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Encapsulation behavior, as well as the presence of internal catalytically active sites, has been spurring the applications of a 3 nm hollow spherical metal oxide cluster {Mo132} as an encapsulation host and a nanoreactor. Due to its well-defined and tunable cluster structures, and nanoscaled internal void space comparable to the volumes of small molecules, this cluster provides a good model to study the dynamics of materials under nanoconfinement. Neutron scattering studies suggest that bulky internal ligands inside the cluster show slower and limited dynamics compared to their counterparts in the bulk state, revealing the rigid nature of the skeleton of the internal ligands. NMR studies indicate that the rigid internal ligands that partially cover the interfacial pore on the molybdenum oxide shells are able to block some large guest molecules from going inside the capsule cluster, which provides a convincing protocol for size-selective encapsulation and separation. [ABSTRACT FROM AUTHOR]

The characteristic nanoscale dynamics of the alkyl side groups in the light‐emitting polymer poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylene vinylene] have been investigated using quasi‐elastic neutron scattering (QENS). The measurements were taken below the polymer's glass transition (T ≤ Tg ≃ 353 K), where the main backbone is in a rigid state and does not contribute to the broadening of the QENS signal. An analytical diffusion model consisting of a static term and two dynamical components, characterizing the flexible side groups, provide an excellent fit to the experimental data. The two observed dynamical processes are all localized in character, with no meaningful dependence on temperature. The faster process, with characteristic timescale of ∼18 ps at room temperature (RT), can be linked to the average mobility of the terminal protons of the alkyl chain, while the slower process, with characteristic timescale of ∼170 ps at RT, to those protons at the other end of the alkyl chain, closest to the backbone. While the fraction of mobile protons contributing to the QENS signal increases with increasing temperature, the characteristic timescale and confining volume within which the protons are able to move locally depend chiefly on the polymer conformational state. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47394. [ABSTRACT FROM AUTHOR]

The nanoconfinement effect defined by the polyoxometalate nanocage renders the encapsulated bulky ligands rigid properties by significantly limiting and slowing down their diffusive motions. These ligands that partially cover the interfacial pore on the molybdenum oxide shells are able to block some large guest molecules from going inside the capsule cluster, which provides a convincing protocol for size‐selective encapsulation and separation. More information can be found in the Communication by P. Yin et al. on page 14131 ff. [ABSTRACT FROM AUTHOR]

The structurally and dynamically perturbed hydration shells that surround proteins and biomolecules have a substantial influence upon their function and stability. This makes the extent and degree of water perturbation of practical interest for general biological study and industrial formulation. We present an experimental description of the dynamical perturbation of hydration water around green fluorescent protein in solution. Less than two shells (~5.5 Å) were perturbed, with dynamics a factor of 2-10 times slower than bulk water, depending on their distance from the protein surface and the probe length of the measurement. This dependence on probe length demonstrates that hydration water undergoes subdiffusive motions (τ ∝ q-2.5 for the first hydration shell, τ ∝ q-2.3 for perturbed water in the second shell), an important difference with neat water, which demonstrates diffusive behavior (τ ∝ q-2). These results help clarify the seemingly conflicting range of values reported for hydration water retardation as a logical consequence of the different length scales probed by the analytical techniques used. [ABSTRACT FROM AUTHOR]

This work addresses the detailed molecular dynamic behavior of miscible blends of Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) and their pure counterparts by quasi-elastic neutron scattering measurements (QENS). The study provides the measure of relaxation processes on pico-to-nanosecond time scales. A single relaxation process was observed in pure P3HT and PCBM while two relaxation processes, one fast and one slow, were observed in the blends. The fast process was attributed to the dynamics of P3HT while the slow process was correlated to the dynamics of PCBM. The results show that the relaxation process is a balance between two opposing effects: increased mobility due to thermal activation of P3HT molecules and decrease mobility due to the presence of PCBM which is correlated to the percent crystallinity of P3HT and local packing density of PCBM in the amorphous phase. The threshold for the domination of the thermally activated relaxation is between 5 and 9 vol.% of PCBM loading. Two distinct spatial dependences of the relaxation processes, in which the crossover length scale depends neither on temperature nor composition, were observed for all the samples. They were attributed to the collective motions of the hexyl side chains and the rotational motions of the C–C single bonds of the side chains. These results provide an understanding of the effects of PCBM loading and temperature on the dynamics of the polymer-fullerene blends which provides a tool to optimize the efficiency of charge carrier and exciton transport within the organic photovoltaic (OPV) active layer to improve the high performance of organic solar cells. [ABSTRACT FROM AUTHOR]

Room temperature ionic liquids (RTILs) have shown great potential in a wide range of applications, especially as novel electrolytes for energy generation. Understanding microscopic dynamics under variable environmental conditions provides critical knowledge of the microscopic interactions in RTILs, which are closely linked to their functionality. Here, we investigate a response of a RTIL, EmimTFSI, to application of a high pressure, up to 1.0 GPa, using quasi-elastic neutron scattering, Raman and X-ray scattering. The ionic liquid transitions from a liquid to a solid state at above ~0.5 GPa and returns to its liquid state following full decompression. However, following such pressure application, the resulting liquid no longer possesses either cations, or anions, as individual entities, as evident from quasi-elastic scattering and Raman scattering results, respectively. We suggest that a possible cause for this behavior could be dimerization of ions, which needs to be considered when designing RTILs for moderate high-pressure applications. [ABSTRACT FROM AUTHOR]

Water is widely assumed to be essential for protein dynamics and function. In particular, the well-documented "dynamical" transition at ~200 K, at which the protein changes from a rigid, nonfunctional form to a flexible, functional state, as detected in hydrogenated protein by incoherent neutron scattering, requires hydration. Here, we report on coherent neutron scattering experiments on perdeuterated proteins and reveal that a transition occurs in dry proteins at the same temperature resulting primarily from the collective heavy-atom motions. The dynamical transition discovered is intrinsic to the energy landscape of dry proteins. [ABSTRACT FROM AUTHOR]