Noncovalent Functionalization of Graphene Nanosheets with Cluster-Cored Star Polymers and Their Reinforced Polymer Coating

Triblock Copolymer/Polyoxometalate Nanocomposite Electrolytes with Inverse Hexagonal Cylindrical Nanostructures

The primary issue of polymer electrolytes is to achieve high ion conductivity while retaining mechanical properties. A nanocomposite electrolyte with the inverse hexagonal cylindrical phase (three-dimensionally continuous domains for ion conduction and embedded domains for mechanical support) is prepared through the electrostatic self-assembly of a polyoxometalate (H₃ PW₁₂ O₄₀ , PW) and a triblock copolymer poly(N-vinyl pyrrolidone)-block-polystyrene-block-poly(N-vinyl pyrrolidone) (PSP). The cylindrical nanocomposite exhibits a conductivity of 1.32 mS cm^-1 and a storage modulus of 4.6 × 10⁷  Pa at room temperature. These two values are higher than those of pristine PSP by two orders of magnitudes and a factor of six, respectively. PW clusters are used as multifunctional nano-additives (morphological inducer, proton conductor, and nano-enhancer) and their incorporation achieves the simultaneous improvement in both conductive and mechanical performance.

Multiscale Self-Assembly of Mobile-Ligand Molecular Nanoparticles for Hierarchical Nanocomposites

Multiscale hierarchical morphologies are greatly desired for fabricating nanocomposites with tunable macroscopic properties, but challenges remain in precisely manipulating the spatial arrangement of nanoparticles in polymer matrices across multiple length scales. Here, we demonstrate a class of mobile-ligand nanoparticle system built upon 1 nm anionic polyoxometalate molecular nanoparticles and cationic terminated polymer chains by electrostatic interaction. The highly rearrangeable polymer chains can serve as mobile ligands to direct the polyoxometalates to align into sub-10 nm anisotropic superlattice-like nanoarrays in the bulk state. Moreover, these nanoarrays can further serve as structural units to assemble into hierarchically ordered morphologies in polymer matrices, e.g., percolated networks over hundreds of micrometers which are comprised of cylindrically packed polyoxometalate superlattices down to sub-10 nm scale. These hierarchical morphologies enable the nanocomposites with reinforced mechanical performance. The presented mobile-ligand approach can provide a paradigm to design functional polymer nanocomposites with improved properties such as mechanical reinforcement and collective optical and electronic functions.

Ionic Complexes of Metal Oxide Clusters for Versatile Self-Assemblies

The combination of rational design of building components and suitable utilization of driving force affords spontaneous molecular assemblies with well-defined nanostructure and morphology over multiple length scales. The serious challenges in constructing assemblies with structural advantages for the realization of functions programmed into the building components usually lie ahead since the process that occurs does not always follow the expected roadmap in the absence of external intervention. Thus, prefabricated intermediates that help in governing the target self-assemblies are developed into a type of unique building blocks. Metal oxide cluster polyanions are considered as a type of molecular nanoclusters with size scale and structural morphology similar to those of many known inorganic particles and clusters but possess distinctive characteristics. Following the understanding of these clusters in self-assembly and the rationalization of their most efficient design strategy and approach, the obtained fundamental principles can also be applied in common nanoparticle- and cluster-based systems. On the other hand, the deliberate synergy offered by organic countercations that support the self-assembly of these clusters greatly expands the opportunity for the functionalization of complex building units via control of multiple interactions. The ionic combination of the inorganic clusters with hydrophilicity and the cationic organic component with hydrophobicity leads to discrete properties of the complexes. Significantly, the core-shell structure with rigid-flexible features and amphiphilicity will pave the way for hierarchical self-assemblies of the obtained complexes, while the intrinsic characteristics of the metal oxide clusters can be modulated through external physicochemical stimuli. Within this context, over the past decade we have extensively explored the ionic combination of inorganic polyanionic clusters with cationic organic amphiphiles and devoted our efforts to establishing the general rules and structure-property relationships of the formed complexes for constructing self-assemblies at the interface, in solution, and in solid matrixes. Specific interest has been focused on the functional synergy deriving from the incompatible components in highly organized self-assemblies. In this Account, we describe the recent progress on the ionic complexation of polyoxometalate clusters with cationic amphiphiles and the construction of diverse self-assembled nanostructures. First, the fundamental structural characteristics and molecular geometries of the prepared complexes are analyzed. The construction principle and diversity of the self-assembly based on the complexes and the smart stimuli response are then discussed, subject to the adjustment of various non-covalent interactions occurring in the assemblies. Subsequently, we enumerate the functional applications of the ionic complexes assembling into organic, inorganic, and even biological matrixes. The inspiration from the construction of ionic complexation and self-assembly in this Account provides vivid profiles for the design of hybrid materials involving nanoclusters and/or nanoparticles with rich potentials in addition to polyoxometalate chemistry.

Photoredox-Mediated ATRP: A Facile Method for Modification of Graphite Fluoride and Graphene Fluoride without Deoxygenation

Graphite fluoride (GiF) and graphene fluoride (GeF) showed interesting electrochemical, electronic, and mechanical properties in comparison with their derivatives of graphite and graphene, respectively. Due to the chemical inertness of GiF and GeF, as far as we are aware, no report can be found on the modification of GiF and GeF with polymeric chains. Herein, we reported that photoredox-mediated atom transfer radical polymerization (ATRP) is able to directly introduce methacrylate-based polymers, including poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMA), poly(methyl methacrylate) (PMMA), poly(pentafluorophenyl methacrylate) (PPFMA), and poly(methacrylic acid) (PMAA), onto the surface of GiF and GeF by utilizing C-F bonds of GiF and GeF as initiating sites and Ir(ppy)₃ as a photoredox catalyst under low intensity blue LED light strips (10 W, 460-470 nm) in DMF for graft polymerization without a tedious deoxygenation procedure. Owing to the attractive properties of GiF and GeF, along with the capacity of spatial control over the formation of polymeric chains on the surface of GiF and GeF endowed by the inherent nature of photoredox-mediated ATRP, there is no doubt that the strategy developed in the current work shows a great potential in the preparation of polymer-decorated GiF and GeF and the corresponding functional materials.

POM species, temperature and counterions modulated the various dimensionalities of POM-based metal–organic frameworks

A series of six POM-based metal–organic frameworks with various dimensionalities have been isolated by tuning the reaction conditions (POM species, reaction temperature and counterions).

Versatile self-assembly of supramolecular block copolymers with ionic cluster junctions

Clusto-supramolecular block copolymers were prepared by using an inorganic cluster [W₆O₁₉]²⁻ as an ionic junction, which exhibited versatile self-assembly behaviours.