The performance of 2D nanomaterials hinges on both the chemical compositions and the morphological structures across different length scales. Among all the three dimensions, thickness is the only one that...

Side-chain giant molecules, constructed from giant monomers by precision synthesis, are viewed as a size-amplified analogue of conventional linear polymers. The molecular accuracy in terms of composition, sequence, topology, and functionality makes these precise macromolecules an ideal platform to investigate the interplay of various molecular parameters in their hierarchical assembly processes. In this study, we studied the crystallization of two sets of amphiphilic side-chain giant molecules with elegantly designed chain sequences and functionalities. When crystallizing from dilute solutions, they form well-defined two-dimensional (2D) crystals with a unique sequence-independent feature. In-depth structural characterization suggested a sandwich-like configuration with head-to-head packing of the side-chain components. Interestingly, the chain stem orientation is supposed to be perpendicular to the normal direction of the nanosheet crystals, which was distinct from the classic folded-chain model of conventional linear polymers. Besides, by intentionally altering the functional groups of the non-crystalline moieties to be non-ionic, cationic, or anionic, we proposed that the solvation effect played a key role in inhibiting the crystal stacking along the surface normal direction and thus in stabilizing the 2D crystals. Our findings revealed the unique crystallization behavior of precise side-chain giant molecules and might provide a strategy to engineer 2D nanomaterials with pre-programmed compositions and functions.

It remains intriguing whether macromolecular isomerism, along with competing molecular interactions, could be leveraged to create unconventional phase structures and generate considerable phase complexity in soft matter. Herein, we report the synthesis, assembly, and phase behaviors of a series of precisely defined regioisomeric Janus nanograins with distinct core symmetry. They are named B2DB2 where B stands for iso-butyl-functionalized polyhedral oligomeric silsesquioxanes (POSS) and D stands for dihydroxyl-functionalized POSS. While BPOSS prefers crystallization with a flat interface, DPOSS prefers to phase-separate from BPOSS. In solution, they form 2D crystals owing to strong BPOSS crystallization. In bulk, the subtle competition between crystallization and phase separation is strongly influenced by the core symmetry, leading to distinct phase structures and transition behaviors. The phase complexity was understood based on their symmetry, molecular packing, and free energy profiles. The results demonstrate that regioisomerism could indeed generate profound phase complexity.

We applied chromatographic and spectroscopic techniques to revisit the product distribution of the corner-opening and corner-capping reactions of monosubstituted T8 POSS. The monosubstituted Si is more likely to be removed...

This work reports the synthesis, characterization, and self-assembled structures of three series of Keggin-type polyoxometalate (POM)-based hybrid molecules KPOM- m PS n ( m = 1, 2 and 3), in which one, two, or three polystyrene (PS) chains are covalently attached to a POM head, respectively. The classical “click” reaction was applied to prepare samples with predesigned molecular geometry, which were further purified by C18 reversed-phase high-performance liquid chromatography (RP-HPLC). Strong chemical incompatibility between inorganic POMs and organic PS chains drives the hybrid molecules to microphase separate into versatile nanostructures in both bulk and thin-film states. In thermally annealed bulk samples, four phase morphologies were found depending on both the overall molecular geometry and the volume fractions of PS tails, including lamellae (LAM), hexagonal packed cylinders (HEX), disordered micelles (DM), and body-centered cubic (BCC) packed spheres, as revealed by small-angle X-ray scattering (SAXS). In the thin-film state, LAM, HEX, and BCC structures were observed and proved by transmission electron microscopy (TEM) images and grazing incidence SAXS (GISAXS). This work expands the scope of self-assembled nanostructures of POM-based hybrid materials to spherical phases and provides a platform for the study of the basic physical principles of their self-assembly behavior.

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