Polymerized ionic liquids (PolyILs) are promising candidates for a broad range of technologies. However, the relatively low conductivity of PolyILs at room temperature has strongly limited their applications. In this work, we provide new insights into the roles of various microscopic parameters controlling ion transport in these polymers, which are crucial for their rational design and practical applications. Using broadband dielectric spectroscopy and neutron and light scattering techniques, we found a clear connection between the activation energy for conductivity, fast dynamics, and high-frequency shear modulus in PolyILs at their glass transition temperature (Tg). In particular, our analysis reveals a correlation between conductivity and the amplitude of fast picosecond fluctuations at Tg, suggesting the possible involvement of fast dynamics in lowering the energy barrier for ion conductivity. We also demonstrate that both the activation energy for ion transport and the amplitude of the fast fluctuations depend on the high-frequency shear moduli of PolyILs, thus identifying a practically important parameter for tuning conductivity. The parameters recognized in this work and their connection to the ionic conductivity of PolyILs set the stage for a deeper understanding of the mechanism of ion transport in PolyILs in the glassy state.

Carbon-based dots have been attracting much attention as potentially superior alternatives to more conventional semiconductor (e.g. cadmium-based) nanoparticles, due to their fascinating optical properties, chemical and photochemical stability, a unique environment-friendliness, and the versatility of fabrication routes. So far, different commercial materials and organic compounds were considered as carbon precursors for the syntheses but in many cases there are issues with their homogeneity or the fabrication that may require high-temperature conditions. We report on a simple low-cost procedure to produce hydrophilic and hydrophobic fractions of non-conjugated carbon-rich polymer dots (PDs) with the average diameter of 2-4 nm (hydrophilic PDs) and ca. 6 nm (hydrophobic PDs), involving acetone as carbon precursor. The as-obtained PDs reveal the greenish-blue photoluminescence (PL) that is characterized by high PL quantum yields (∼5-7%) and complex kinetics of the PL decays with the average lifetimes estimated to be 3.5 ns. Such luminescent acetone-based PDs may have potential in several application fields, including sensing and bioimaging.

We report a combined experimental and theoretical lattice dynamics study of the Ruddlesden–Popper layered compound Sr₂TiO₄. From inelastic neutron scattering experiments, we derive the generalized phonon density of states of Sr₂TiO₄. We also report its heat capacity, thermal expansion, and thermodynamic Grüneisen parameters using the calculated bulk modulus and find a large value of about 2. Using Raman scattering experiments under pressure, we discuss a potential structural distortion of the tetragonal structure above 11 GPa, which could be due to nonhydrostatic compression. The mode Grüneisen parameters of the four Raman-active modes are determined and shown to be in reasonable agreement with those obtained by density functional perturbation theory (DFPT) calculations. The temperature behavior of the Raman-active modes was studied, allowing us to determine the implicit volume and explicit anharmonic contributions. Above 400 K, the implicit volume contribution dominates the temperature-induced variation of the four Raman-active modes, whereas, below this temperature, the explicit anharmonic contribution is the dominant contributor to the highest energy mode. Our results underline the importance of anharmonicity in vibration-related properties of Sr₂TiO₄.

Nematic twist-bend phases (N-TB) are new types of nematic liquid crystalline phases with attractive properties for future electro-optic applications. However, most of these states are monotropic or are stable only in a narrow high temperature range. They are often destabilized under moderate cooling, and only a few single compounds have shown to give room temperature N-TB phases. Mixtures of twist-bend nematic liquid crystals with simple nematogens have shown to strongly lower the nematic to N-TB phase transition temperature. Here, we examined the behaviour of new types of mixtures with the dimeric liquid crystal [4 ',4 '-(heptane-1,7-diyl)bis(([1 ',1 ''-biphenyl]4 ''-carbo-nitrile))] (CB7CB). This now well-known twist-bend nematic liquid crystal presents a nematic twist-bend phase below T approximate to 104 degrees C. Mixtures with other monomeric alkyl or alkoxy -biphenylcarbonitriles liquid crystals that display a smectic A (SmA) phase also strongly reduce this temperature. The most interesting smectogen is 4 '-Octyl-4-biphenylcarbonitrile (8CB), for which a long-term metastable N-TB phase is found at room and lower temperatures. This paper presents the complete phase diagram of the corresponding binary system and a detailed investigation of its thermal, optical, dielectric, and elastic properties.

In response to the fresh water scarcity, Tunisia is utilizing more and more membrane desalination of unconventional resources, including brackish waters and seawater. The widespread reserves of groundwaters and their low salinity make this resource of special interest. Two predominant ionic compositions have been identified depending on their relative proportion of sulfate to chloride ions. The question arising for the decision-makers concerns the choice of membrane technology and, therefore, of membrane. Two nanofiltration (NF) membranes (NF270 and NF90) and a reverse osmosis (RO) one (BW30) were tested in a desalination study of synthetic feeds reproducing the ionic composition of three representative groundwaters. Sulfate/chloride ratio appears to be the key factor for the membrane choice to obtain good quality drinking water meeting the Tunisian standards. Moreover, validation of two prediction tools was investigated: ROSA, software provided by the membrane manufacturer and Nanoflux ® , software specifically designed for NF. The experimental NF results are well fitted by the Nanoflux ® simulations. We concluded that ROSA cannot generally provide good NF predictions because it does not take into account the electric interactions between membrane and feed.

Nonlinear nanophotonics leverages engineered nanostructures to funnel light into small volumes and intensify nonlinear optical processes with spectral and spatial control. Owing to its intrinsically large and electrically tunable nonlinear optical response, graphene is an especially promising nanomaterial for nonlinear optoelectronic applications. Here we report on exceptionally strong optical nonlinearities in graphene–insulator–metal heterostructures, which demonstrate an enhancement by three orders of magnitude in the third-harmonic signal compared with that of bare graphene. Furthermore, by increasing the graphene Fermi energy through an external gate voltage, we find that graphene plasmons mediate the optical nonlinearity and modify the third-harmonic signal. Our findings show that graphene–insulator–metal is a promising heterostructure for optically controlled and electrically tunable nano-optoelectronic components.