CO2–Hydroquinone Clathrate: Synthesis, Purification, Characterization and Crystal Structure

Organic clathrate compounds, particularly those formed between hydroquinone (HQ) and gases, are supramolecular entities recently highlighted as promising alternatives for applications such as gas storage and separation processes. This study provides new insights into CO2–HQ clathrate, which is a key structure in some of the proposed future applications of these compounds. We present a novel synthesis and purification of CO2–HQ clathrate monocrystals. Clathrate crystals obtained from a single synthesis and native HQ are characterized and compared using Raman/Fourier transform infrared/NMR spectroscopies, optical microscopy, and thermogravimetric analysis coupled to mass spectrometry. The molecular structure of the clathrate has been resolved by X-ray diffraction analysis, and detailed crystallographic information is presented for the first time

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

Creating innovative composite materials to enhance the kinetics of CO 2 capture by hydroquinone clathrates

This study addresses both the preparation of a reactive medium composed of porous particles impregnated with hydroquinone (HQ), an organic compound capable of forming gas clathrates, and an evaluation of the kinetic performance of these composite materials for CO2 capture. Two types of porous silica particles of different sizes and pore diameters were tested. The porous particles were impregnated with HQ by a dry impregnation (DI) method in a fluidized bed, and by a wet impregnation (WI) method. The impregnation effectiveness of the two methods is discussed, and the reactivity of the composite materials formed in terms of CO2 capture and storage capacity is studied experimentally. The experimental results showed that the HQ adheres well on the silica without any chemical modification of the deposit’s structure. We demonstrated that the impregnation technique plays a very important role in the kinetics of CO2 capture. A series of experiments performed using a magnetic suspension balance at 3.0 MPa and 323 K showed that the silica-based impregnated particles reversibly capture and store CO2, and that the CO2 capture kinetics are significantly enhanced compared to the results obtained with pure powdered HQ. Finally, we demonstrated that CO2 capture is faster with dry-impregnated particles

Study of sodium dodecyl sulfate - Poly(propylene oxide) methacrylate mixed micelles

cited By 23International audienceSodium dodecyl sulfate (SDS) - poly(propylene oxide) methacrylate (PPOMA) (of molecular weight Mw = 434 g·mol-1) mixtures have been studied using conductimetry, static light scattering, fluorescence spectroscopy, and 1H NMR. It has been shown that SDS and PPOMA form mixed micelles, and SDS and PPOMA aggregation numbers, Nag SDS and Nag PPOMA, have been determined. Total aggregation numbers of the micelles (Nag SDS + Nag PPOMA) and those of SDS decrease upon increasing the weight ratio R = PPOMA/SDS. Localization of PPOMA inside the mixed micelles is considered (i) using 1H NMR to localize the methacrylate function at the hydrophobic core - water interface and (ii) by studying the SDS - PPO micellar system (whose Mw = 400 g·mol-1). Both methods have indicated that the PPO chain of the macromonomer is localized at the SDS micelle surface. Models based on the theorical prediction of the critical micellar concentration of mixed micelles and structural model of swollen micelles are used to confirm the particular structure proposed for the SDS - PPOMA system, i.e., the micelle hydrophobic core is primarily composed of the C12 chains of the sodium dodecyl sulfate, the hydrophobic core - water interface is made up of the SDS polar heads as well as methacrylate functions of the PPOMA, the PPO chains of the macromonomer are adsorbed preferentially on the surface, i.e., on the polar heads of the SDS

Thermodynamic investigation of thermoresponsive xanthan-poly (N-isopropylacrylamide) hydrogels

cited By 10International audiencePolysaccharide-based hydrogels, such as xanthan maleate/poly(N-isopropylacrylamide) (PNIPAAm) interpenetrated polymer networks, are thermostimulable materials of interest for the controlled release of biologically active components due to conformation changes at the low critical-solution temperature (LCST) PNIPAAm phase transition. The phase transition of these interpenetrated polymer network hydrogels, where PNIPAAm is in a 'confined' environment, was examined by high resolution magic angle spinning nuclear magnetic resonance and differential scanning calorimetry. High resolution magic angle spinning nuclear magnetic resonance spectroscopy allows the accurate determination of LCST and an evaluation of the corresponding thermodynamic data. More particularly, the evolution of these data as a function of the composition of the hydrogel, and of the external parameters such as pH and ionic strength, was considered. LCST shows a minimal value with increasing xanthan content. Moreover, it was possible to calculate, as a function of temperature, the fraction of NIPAAm which remains uncollapsed. The data obtained for pure PNIPAAm hydrogels are in good agreement with recently published results. The phase transition of PNIPAAm in a diphasic hydrogel is broader when PNIPAAm is 'confined' within an interpenetrated polymer network than in a pure PNIPAAm crosslinked network. The widening of the transition with increasing xanthan content indicates a reduction of the PNIPAAm interchain aggregation in a network structure. © 2011 Society of Chemical Industry

