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International audience; Thin-film composite of chitosan/nickel phthalocyanine (NiPc) was electrochemically deposited on the fingers of interdigitated gold electrodes, applying chronoamperometric polymerization technique. The presence of crystallized NiPc in the chitosan was confirmed by EDX and FTIR analysis. Acetone, ethanol, and methanol gas-sensing properties of the films prepared at optimum conditions were studied at atmospheric temperature, through differential measurements at an optimized frequency of 10 kHz, using a lock-in amplifier. The conductometric sensor presents the highest sensitivity of 60.2 μS.cm−1(v/v) for methanol and 700 ppm as the limit of detection. For validation, the methanol content of a commercial rubbing alcohol was determined.

A conductometric transducer is proposed for the first time for the detection of ethanol vapor. This ethanol microsensor is prepared by encapsulation of alcohol dehydrogenase (ADH) in chitosan. Interdigitated electrodes fabricated by silicon technology were used. The electrodeposition of chitosan allows the addressing of the chitosan film on the microconductometric devices and to encapsulate ADH and nicotinamide adenine dinucleotide (NAD+), which was monitored by FTIR. The analytical performance of the ethanol microsensor was determined in gaseous methanol, ethanol, and acetone samples, collected from the headspace above aqueous solutions of known concentration. The response time (tRec) of the sensor varies from 7 to 21 s from lower concentrations to higher concentrations. The detection limit is 0.12v/v % in the gas phase, corresponding to 0.22 M in the liquid phase. The relative standard deviation for the same sensor is from 12% for lower concentrations to 2% for higher concentrations. The ethanol sensor presents 2.6 times lower sensitivity for methanol and 28.3 times lower sensitivity for acetone. A detection of ethanol in the headspace of a red wine sample lead to an alcohol content in good agreement with the value given by the producer.

International audience; Increasing population and urbanization have direct consequences on the sewer functioning. In order to identify and quantify gases and VOCs likely to be present in the sewers, methodological studies of sampling in sewer using airbags, canisters and adsorbent tubes were assessed, and methods of analysis by GC-MS were developed. The results obtained lead to propose improvements to sampling protocols in the sewers. The gas quantification is complicated by low gas concentrations, environment heterogeneity and a high hygrometry.; Démographie et urbanisation croissantes ont des conséquences directes sur le fonctionnement des réseaux d’assainissement. Afin d’identifier, voire quantifier les gaz et les composés organiques volatils susceptibles d’être présents en réseau, des études méthodologiques de prélèvements en réseau, au moyen de sacs gonflables, canisters, tubes adsorbants, ont été explorées, et des méthodes d’analyses par chromatographie en phase gazeuse couplée à la spectrométrie de masse ont été mises au point. Les résultats obtenus permettent de proposer des améliorations des protocoles des prélèvements en réseau d’assainissement. La quantification des gaz est compliquée de par les faibles concentrations des espèces, l’hétérogénéité du milieu et une forte présence d’humidité.

International audience; A novel and ideal immunosensor platform with customized tailored chemistry is suggested by combining the characteristics of nanofibers (NFs) and dendrimers. Polystyrene (PS) NFs were doped with polyamidoamine (PAMAM) dendritic polymer and utilized for covalent immobilization of FITC-labeled anti-human TNF-alpha antibodies by activation of the amine groups of dendrimer on the surface of NFs using a glutaraldehyde (GA) coupling agent. SEM, ATR-FTIR, contact angle, EDX, XPS, TGA, and fluorescence microscopy were performed. The findings demonstrated that (1) PS-PAMAM NFs were produced with significantly smaller diameters (295 +/- 94 nm), more uniform morphology, and more hydrophilic (44 +/- 5.5 degrees) with dendrimer amine groups on the surface that can provide a better path for antibodies to be immobilized compared to pure PS NFs, (2) the PAMAM was distributed evenly throughout the NFs, (3) GA was uniformly applied to the surface of NFs via covalent bonding, (4) the PAMAM played a critical role in substantially increasing antibody immobilization at the surface of each NFs without causing agglomeration. According to the findings, the P5-PAMAM electrospun mat is suitable for immobilizing biomolecules and may be utilized as a support to boost immunosensor sensitivity.

