Geometry-Modulated Self-Assembly Structures of Covalent Polyoxometalate–Polymer Hybrid in Bulk and Thin-Film States

Abstract

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.

Recent research progress on polyoxometalate-based electrocatalysts in energy generation

“…73 POM-based nanostructures can be synthesized using various methods, such as solution-based synthesis, template-assisted fabrication and self-assembly. [74][75][76] Depending on the synthesis conditions and assembly techniques, the resulting POM-based nanostructures can exhibit different morphologies, including nanoparticles, nanowires, nanotubes and thin lms. [77][78][79][80] Their size, shape and composition can be precisely controlled, enabling customized properties and functionalities.…”

Precise Assembly of Polyoxometalates at Single‐cluster Levels

“…In addition, three kinds of Keggin‐type POM‐PS n (PS=polystyrene) hybrid building blocks were fabricated through click chemistry (Figure 5e). [51] In bulk state, the self‐assembly of KPOM‐PS n results in lamellae (LAM) or hexagonal packed cylinders (HEX) structures with mostly sub‐10 nm feature sizes, while KPOM‐2PS n and KPOM‐3PS n favor the formation of the spherical body‐centered cubic (BCC) and disordered micelles (DM) phases. LAM, HEX and BCC structures can be observed in the thin‐film state in both cases.…”