Temperature is one of the basic parameters often required to characterize a system. A great demand has arisen for localmeasurements, especially in liquids or complex biological environments. Various approaches have been proposed to study thetemperature at the nano-scale level. Some of them are based on the spectroscopic properties of carbon nanotubes (CNT) usedas sensors.
Raman spectroscopy is indeed a powerful technique to identify single-walled carbon nanotubes (SWNT) and to study theirstructure, defects and electronic properties through the measurement of specific Raman signatures (RBM, D, G and 2D bands).On the other hand, individual SWNT or small bundles emit light in the near infrared and the photoluminescence (PL) spectra isvery sensitive to the quality of the dispersion and the dielectric environment of the nanotubes. In particular, when SWNT aredispersed in aqueous solutions, the PL energies are sensitive to the nature of the surfactants or polymers, to theirconcentration, and to the way they adsorb on/wrap around the nanotubes.
In this work we show that the PL/Raman spectra of SWNT dispersed with sodium dodecyl sulfate (SDS) is very sensitive to thetemperature (figure 1) in a large range of SDS concentrations. We discuss the influence of the chiral angle of the SWNT onthese PL changes, and the origin of the changes in terms of SDS reorganization at the surface of the nanotubes. Similarchanges are obtained with increasing laser power (figure 2), showing the local heating of the nanotubes. These results pavethe way for the development of SWNT-based nano-thermometers.

Polymers with dynamic (transient) bonds, often called associating polymers, have been attracting significant attention in recent years due to their unique viscoelastic properties, self-healing ability, and recyclability. Nevertheless, understanding the mechanisms and the factors controlling their macroscopic properties remains limited due to the higher complexity introduced by the dynamic bonds. In this study, small-angle X-ray scattering (SAXS), broadband dielectric spectroscopy (BDS), and rheology were applied to unravel the structure and dynamics of telechelic associating polymers with different molecular weights. SAXS measurements revealed phase separation of the functional end groups with an average cluster size of ∼2–3 nm and the distance between clusters controlled by the chain length. Borrowing the interfacial layer model analysis of BDS data from the polymer nanocomposite field, we demonstrated the presence of an interfacial polymer layer with a thickness of ∼0.7–0.9 nm surrounding these clusters. Rheological measurements showed quantitatively that the presence of the interfacial layer significantly alters the viscoelastic behavior of these materials, indicating the crucial role of the interfacial layer in defining the macroscopic mechanical properties of the studied telechelic materials. The presented results emphasize that phase separation of the functional groups in associating polymers leads to very significant changes of the viscoelastic properties, opening a promising avenue in the design of novel functional materials.

We have elaborated a new preparation method of ternary AgInS2 and alloyed quaternary AgInS2-ZnS nanocrystals which consisted of two consecutive injections of sulfur (S dissolved in oleylamine, OLA) and then silver (AgNO3 or Ag2CO3 dissolved in dichlorobenzene, DCB) precursors to a mixture of indium(III) chloride, zinc stearate and 1-dodecanethiol (DDT) dissolved in 1-octadecene (ODE). In these conditions nucleation of cubic In2S3 seeds took place followed by the growth of orthorhombic AgInS2 or alloyed AgInS2-ZnS cubic phases to yield a heterodimer type of nanocrystals. In both types of nanocrystals clearly separated photoluminescence peaks could be observed, confirming their heterogenic nature. The first one at 430 nm originated from the luminescence of the In2S3 phase. The second one was ascribed to the presence of ternary Ag-In-S or quaternary Ag-In-Zn-S phases and its position, within the spectroscopic range from 515 nm to 710 nm, strongly depended on the nanocrystals composition. The registered two-dimensional excitation-emission topographical maps clearly indicated that the observed emissions in two different spectral regions were related to the excitations in the same spectral range (300-400 nm), however their photoluminescence mechanisms were distinctly different. The photoluminescence lifetime of 3 ns measured for the emission at shorter wavelengths was typical of the simple mechanism of excitons radiative recombination in the In2S3 phase. Significantly longer lifetime of the longer wavelengths emission (26 s) seemed to clearly indicate that in this case the photoluminescence mechanism was more complex, involving exciton trap states whose positions depended on the composition of the ternary (or quaternary) phase.

Downsizing electronic and electric equipment requires the optimization of electric field distributions in order to avoid localized dielectric breakdown (also called partial discharges). This paper presents a novel dielectric composite material aimed at grading electrical local surface stress. This functional material has a conductivity which increases by several orders with the applied electric field giving the ability to distribute the field by itself. It is prepared for the first time by dispersing graphite nanoplatelets in a polymer and may be used as a resistive or capacitive field grading material in electronic and electrical applications. Mechanisms at the origin of the nonlinear behavior are discussed.

We clarify some analytical expressions existing in the literature, • Within the correct formulae we conclude that there is no need for an ad hoc improvement on the opposite to the title paper, • We highlight the symmetry properties of the function to be integrated in order to agree with the usual assumptions made to derive the Kramers-Kronig relations, • The analytical formula we provide may be used to increase the accuracy of the "Poor Man's Kramers-Kronig analysis" method and the "Kramers-Kronig constrained variational analysis" method.

We report a microscopic model of the phonon-adsorption correlations in flexible metal−organic framework materials. We analyze the mechanism of the gate opening deformation using the notion of coupled phonon- and adsorption-induced structural transformation. Using the ZIF-8 structure as an example, we perform an analysis of transformation-related, low-frequency phonon modes of the framework.On the basis of structure-related quantities such as pore limiting diameter, void fraction, and adsorption uptake, we determine the conditions which lead to the gate opening transformation in ZIF-8. Energetic landscape of the deformation process is analyzed using grand thermodynamic potential of adsorption. We generalize our conclusions to other flexible ZIF structures with the same topology.

Pesticide sensing is an important object of study due to its increasing use worldwide. Herein, we report a SERS study of 4-nitrophenol (PNP), which is product of neutralization processes of various pesticides such as Paraoxon, and can be used as a target molecule for monitoring. PNP is also widely used in the chemical industry and due to its high toxicity is considered a concerning pollutant. The sensing was carried out with a reduced graphene oxide nanocomposite functionalized with cysteamine and Ag nanoparticles (rGOSHAg), and compared with raw reduced graphene oxide and a commercial SERS substrates (SERStrate (TM)). A mechanistic evaluation was also carried out, focused in the degradation of PNP caused by the different exciting laser lines, evidencing the PNP dimerization in substrates containing Ag NPs (under 532 nm laser), which has important outcomes for sensing purposes. The nanocomposite rGOSHAg presented the highest sensitivity towards PNP, detecting concentrations as low as 10(-6) mol L-1 and with a high potential for field applications and real-time measurements of molecules commonly present in pesticides and industrial contaminants.