International audience; Low methoxyl pectin is known to gel with divalent cations (e.g. Ca2+, Zn2+). In this study, a new way of pectin gelation in the presence of an active pharmaceutical ingredient, chlorhexidine (CX), was highlighted. Thus chlorhexidine interactions with pectin were investigated and compared with the well-known pectin/Ca2+ binding model. Gelation mechanisms were studied by several physico-chemical methods such as zeta potential, viscosity, size measurements and binding isotherm was determined by Proton Nuclear Magnetic Resonance Spectroscopy (H-1 NMR). The binding process exhibited similar first two steps for both divalent ions: a stoichiometric monocomplexation of the polymer followed by a dimerization step. However, stronger interactions were observed between pectin and chlorhexidine. Moreover, the dimerization step occurred under stoichiometric conditions with chlorhexidine whereas non-stoichiometric conditions were involved with calcium ions. In the case of chlorhexidine, an additional intermolecular binding occurred in a third step.

Compared to conventionnal bench top instruments, on-line GC analyzers require specific characteristics. On one hand, for some applications operating with a reactor pressure as high as several tens of bars, sample pressure has to be reduced before GC separation, or specific valves and columns have to be designed to perform separation with high carrier gas inlet pressure. On the other hand, informative detectors such as mass spectrometer are valuable but low maintenance detectors are prefered. To fit these two requirements (sampling at high pressure without decompression stage, and informative detector with low maintenance), short monolithic silica capillary column operated with inlet pressure as high as 60 bar has been hyphenated to VUV detector. Injection and column performance have been first investigated. The system has been optimized by adjusting split ratio at high pressure and by tuning two main VUV detector parameters (“average number” linked to data point averaging and make-up gas pressure) to decrease the limit of quantification. The optimization stage led to a set of experimental parameters which is a good compromise between signal-to-noise ratio and chromatographic efficiency. Finally, the hyphenated monolithic column has be used to partially separate a mixture of methane, ethane, carbon monoxide and carbon dioxide within 15 s, and the VUV deconvolution capabilities have been exploited to overcome coelution and finally separate individual signals.

International audience; In order to analyze light hydrocarbons mixtures with silica monolithic columns, a conventional gas chromatograph was modified to work with carrier gas pressure as high as 60bar. To understand hydrodynamic flow and retention with short columns (less than 30cm), special attention was required due to the temperature difference between the oven area and the FID detector which contain a significant length of the column. Efficiency and selectivity using various carrier gases (helium, nitrogen and carbon dioxide) at different inlet pressure for different oven temperature were studied. Carrier gas nature was a very significant parameter: on one side, linked to adsorption mechanism for gases like nitrogen and carbon dioxide onto the stationary phase modifying retention and selectivity, on the other side in relation to the minimum theoretical plate height which was as low as 15μm (66 000 platem(-1)) using carbon dioxide as carrier gas. The chromatographic system was then used to separate methane, ethane, ethylene, acetylene, propane, cyclopropane, and butane in less than 30s.

International audience; Are bioelectrochemical systems suitable to fight against the global warming provoked by the anthropogenic sources of CH4? None of the existing studies on this topic provide clear answers because the performance criteria of the electrochemical treatment and gas quantification methods used so far are questionable. This article redefines this performance criteria (carbon footprint - CF) and shows the importance of the materials and methods used to assess this criteria. Indeed, inappropriate gas quantification methods (pressure not taken into account, quantification only of CH4 and not of CO2) lead to errors on calculating the CF reduction rate from 22% to 68% in closed system. Moreover, this article demonstrates, based on suitable gas quantification methods and by means of triplicate MECs with the anode potential poised at +300 mV with respect to the Ag/AgCl reference, that it is possible to achieve a significant reduction in the CF of 22% of anaerobic biofilms producing CO2 and CH4.

