The use of electrochemical template synthesis for the formation of electrochromic composite nickel hydroxide/PVA films with poor inside stress, effective adhesion to substrate and high optical and electrochemical properties is proposed.Influence of the deposition current density and of the amount of PVA on the structure, surface morphology and transparency of the electrodeposit films is investigated. It is thus concluded that the optimal current density is 0.625 mA/cm2 for the pure Ni(OH)2 film whereas the optimal concentration of PVA is 5% weight is. Overall, the electroplated Ni(OH)2/PVA films exhibit an X-ray amorphous structure, due to the Ni(OH)2 particle growth in the nano-size cells of the 3D network of the PVA template. Surface morphology of films, deposited with the template synthesis, is investigated by SEM. The film electrodepositing rate by template synthesis was estimated around the 3.87 μm/h at the current density of the 0.625 mA/cm2. Template incorporating into the nickel hydroxide film has been proved by EDX analysis. Electrochemical and electrochromic properties of films, deposited by electrochemical template synthesis and dried at 20 °C and 90 °C, have been investigated. It was shown that both types of films have high properties (charge/discharge and colorization-bleaching processes). But films, dried at 20 °C, has the best electrochemical properties and larger colorization depth, however the colorization/bleaching process has larger reversibility for the sample dried at 90 °C

The rise of efficient extraction techniques triggered a renewal of interest in semiconducting carbon nanotubes (s-SWNT) research. It represents a great interest for optoelectronics, with outstanding properties in field-effect transistor, and s-SWNT ability to efficiently emit light in the near-IR range. In particular, polyfluorene (PFO) wrapped s‑SWNT (s-SWNT@PFO) display strong photoluminescence, and could be coupled with photonic devices such as microring resonators [1,2] to control photoluminescence linewidth and enhance photoluminescence intensity.The main challenge for using s-SWNT@PFO in optoelectronics lies in the difficulty to establish good electrical contact with a PFO embedded carbon nanotube. We propose to investigate these issues by tuning the amount of PFO wrapping around s-SWNT. A low pressure annealing process is used to selectively remove PFO around s‑SWNT without burning nanotubes themselves (Figure). The resulting s-SWNT@PFO networks are then probed by AFM, Raman spectroscopy, absorption, photoluminescence and electrical experiments.

Nanophotonics is an emerging field where researchers look for potential application of carbon nanotubes (SWNT) in the framework of silicon photonics technology, due to SWNT ability to emit, modulate and detect light in the wavelength range of silicon transparency.In this field of nanotube photonics, a first milestone was to couple light emission from SWNT into silicon waveguides [1]. Current researches focus on coupling SWNT with optical cavities, either for enhancing nanotube photoluminescence (PL) or nonlinear optical phenomena at the nanoscale, using microdisk resonators, or photonic crystal cavities. However, these kinds of cavities could not be easily coupled to silicon waveguides, hindering subsequent integration into more complex photonic devices.Building up on our previous work [2], we propose to couple SWNT PL with silicon microring resonators in a fully integrated configuration, with an acess waveguide [3]. PL coupled to microring modes could be collected from the access waveguide, with efficient rejection on non-resonant photons. Emission quality factor up to 8000 were observed. This design allow for collinear excitation of SWNT through the access waveguide, leading to efficient excitation and collection of SWNT PL at different wavelengths. The requirement for out-of-the-plane SWNT excitation is lifted, underlining the pertinence of this approach for realistic carbon nanotube based photonic devices.References1. E. Gaufrès, N. Izard, A. Noury, X. Le Roux, G. Rasigade, A. Beck and L. Vivien, ACS Nano 6, 3813 (2012)2. A. Noury, X. Le Roux, L Vivien and N. Izard, Nanotechnology 25, 215201 (2014)3. A. Noury, X. Le Roux, L. Vivien and N. Izard, Nanotechnology 26, 345201 (2015)

The control of structuring and morphology in hybrid solids is a key parameter for the design of functional materials. In particular, it has been shown that structure and morphology could be tuned through sol gel synthesis conditions in bridged silsesquioxanes (BS). As a matter of fact, during sol-gel process, the competition between self-assembing through non covalent interactions between the organic sub-structures and condensation of the inorganic siliceous sub-structure can lead to the formation of crystalline compounds or amorphous materials.In order to go further with the understanding of the control of the nanostructuring in bridged silsequioxane, we designed the organic moieties of the precursors with either 2 symetrical through hydrogen bond and the strength of these hydrogen bonds is studied through vibrational spectroscopies in-situ at low temperature or at high pressure. The results are analyzed and discussed in terms of H bond strength and geometric factors.In the second part of this talk, we will focus on the influence of the central subunit lying between the two urea/thiourea groups_either a long flexible alkyl chain or rigid phenyl group_ on the self-assembling properties through H bonds.

Bridged silsesquioxane nanomaterials exhibit original mechanical properties thanks to the association of non-covalent and covalent interactions. Thanks to in situ high pressure spectroscopic studies, achieved in diamond anvil cells, the mechanical behavior of these materials was followed as a function of pressure. Vibrational studies coupled to ab-initio simulations show that mechanical constrains are absorbed by the modulation of H bond interactions. We thus show that the rigidity yielded by the inorganic polymerization is counterbalanced by the presence of the intermolecular H bond network. In a large range of pressures, these hybrid materials have a reversible behavior, and thus behave as molecular springs. In a second time, we demonstrate that the pressure behavior of these molecular spring is sensitive to the conformation of H bonds (cyclic versus linear) and to the constraints imposed the covalent inorganic network.

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.