The dynamics of the surface height fluctuations on layers of covalently tethered, nearly monodisperse polymer chains synthesized by atom transfer radical polymerization were studied using X-ray photon correlation spectroscopy. The data reveal that both polystyrene and poly(n-butyl acrylate) "brushes" have structure at the surface with length scales in the region of 620-3100 nm, but the surface features show no relaxation in a time window of 0.1-1000 s, even at temperatures more than 130 °C above the glass transition temperature of the corresponding untethered chains. This remarkable alteration of the dynamics is compared with the suppression of fluctuations on this length scale anticipated by thermodynamic theories. The alteration of surface dynamics by tethering has implications for wetting, friction, and adhesion.

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The formation of af rustrated Lewis pair consisting of sodium hydride (Na +

Recent research on hydrogen storage in metal–organic frameworks focuses on how to achieve increased hydrogen binding energies by using doped metal, using unsaturated metal ions, or forming composites comprising Pt-doped carbon materials. In particular, noticeable progress using MOFs and Pt-doped carbons has been achieved to enhance the hydrogen storage capacity near room temperature. A three-component composite material, Pt-MWCNT-MOF5 (PMM5), which is a metal–organic framework (MOF-5) hybridized with Pt nanoparticles on multiwalled carbon nanotubes (MWCNT), stores 0.22 wt % hydrogen at 320 K and 30 bar, which is larger than 0.13 wt % at 300 K and 30 bar. Although the increased quantity is small, it is possible to detect the origin of uptake increase based on various analyses. In situ neutron diffraction experiments of deuterium-sorbed PMM5 with a temperature cycling process (D2 loading at 50 K → 4 K → 320 K, 2 h → 50 K → 4 K) result in a significant background increase owing to both chemisorbed deuterium atoms and a local deformation of the MOF-5 framework. Hydrogen loading in PMM5 induces significant binding energy shifts in C 1s and Zn 2p3/2 electrons in the X-ray photoelectron spectra, suggesting the chemical environment change in Zn4O(COO)6 coordination sphere in MOF-5. All accumulated experimental data support the fact that the hydrogen receptor is the oxygen atoms of benzene-1,4-dicarboxylates of MOF-5, which is facilitated by the embedded Pt-MWCNT.