Carbon nanotubes (CNTs) possess extraordinary mechanical, thermal, and electrical properties due to their atomically perfect structure and sp2-hybridization. Recently, Single-wall CNTs (SWCNTs) have become an interesting host for the nanoscale confinement of fluids, with a wealth of surprising phenomena appearing: spontaneous filling, frictionless mass transport, unusual phase diagram, etc[1]. Most of these phenomena are still under debate and call for experimental confirmation. But the field is struggling with finding experimental approaches sensitive enough to carry out measurements at the level of individual nanotubes. SWCNT field effect transistors (SWCNT-FETs) showed that the electronic properties of SWCNTs are sensitive to their diameter, defects, doping, adsorbates, and environment [2], [3].In this contribution, we demonstrate that individual carbon nanotube field effect transistors (CNTFET) are excellent tools for this aim, for the first time allowing to precisely identify water confined inside the nanotube. By studying the electrical performances of several unopened and opened CNTFETs submitted to various atmosphere and temperature treatments, i.e. dry air, humidity, secondary vacuum, and current annealing, we show that it is possible to distinguish water being outside and inside the nanotube, just outside, or the nanotube free from water. We thus observed that for opened SWCNT both secondary vacuum and current annealing move threshold gate voltage towards more negative values, while for closed SWCNT secondary vacuum had no effect compared to current annealing. To sum up, the current annealing treatment is essential to distinguish water adsorbed outside from water confined inside. We show that this behavior is universal, as all devices' metallicities behave similarly, provided that the surface of the nanotube is pre-cleaned by current annealing. We will also discuss the mechanisms behind the coupling of electronic transport and the presence of water.Our results open up the possibility to use CNTFET for instance reliable, selective, and sensitive chemical and biological sensors, and also, to resolve the long-standing questions in the nanofluidic community about the behavior of water under nanoscale confinement.Reference:[1] T. A. Pascal, W. A. Goddard, and Y. Jung, “Entropy and the driving force for the filling of carbon nanotubes with water,” Proc. Natl. Acad. Sci., vol. 108, no. 29, pp. 11794–11798, 2011, doi: 10.1073/pnas.1108073108.[2] D. Cao et al., “Electronic sensitivity of carbon nanotubes to internal water wetting,” ACS Nano, vol. 5, no. 4, pp. 3113–3119, 2011, DOI: 10.1021/nn200251z.[3] I. Heller, A. M. Janssens, J. Männik, E. D. Minot, S. G. Lemay, and C. Dekker, “Identifying the mechanism of biosensing with carbon nanotube transistors,” Nano Lett., vol. 8, no. 2, pp. 591–595, 2008, DOI: 10.1021/nl072996i.

The synthesis of multifunctional poly(amidoamine)(PAMAM)-based dendrimers containing a cleavable disulfide linkerwithin each armof the dendrimer, together with condensable triethoxysilyl groups on the periphery of the dendrimer, isdescribed. The dendrimers were mixed with bis(triethoxysilyl)benzene and subsequently transformed into silsesquioxanegels or periodic mesoporous organosilicas (PMOs) to generate materials with dendrimers covalently embedded within theinterior of the silsesquioxane networks. Subsequent treatment of the gels with dithiothreitol enabled the core of thedendrimers to be selectively cleaved at the disulfidesite, thus generating thiol functions localised within the pores.The effect of different dendrimer generations on the reactivity of the pendant thiol functions was probed by impregnationwith gold salts, which were reduced to obtain gold nanoparticleswithin the pore networks of the gels and PMOs. The gelsyielded polydisperse gold nanoparticles (2 to 70 nm) with dimensions modulated by the generation of thedendrimer,together with well-defined gold/thiolate clusters with Au...S distances of 2.3 Å. Suchclusters were also observed in the PMOsystem, together with monodispersed gold nanoparticles with diameters comparable to that of the organised pores in thePMO. The role of surface functionalisation in controlling the formation of gold clusters and/or nanoparticles is discusse

Nanoparticles made of a substance derived from wood, lignin, are gaining interest as a potential material for use in nanotechnology, including such biological applications as photodynamic antimicrobial chemotherapy (PACT) and photodynamic therapy (PDT), which involve the need for the nanoparticles to contain photosensitizers that absorb and emit in certain wavelength ranges. Among the possible approaches there is one relying on utilizing two-photon absorption in the near infrared region. In this work, we present the linear and non-linear photophysical properties of acetylated lignin nanoparticles which have been loaded with porphyrin, in particular, the femtosecond laser-induced emission which was measured for a single nanoparticle. We demonstrate that these nanoparticles can be excited in the so-called first (NIR-I) and second (NIR-II) optical window in the near-infrared (650–950 nm and 1000–1350 nm, respectively). Because their emission also occurs in the NIR, this presents an advantage for the monitoring of the use of these porphyrin-particle hybrids within PDT and PACT applications.

This work focuses on the temperature-dependent structural and rheological characterization of polystyrene-b-poly(n-butyl acrylate)-b-polystyrene triblock copolymers (PS-b-PnBA-b-PS) in the melt and, in particular, on their ability to show a lower disorder-to-order temperature (LDOT). To this aim, copolymers of varying block lengths, but keeping the PnBA block as a major component, were synthesized. Smallangle x-ray scattering revealed that the copolymers with short PS blocks (∼10 kg/mol) approach an LDOT but do not cross it. At room temperature, these copolymers exhibit higher moduli compared to a PnBA homopolymer due to the reinforcing effect of the PS but are flowing at temperatures above the glass transition of the PS. Increasing the PS and PnBA block length, to keep the same PS fraction, induces more profound changes in the structural and viscoelastic behaviors. Such a copolymer crosses the LDOT, leading to a microphase-separated and ordered state at high temperature. Contrary to the copolymers with short PS blocks, the flow regime was not reached, even at temperatures well above the glass transition of the PS. Instead, a low-frequency plateau was observed in rheology, showing the increased lifetime of the microphase-separated PS domains. ABA triblock copolymers exhibiting an LDOT behavior could, thus, be of interest for the design of thermoplastic elastomers or pressure-sensitive adhesives that can resist the flow at high temperatures

Polarized fluorescence emission of nanoscale emitters has been extensively studied for applications such as bioimaging, display, and optical communication. Extending the polarization properties in large assemblies of compact emitters is, however, challenging because of self-aggregation processes, which can induce depolarization effects, quenching, and cancellations of molecular dipoles. Here we use a-sexithiophene (6T) molecules confined inside boron nitride nanotubes (6T@BNNTs) to induce fluorescence anisotropy in a transparent host. The experiments first indicate that individual 6T@BNNTs exhibit a high polarization extinction ratio, up to 700, at room temperature. Using aberration- corrected HRTEM, we show that the fluorescence anisotropy is consistent with a general alignment of encapsulated 6T molecules along the nanotube axis. The molecular alignment is weakly influenced by the nanotube diameter, a phenomenon ascribed to stronger molecule-to-sidewall interactions compared to intermolecular interactions. By stretching a flexible thin film made of transparent polymers mixed with 6T@BNNTs, we induce a macroscopic fluorescence anisotropy within the film. This work demonstrates that the dyes@BNNT system can be used as an easy-to-handle platform to induce fluorescence anisotropy in photonic materials.