Phase properties of gases adsorbed in small nanopores are mainly determined by the pore size and shape as well as the structural heterogeneity of the adsorbate. Here we analyze the evolution of the melting mechanism that occurs in pores <3 nm in size. Melting in slit-shaped graphene pores is compared with melting in SURMOF channel pores with square cross-sections. We show how the melting transformation is related to the adsorption mechanism. We use a graphical representation of the evolution of molecular density as a function of temperature in the nanopores.

Ultralight mechanical resonators based on low dimensional materials are well suited as exceptional transducers of minuscule forces or mass changes. However, the low dimensionality also provides a challenge to minimize resistive losses and heating. Here, we report on a novel approach that aims to combine different two-dimensional (2D) materials to tackle this challenge. We fabricated a heterostructure mechanical resonator consisting of few layers of niobium diselenide (NbSe2) encapsulated by two graphene sheets. The hybrid membrane shows high quality factors up to 245,000 at low temperatures, comparable to the best few-layer graphene mechanical resonators. In contrast to few-layer graphene resonators, the device shows reduced electrical losses attributed to the lower resistivity of the NbSe2 layer. The peculiar low-temperature dependence of the intrinsic quality factor points to dissipation over two-level systems which in turn relax over the electronic system. Our high sensitivity readout is enabled by coupling the membrane to a superconducting cavity which allows for the integration of the hybrid mechanical resonator as a sensitive and low loss transducer in future quantum circuits.

A series of double hydrophilic block copolymers DHBCs has been synthesized by controlled radical polymerization (Figure 1). Poly(ethylene oxide)-b-poly(acrylic acid) PEO-b-PAA was prepared by ATRP in acetone. PEO-b-PAA and PEO-b-Poly(N-isopropyl acrylamide) PEO-b-PNIPAM were prepared by RAFT using a PEO-based dithiobenzoate macro-RAFT agent, in water and dioxane respectively. Poly(poly(ethylene glycol) methyl ether acrylate)-b-PAA PmPEGA-b-PAA was prepared by RAFT in water using a trithiocarbonate RAFT agent. Poly(acrylamide)-b-PAA PAM-b-PAA and PAM-b-poly(3-acrylamidopropyl)trimethylammonium chloride) PAM-b-PAPTAC were prepared by RAFT/MADIX using xanthate as control agent, in water/ethanol for the PAM block and directly in water for the second block. The block copolymers have been characterized by SEC, pH titration, conductimetry, and capillary electrophoresis (CE).The reversible formation of micelles by variation of temperature in the case of PEO-b-PNIPAM, or by the mixing of polyelectrolyte DHBCs with a polyelectrolyte of opposite charge in the right range of pH (e.g. anionic PEO-b-PAA associated with cationic oligochitosan) has been studied. The micelles have been characterized by various scattering techniques and CE.Such stimuli-responsive (T, pH, ionic strength) micellar systems have been involved as structuring agents in the synthesis of nanostructured mesoporous silica by sol-gel process. A relationship between the composition of the DHBCs, the composition of the micelles, the experimental conditions of micelle formation and the final mesostructure of the silica materials is foreseen. This strategy has been applied to the preparation of drug-loaded silica for biomedical applications.

An organogelator based on a N,N′-substituted H-bonding perylenebisimide (PBI-C10) self-assembles to form either a green J-type (form I) or a red H-type (form II) aggregate structure. The molecular packing of both polymorphs was determined from a combination of Transmission Electron Microscopy (TEM) (low dose electron diffraction and high resolution), Grazing incidence X-ray diffraction and polarized infrared spectroscopy. To that aim, highly oriented films have been prepared by mechanical rubbing at controlled film temperature and DFT calculations were performed to identify representative vibrational IR bands and their associated polarizations. H-Bonding between amides generates either a rectangular columnar phase (form I) in the dried gel or a hexagonal packing of supramolecular 21/1 helices with a long period of 97 Å (form II) in annealed thin films. In aligned films of form I, polarized FTIR spectroscopy helps determine the orientation of both intermolecular H-bonds and the PBI core with respect to the substrate. In form II, PBI-C10 molecules assemble into pairs to form off-centered 21/1 helices whose helical axis is made of strongly H-bonded amides. TEM investigations show that three 21/1 helices are packed in a frustrated trigonal structure formed by H-bonding. The Form I → Form II transformation implies a redistribution of a single population of strong intra-columnar H-bonds between amides in form I to a mixture of strong and weak H-bonds in the supramolecular helices, the strong H-bonds forming the spine of the helices.

Double-walled carbon nanotubes (DWNT) are made of two concentric and weakly van der Waals coupled single-walled carbon nanotubes (SWNT). DWNTs are the simplest systems for studying the mechanical and electronic interactions between concentric carbon layers.In this paper we review recent results concerning the intrinsic features of phonons of DWNTs obtained from Raman experiments performed on index-identified DWNTs. The effect of the interlayer distance on the strength of the mechanical and electronic coupling between the layers, and thus on the frequencies of the Raman-active modes, namely the radial breathinglikemodes (RBLMs) and G-modes, are evidenced and discussed.

We present experimental measurements of the features of G band in individual index-identified free-standing double-walled carbon nanotubes. We examine Raman spectra of different electronic configurations of DWNTs, namely: SC@SC, SC@M, M@SC, M@M, and clearly establish that, as in SWNTs, the profile of LO G-mode of each layer is broad (narrow) when the layer is metallic (semiconducting). The dependence of G-modes on thediameter and inter-layer distance in several SC@SC, SC@M, M@SC, M@M index-identified DWNTs is reported. We find, that, independently of the metallic or semiconducting nature of the layers, the frequencies of LO and TO G-mode of the inner and outer layers shift significantly with respect to the frequencies of the same modes in the constituent SWNTs.