Characterization Study of CO2, CH4, and CO2/CH4 Hydroquinone Clathrates Formed by Gas–Solid Reaction

Hydroquinone (HQ) is known to form organic clathrates with some gaseous species such as CO2 and CH4. This work presents spectroscopic data, surface and internal morphologies, gas storage capacities, guest release temperatures, and structural transition temperatures for HQ clathrates obtained from pure CO2, pure CH4, and an equimolar CO2/CH4 mixture. All analyses are performed on clathrates formed by direct gas–solid reaction after 1 month’s reaction at ambient temperature conditions and under a pressure of 3.0 MPa. A collection of spectroscopic data (Raman, FT-IR, and 13C NMR) is presented, and the results confirm total conversion of the native HQ (α-HQ) into HQ clathrates (β-HQ) at the end of the reaction. Optical microscopy and SEM analyses reveal morphology changes after the enclathration reaction, such as the presence of surface asperities. Gas porosimetry measurements show that HQ clathrates and native HQ are neither micro- nor mesoporous materials. However, as highlighted by TEM analyses and X-ray tomography, α- and β-HQ contain unsuspected macroscopic voids and channels, which create a macroporosity inside the crystals that decreases due to the enclathration reaction. TGA and in situ Raman spectroscopy give the guest release temperatures as well as the structural transition temperatures from β-HQ to α-HQ. The gas storage capacity of the clathrates is also quantified by means of different types of gravimetric analyses (mass balance and TGA). After having been formed under pressure, the characterized clathrates exhibit exceptional metastability: the gases remain in the clathrate structure at ambient conditions over time scales of more than 1 month. Consequently, HQ gas clathrates display very interesting properties for gas storage and sequestration applications

Janus organic semiconductor nanoparticles prepared by simple nanoprecipitation

Nanoparticles (NPs) of donor–acceptor organic semiconductors are produced by a one-step nanoprecipitation with Janus morphology. Electron donor P3HT was blended with electron acceptor PC61BM in tetrahydrofuran and then precipitated in water, first with surfactant and second without surfactant. Cryogenic transmission electron microscopy reveals an internal Janus structure at high magnification, for NPs which have, in the past, been reported to have a molecularly intermixed morphology. Synchrotron-based scanning transmission X-ray microscopy confirmed the segregation of the organic semiconductors and photoluminescence experiments showed an efficient electron transfer from P3HT to PC61BM. Organic field effect transistors were fabricated with these Janus NPs and showed that the positive charges can be efficiently transported through thin films. This behavior proves that the NPs possess an electron-accepting face (the PC61BM face) able to transport electrons and a hole-accepting face (the P3HT face) for the conduction of holes. Finally, the deposition of silver via the photoreduction of a silver salt (AgNO3(aq)) was demonstrated, as a proof of concept. These experiments show the potential of the Janus NPs for photovoltaics but also photocatalytic reactions in which reduction and oxidation reactions can occur at opposite sides of the nanoreactor (the individual Janus NPs).E2SEncres aqueuses colloïdales de semi-conducteurs organiques pour le photovoltaïqu

Synthesis of organic and bioorganic nanoparticles: An overview of the preparation methods

DOI: 10.1007/978-1-4471-4213-3International audienceSince the emergence of Nanotechnology in the past decades, the development and design of organic and bioorganic nanomaterials has become an important field of research. Such materials find many applications in a wide range of domains such as electronic, photonic, or biotechnology, which contribute to impact our society and our way of life. The improvement of properties and the discovery of new functionalities are key goals that cannot be obtained without a well controlled and a better understanding of the preparation methods which constitute the starting point of the design of a specific organic material. In this context, this chapter gives a general but non-exhaustive overview of the methods of preparation of organic and bioorganic nanoparticles. Some general definitions about organic nanoparticles and description of organic compounds are given before describing the most common methods used divided into two families, the two-step and one-step procedures. The major part of the two-step procedures is based on an emulsification step followed by generation of nanoparticles through different mechanisms such as precipitation, gelation, or polymerization. The one-step procedures are founded on generation of nanoparticles through different techniques such as nanoprecipitation, desolvation, or drying processes without preliminary emulsification step. For each method, the description is supported by several examples and focused on the explanation of the general mechanisms and of the major key parameters involved in the control of the nanoparticles formation. In addition, since emergence and improvement of syntheses are often associated to development of experimental setups, technological aspects are also mentioned. © Springer-Verlag London 2013

Développement de nouvelles méthodes pour l'élaboration d'émulsions multiples eau/huile/eau

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