SSCI-VIDE+CDFA+EDE:CPI:MBE; International audience; The hemicellulose-derived aqueous solution of C6 and C5 sugars (D-mannose, D-galactose, D-glucose, D-xylose, L-arabinose), obtained from the extraction and hydrolysis of the hemicellulosic polymers in softwoods prior to the production of pulp, was catalytically converted to the corresponding aldaric acids under alkaline (Pt/C) or native (Au-Pt/ZrO2) aqueous conditions with air. The inhibiting effect of some residual impurities and degraded compounds in the hydrolysate was confirmed, such as colored unsaturated compounds and 5-hydroxymethylfurfural. A combined purification process consisting of filtration, demineralization by ion-exchange resins, evaporation, and active carbon treatment of the raw aqueous-stream gave a purified hydrolysate of aldoses that was oxidized to hexaric and pentaric acids. The yields were dose to those of a synthetic solution of the pure sugars with the same distribution. The yields of aldaric acids accounted for ca. 50% of hexaric acids and up to 70% of pentaric acids.

The vacuum ultraviolet detector (VUV) is a very effective tool for chromatogram deconvolution and peak identification, and can also be used for quantification. To avoid quantitative issues in relation to time drift, such as variation of peak area or peak height, the detector response type has to be well defined. Due to the make-up flow and pressure regulation of make-up, the detector response (height of the peak) and peak area appeared to be dependent on experimental conditions such as inlet pressure and make-up pressure. Even if for some experimental conditions, VUV looks like mass-flow sensitive detector, it has been demonstrated that VUV is a concentration sensitive detector.

80% vinyltrimethoxysilane-based hybrid silica monoliths (80-VTMS), which have been initially developed for separation in reversed-phase liquid chromatography, have been investigated in high pressure gas chromatography separations (carrier gas pressure up to 60bar) and compared to silica monolithic columns. The behavior of both silica and 80-VTMS monolithic columns was investigated using helium, nitrogen and carbon dioxide as carrier gas. The efficiency of 80-VTMS monolithic columns was shown to vary differently than silica monolithic columns according to the temperature and the carrier gas used. Carrier gas nature was a significant parameter on the retention for both silica and vinyl columns in relation to its adsorption onto the stationary phase in such high pressure conditions. The comparison of retention and selectivity between 80-VTMS monoliths and silica was performed under helium using the logarithm of the retention factor according to the number of carbon atoms combined to Kovats indexes. The very good performances of these columns were demonstrated, allowing the separation of 8 compounds in less than 1min.

In this work, an enzymatic sensor, based on a bionanocomposite film consisting of a polyelectrolyte complex (PEC) (Chitosan/kappa-carrageenan) doped with gold nanoparticles (AuNPs) encapsulating glucose oxidase (GOD) deposited on a gold electrode (Au) for glucose sensing, is described. Using the electrocatalytic synergy of AuNPs and GOD as a model of enzyme, the variation of the current (&micro, A) as a function of the log of the glucose concentration (log [glucose]), shows three times higher sensitivity for the modified electrode (283.9) compared to that of the PEC/GOD modified electrode (93.7), with a detection limit of about 5 &micro, M and a linearity range between 10 &micro, M and 7 mM. The response of the PEC/AuNPs/GOD based biosensor also presents good reproducibility, stability, and negligible interfering effects from ascorbic acid, uric acid, urea, and creatinine. The applicability of the PEC/AuNPs/GOD based biosensor was tested in glucose-spiked saliva samples and acceptable recovery rates were obtained.

International audience; This paper presents the UV synthesis in miniemulsion of nanoparticles from hexyl acrylate monomers using radical photoinitiator type I benzoin methyl ether. The optimization of such a miniemulsion composition is studied to produce monodisperse nanoparticles with a mean size d p inferior to 200 nm after photopolymerization of the droplets. The correlation between the size distributions of the droplets and the corresponding nanoparticles was verified. Therefore, a composite design was built as regards to the amount of the surfactant (sodium dodecyl sulfate), the co-stabilizer (pentadecane), and the monomer (hexyl acrylate) in order to model the mean size and the polydispersity of the miniemulsion droplets. A range of monodisperse droplets size between 150 and 175 nm was achieved. After UV irradiation, high monomer conversion yield (>90 %) was reached leading to nanoparticles with mean size ranging from 100 to 165 nm. These hexyl acrylate nanoparticles have been obtained after 10 min of irradiation, offering new opportunities for nanoparticles synthesis in enclosed and/or plastic vessels.

