EDGE ARTICLEPanchao Yin et al. Poly(ethylene glycol) nanocomposites of sub-nanometer metal oxide clusters for dynamic semi-solid proton conductive electrolytes Sub-nm-scale metal oxide clusters (PW 12 O 40 3À) show high solubility in the melt of poly(ethylene glycol) (PEG) and the obtained semi-solid nanocomposites show promising proton conductivities under ambient conditions. Suggested from scattering studies, the clusters are homogeneously dispersed in the PEG melt at the molecular scale with high loading amounts (70 wt%) and the formed real solutions can be stable for months with no aggregation or phase separation. The conductivities of the nanocomposites which are governed by the concentrations of H 3 PW 12 O 40 can reach as high as 1.01 Â 10 À2 S cm À1 at the highest concentration. Due to the dynamic cross-linking hydrogen bonding between clusters and PEG, the nanocomposites behave like solids with negligible flow at high concentrations of clusters. Upon the application of high-speed shear forces (>32 s À1 ), the composites can flow with continuously decreasing viscosities. The shear thinning properties of the nanocomposites enable their convenient processing into required morphologies and the wettability of electrolytes to electrodes under typical high shear rate processing conditions and the safety of the produced devices can be ensured by their solid-like properties in the static state. † Electronic supplementary information (ESI) available: Details of the d-cals calculation method, IR and impedance spectra, ow curves, relationship between the shear rate and stress, viscosities and volume fraction of POMs, cyclic curves of shear rate and shear stress, E a of the nanocomposites, DLS data and the tting curves of ow curves. See

PIn/RGO nanocomposite prepared by in stiu chemical polymerization shows specific capacitance of 322.8 F g−1 at 1.0 A g−1, good stability of 94.5% retention after 1000 cycles, and high energy density of 36 W h kg−1 at high power density of 5000 W kg−1.

Monodispersed hairy nanocomposites with typical 2 nm (isophthalic acid)24Cu24 metal–organic polyhedra (MOP) as a core protected by 24 polymer chains with controlled narrow molecular weight distribution has been probed by imaging and scattering studies for the heterogeneity of polymers in the nanocomposites and the confinement effect the MOPs imposing on anchored polymers. Typical confined‐extending surrounded by one entanglement area is proposed to describe the physical states of the polymer chains. This model dictates the counterintuitive thermal and rheological properties and prohibited solvent exchange properties of the nanocomposites, whilst those polymer chain states are tunable and deterministic based on their component inputs. From the relationship between the structure and behavior of the MOP nanocomposites, a MOP‐composited thermoplastic elastomer was obtained, providing practical solutions to improve mechanical/rheological performances and processabilities of inorganic MOPs.

Materials under space confinement can alter their physical and chemical properties, paving the way for new science and novel applications. Nanoparticles can enforce spatial constraints on the polymers densely grafted on their surfaces, which can effectively change polymers’ thermal/mechanical properties and finally lead to significant mechanical reinforcement for the obtained nanocomposites. Here, we describe the confinement effect that metal–organic polyhedron (MOPs), nanoparticles with monodispersed and ultrasmall sizes (∼2 nm), impose to the 24 poly­(N-isopropylacrylamide) (PNiPAM) chains grafted on their surface. The curved surface of the MOP brings unique confinement to the grafted PNiPAMs: the inner fraction of PNiPAM chains is under ultraconfinement, while the outer fraction is almost free. Suggested from small angle neutron scattering studies, the outer layer polymers stay hydrated and help solvate the nanocomposites in water, while the inner polymer layer prohibits the water penetration into MOP area and contributes to the high stability of the MOPs. Such a confinement effect further influences the thermoresponsiveness of PNiPAM–MOPs in solutions and enhances their efficiency for controlled separation and release of small molecules.

Films that can maintain their flexibilities and conductivities under low humidity and broad temperature range represent the next generation of solid-state proton conductors, which would extend the applications of energy storage and conversion devices in extreme environments. Owing to their strong interactions with poly­(ethylene oxide) (PEO), polyoxometalates (POMs), a group of nanoscale metal oxide clusters, can form stable nanocomposites with PEO and fully inhibit its crystallization, facilitating the fast dynamics of PEO chains/segments, as evidenced from dielectric spectroscopy studies. It thus enables the fast proton transportation in the PEO matrix and the improvement of the composites’ proton conductivities. With POMs’ loading ratio approaching to 70% wt, the nanocomposite’s proton conductivity reaches as high as 6.86 × 10–3 S cm–1 at 100 °C in anhydrous environment. The composites’ mechanical properties can be further optimized upon the tuning of PEOs’ molecular weight and finally, a flexible, self-supported anhydrous proton conductor can be obtained, which also demonstrates high compatibility to electrodes. The nanocomposite can maintain promising proton conductivities ranging from −20 to 100 °C in an anhydrous environment, enabling the fabrication of long-term robust performance of supercapacitor devices under extreme conditions, which has never been achieved before.