The fabrication of hybrid hierarchical assemblies involving inorganic and organic building blocks has received a significant amount of attention as a result of their facile tunability and potential applications. However, precise design of hybrid hierarchical architectures still remains a challenge because of the difficulty of precise control over design and the incompatibility of organic and inorganic building blocks. Crystallization-driven self-assembly (CDSA) of block copolymers is a powerful method in the preparation of complex semicrystallized structures from the nano- to microscale, with controlled shape and uniform size. Herein, we extended the scope of this methodology in the construction of hybrid micellar CDSA brushes on functionalized carbon nanotubes (CNTs). Tunable brushlike heterostructures containing both CNTs and CDSA nanoassemblies were fabricated by anchoring the short crystalline seeds of PCL-b-P4VP [PCL = poly­(ε-caprolactone) and P4VP = poly­(4-vinylpyridine)] onto CNTs through the hydrogen bond and by a further in situ CDSA process via the addition of PCL-b-PDMA [PDMA = poly­(N,N-dimethylacrylamide)] unimers. More importantly, the shapes of PCL-b-PDMA crystals changed from two-dimensional platelets to long and thin crystals with increasing mass ratios of seed micelles to CNTs. Moreover, further exploration indicated that only one end of the immobilized seeds could initiate the growth of PCL-b-PDMA crystals, while the other end failed to enable growth because of the spatial confinement of CNTs.

Living crystallization-driven self-assembly (CDSA) is a powerful approach to tailor nanoparticles with controlled size and spatially defined compositions from amphiphilic crystalline block copolymers (BCPs). However, a variety of external constraints usually make the successful applications of living CDSA difficult. Herein, such constraints arising from strong hydrogen-bond (H-bond) interactions between unimers that lead to the failure of living CDSA are effectively overcome via reduction of the H-bond strength. In particular, by adding a H-bond disruptor trifluoroethanol (TFE), decreasing the unimer concentration, and reducing the corona segment length, the H-bond strength between unimers could be efficiently alleviated, leading to the formation of uniform two-dimensional (2D) platelets with controlled size and block comicelles with spatially defined corona chemistries. Moreover, by selectively anchoring one-dimensional (1D) seeds on the surface of as-prepared 2D block comicelles through H-bond interaction, the epitaxial growth of a crystalline BCP from immobilized 1D seeds on 2D platelets illustrates competitive growth behavior in a spatially confined environment.

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Although polymeric single crystals fabricated from self‐assembly of block copolymers are reported, preparation of single crystals with different aspect ratios still remains a major challenge. In this work, a facile way is demonstrated to prepare poly(ε‐caprolactone) based single crystals with tunable aspect ratios through simple counterion exchange on the basis of the Hofmeister series. Briefly, after ion exchange from Brˉ (an ion‐containing triblock copolymer, poly(ethylene oxide)‐b‐poly(ε‐caprolactone)‐b‐poly(quaternized 2‐(dimethylamino)ethyl methacrylate)/ethyl bromide (PEO‐b‐PCL‐b‐qPDM‐Br)) to more hydrophobic anions, Iˉ, SCNˉ, PF6ˉ and OTfˉ, respectively, morphological transitions from spheres to wormlike micelles and sphere to 2D platelet structure with an increasing aspect ratio are observed. The morphological transition depends on the essential hydrophilicity of the qPDM‐X segment and increasing crystallinity of the PCL core caused by ion exchange. These findings provide a facile approach to the preparation of polymeric single crystals with tunable aspect ratios.