The physicochemical and kinetic properties of resols prepared with different catalysts (NaOH, LiOH and Ba(OH)2) and variable formaldehyde/phenol ratios (2.5 £ R £ 3.5) were followed to determine their effects on the mechanisms and reaction products at a fixed pH and temperature. Kinetic monitoring and quantification of residual monomers were carried out by liquid chromatography coupled with mass spectrometry (LC/UV/MS), by 13C nuclear magnetic resonance (NMR) and by chemical assay for formaldehyde. Oligomer formation (n ≥ 2) was determined by LC/UV/MS, size exclusion chromatography (SEC) and 13C NMR. It was found that minor compounds form during syntheses (phenol methanol hemiacetals, hemiacetals of phenol and of oligomers…) and that the ratio R affects primarily the kinetics of formation of monomers and oligomers, in contrast to the catalysts that modify reaction mechanisms. The understanding of the structure of the resols was an important step for the determination of the final properties of the material.

International audience; New biosourced alternated poly(ether)Ester-Amides PeEA were prepared by polycondensation in solution or in bulk of unprecedented aminoalcohols based on 1,4:3,6-dianhydrohexitols (DAH) with aromatic and aliphatic diacyl chlorides (sebacoyl, terephtaloyl and isophtaloyl). Optimization of the polymerization in solution has been investigated using MALDI ToF MS and NMR spectroscopy to ascertain the structures and end chain nature of the resulting polymers. The influence of the DAH stereochemistry and the polymerization mode on the structures and thermal properties was demonstrated by MALDI ToF and complementary analytical techniques (DSC and SEC). Isomannide based polymers revealed amorphous but showed higher Tg (around 80 °C for sebacoyl and 180 °C for isophtaloyl) whereas the isosorbide based polymers were semi crystalline. Best properties were obtained in bulk using isomannide based aminoalcohol and sebacoyl chloride (Tg of 82 °C and Mw of 32 kDa, PDI = 1.41).

1,3,5-Tris(4-fluorobenzoyl)benzene (TFBB) and 2,6,4′-trifluorobenzophenone (TFB) were polycondensed with isosorbide and isomanide. All polycondensations were performed in a mixture of dimethyl sulfoxide and toluene with potassium carbonate as promotor. Optimal concentration to avoid gelation was set at 0.06 mol L−1. The different cyclization tendencies on the basis of monomers conformations are discussed. In the TFB series, the feed ratio isosorbide/TFB was varied from 1.0:1.0 to 1.5:1.0. A majority of linear and hyperbranched species were identified as main reaction products by matrix-assisted laser desorption/ionization–time-of-flight mass spectrometry regardless of the diol with slight cyclization tendency for isomannide. When TFBB was polycondensed with isosorbide, the cyclization tendency was significantly improved. The products obtained at a feed ratio of 1.41/1.0 and 1.51/1.0 were rich in cyclic and multicyclic species. More interesting results were obtained from the polycondensation of TFBB and isomannide, giving rise majoritarily to cyclic, bicyclic, and multicyclic species. Differential scanning calorimetric measurements indicated high glass transition temperature (around 200°C).

International audience; New series of polyether-amides were prepared by polycondensation in solution of three diamines based on 1,4-3,6-dianhydrohexitols with two types of diacyl chlorides (sebacoyl and isophtaloyl). Unprecedented diamines based on isomannide and isoidide were elaborated. The corresponding polyether-amides (PeA) were obtained with high yields. They were characterized by different analytical techniques (NMR, MALDI-ToF MS, DSC). The combination of MALDI-ToF MS with NMR spectroscopy allowed us to confirm structure types. DSC measurements revealed an amorphous character for the isophtaloyl family with a high Tg value. The sebacoyl series proved to be semi-crystalline with a high Tm value. Isosorbide-based PeAs demonstrated interesting properties (Tg above 210 °C and Tm above 240 °C) and high viscosity (0.32).

