. Taking advantage of this strategy, the lengths of CMs can be nicely controlled in a wide concentration range over four magnitudes. Lastly, CMs are produced on decent scales and applied as additives to dramatically toughen glassy plastic matrix, revealing an unprecedented length‐dependent toughening effect.