Characterization of model luminescent PPV analogues with donating or withdrawing groups

cited By 9International audienceSeveral oligomers analogous to poly(p-phenylene vinylene) (PPV) were synthesised by the Wittig reaction, to be used as model compounds for the study of structure/properties relationship. They are based on benzene-1,4-bis(phenylene vinylene) (OPPV) substituted by electron-withdrawing (nitro) or electron-donating (methyl and dimethylamino) groups on the terminal rings of the molecule. Moreover, two other oligomers 2-hexadecyloxy-5-methoxybenzene-1,4-bis(phenylene vinylene) (1-16-OPPV) and 2-hexadecyloxy-5-methoxybenzene-1,4-bis(4-dimethylaminophenylene vinylene) (1-16-NC-OPPV) were prepared with alkoxy groups on the central ring of the molecule. After a complete structural characterization by FTIR, 1H and 13C NMR, particular emphasis was placed upon the investigation of their thermal stability by TGA and their optical properties in tetrahydrofuran (THF) solutions. Depending on the substituent and on its position in the molecule a different thermal behaviour was observed. Moreover, a red-shift from 10 to 50 nm was observed for the emission wavelength, with respect to unsubstituted OPPV. Several model compounds (with donating groups) exhibited high fluorescence quantum yields, from 51% to 68%. On the other hand, a very low yield was obtained for the oligomer with nitro groups, that was explained from semi-empirical calculations. These results showed promising properties for the incorporation of these oligomers in electroluminescent diodes

Cornstarch-mimosa tannin-urea formaldehyde resins as adhesives in the particleboard production

cited By 16International audienceThe objective of this work was to demonstrate the utilisation of cornstarch-mimosa tannin-based resins designed for application as an adhesive in particleboard production. Bond qualities of cornstarch-mimosa tannin-urea formaldehyde (UF) resins and commercial UF resin were assessed by using an automatic bonding evaluation system, prior to production of particleboards panels. In order to evaluate the quality of cornstarch-mimosa tannin-UF resins, particleboards were produced and physical and mechanical properties were investigated. These physical properties included rheological, thermogravimetric analysis and solid phase 13C NMR analysis of resins. Internal bond, surface soundness, thickness swelling, porosity, modulus of rupture and modulus of elasticity mechanical properties of particleboards bonded with cornstarch-mimosa tannin-UF resins were also determined. The results showed that it is possible to add cornstarch and mimosa tannin, respectively, up to 10 and 4% to the UF resin without to alter the physical and mechanical properties of the boards. The performance of these panels is comparable to those of boards made using commercial UF resin. Petrochemical UF resins could be partially substituted in industrial applications by addition of cornstarch and mimosa tannin extracts. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Diblock and random Donor/Acceptor "Double Cable" polythiophene copolymers via the GRIM method

International audienceIn this paper, we report the synthesis via the Grignard metathesis method (GRIM) of donor/ acceptor double cable copolymers with diblock and random sequences, where the conjugated polythiophene backbone is substituted with hexyl chains and with alkyl chains bearing fullerene. First, the monomers 2,5-dibromo-3-hexylthiophene and 2,5-dibromo-3-(l,3-dioxa-2-octyl)thiophene were randomly copolymerized and yielded after the grafting of fullerene C 60 the double cable CoPTR-C. Second, the same monomers were used to synthesize a diblock copolymer with a block made from a random copolymerization of both monomers while the second block is pure poly(3-hexylthiophene). After the grafting of fullerene, the block double cable CoPTBl-C was obtained. Both double cable copolymers were investigated through various characterization methods. NMR ID and 2D experiments allowed the full structural characterization and the determination of the final composition of the copolymers. The thermal behavior was investigated by TGA and DSC measurements, indicating that the incorporation of fullerene increased the thermal stability of the materials. The optical properties of these double cable copolymers were investigated by UV-visible absorption and fluorescence spectroscopy. The results showed no interaction at ground-state between the donor and acceptor moieties and a quenching of fluorescence of the polythiophene main chains in solution. AFM analysis on drop-casted films showed the dependence of the morphology of the double cable systems (random or diblock) on the aggregation. © 2008 American Chemical Society

Synthesis of Donor-Acceptor Multiblock Copolymers Incorporating Fullerene Backbone Repeat Units

The synthesis of the first example ()la block copolymer based on a polymer using fullerene as a backbone repeat subunit is demonstrated A facile route incorporating the electron acceptor and high fullerene content polymer, poly{(1,4-fullerene)-alt-[1,4-dimethylene-2,5-bis(cyclohexylmethylether)phenylene]} (PFDP), with the archetypal electron donor, poly(3-hexylthiophene) (P3HT), into a multiblock copolymer (M BC) structure is presented alpha,omega-Bromomethyl-PFDP was prepared by atom-transfer radical addition polymerization (ATRAP) and then reacted with alpha,omega-phenol-P3HT via a Williamson condensation to yield the MBCs The lengths of the electron-acceptor and donor polymer blocks could be selected so that the resulting solid state domains were of a size appropriate to organic solar cells Also 11 was found that the MBCs gave a wide range of macro-structures, from micelles to well-defined wires, depending on the preparation conditions

Formulation of Multifunctional Materials Based on the Reaction of Glyoxalated Lignins and a Nanoclay/Nanosilicate

International audienceTwo organosolv lignins from different origins, namely, almond shells and maritime pine, were modified by using a nanoclay and nanosilicate. Prior to modification, they were activated via glyoxalation to enhance the reactivity of the lignins and thus ease the introduction of the nanoparticles into their structure. The lignins were characterized by several techniques (Fourier transformed infrared, high-performance size exclusion chromatography, 1H NMR, X-ray diffraction, and thermogravimetric analysis) before and after modification to elucidate the main chemical and structural changes. The reaction with glyoxal proved to increase the amount of hydroxyl groups and methylene bridges. This tendency was more pronounced, as the percentage of glyoxal was incremented. On the other side, the addition of the nanoclay and nanosilicate particles improved the thermal stability of the lignins compared to that of the original unmodified ones. This trend was more evident for the lignin derived from maritime pine, which displayed better results regarding the thermal stability, indicating a more effective combination of the nanoparticles in the lignin structure during the modification process