Hierarchically structured materials derived from synthetic polymers: design and bulk self-assembly strategies

Abstract

Hierarchical structures are ubiquitous in biological systems—proteins, for instance, achieve complex and precise assemblies through the hierarchical organization of amino acid sequences, enabling diverse and sophisticated functions. Inspired by nature, hierarchically structured synthetic polymers have emerged as a new class of materials capable of forming ordered morphologies with multiple periodicities, surpassing the conventional phase behavior of linear diblock copolymers. This review critically summarizes recent progress in the design and formation of hierarchical structures in synthetic polymers. We categorize current strategies into five major approaches: (1) multiblock copolymers, (2) supramolecular assemblies, (3) liquid crystalline copolymers, (4) polypeptide-based copolymers, and (5) graft/bottlebrush block copolymers. Particular attention is given to approaches that employ diverse macromolecular architectures, including linear, star, and bottlebrush polymers, to access complex morphologies. In addition, we highlight recent advances in polymer-grafted nanocrystals, which give rise to hierarchical superlattices by integrating atomic-level ordering from the nanocrystals with nanoscale periodicity from the polymer corona. We conclude by discussing emerging synthetic directions and potential applications of these hierarchically structured polymeric materials.