The treatment of waste containing nanoparticles (NP) will become a matter of first importance being given the increasing production and use of engineered NP. At present no specific end of life treatment is planned for such waste and most of the time it follows the path of conventional waste in incineration plants. The study of the behavior of NP at high temperature may help to define dedicated procedures and eventually lead to new regulations. This work deals with the set up of an incineration mounting at a laboratory scale. This assembly tested on NP samples shows significant results and interesting trends.

The lids of beverage cans are coated with varnish before stamping. In light of the considerable stress undergone by the metal during stamping, the coefficient of friction of the cross-linked coating must be optimised. To this end, the compounder can add lubricants to the varnish matrix. After heat treatment of the varnish, they contribute to the success of the stamping process. The present work describes the use of Fourier transform infrared spectroscopy and differential scanning calorimetry to characterise these mixtures of lubricants and to assay them in situ in the varnish.

Although the thermal degradation of polyurethanes has been extensively studied in the past, the use of a panoply of recent analytical techniques has provided more detailed data and enabled us to confirm prior findings on the thermal degradation of bicomponent polyurethanes. The thermal behaviour of bicomponent polyurethanes in conditions of controlled atmosphere and temperature was characterized by determining their heat stability by on-line TGA/FT-IR coupling and off-line TGA/TCT/GC/MS coupling in order to identify the volatile compounds released. Degradation residues were analyzed by FT-IR and MALDI-TOF (matrix assisted laser desorption/ionization coupled with time-of-flight) mass spectrometry. A major drawback of these thermoplastic elastomers is that one of the components, isocyanate, is toxic. Based on the data obtained with model urethane compounds ( p-TI-based) and bicomponent polyurethane polymer (MDI- and PEG-based), we show that the thermal degradations are different. The widespread application of these materials exposes them to extreme working conditions, which is why we propose reaction mechanisms for their degradation.

In order to understand the single-step molten state reactivities of a diaromatic isocyanate (4,4’ dPDhenylmethane diisocyanate MDI), the mechanisms and reaction kinetics were modelled using a monofunctional aromatic isocyanate (para-tolyisocyanate p-TI) and hydroxytelechelic polyols (polyethylene glycol PEG) (polypropylene glycol PPG) with variable macromolecular chains and structure (from 200 to 2000 g.mol-1). The molar ratio of reactive functions NCO/OH was set at 1.1. We were able to characterise the bi-component polyurethanes synthesised and identify side products formed (urea, trimer, allophanate…). The results were obtained by the use of a panoply of classical analytical techniques (NMR, FTIR, HPLC/UV/MS, ESI/MS, DSC) or those more recent in the field of synthetic polymers (MALDI-TOF). This work shows the necessity of using several efficient and complementary techniques in order to understand the molten state reaction mechanisms and kinetics of these complex PU systems.

Heavy metals adsorbents were prepared by co-condensation of tetraethoxysilane and functionalized trialkoxysilane RSi(OR′)3. Functionalized porous silicas with aminopropyl (H2N(CH2)3-), [amino-ethylamino]propyl- (H2N-(CH2)2-NH(CH2)3), (2-aminoethylamino)-ethylamino]propyl (H2N-(CH2)2-NH-(CH2)2-NH(CH2)3-), and mercaptopropyl (HS-(CH2)3-) groups were synthesized using dodecylamine as structure directing agent. These materials have been characterized by elemental analysis, powder X-ray diffraction, nitrogen gas sorption, Fourier transform infrared and Raman spectroscopies and thermogravimetric analysis. These organo-silicas were prepared for use in the removal of heavy metal ions from aqueous solutions. Samples synthesized with [amino-ethylamino]propyl- and (2-aminoethylamino)ethylamino]propyl- functions show a high loading capacity for Cu2+, Ni2+, Co2+ and the anion Cr(VI). The sample synthesized with a mercaptopropyl function has a high loading capacity for Cd2+.

The study involved the thermal degradation of phenolic resins in controlled atmospheres (inert and oxidizing). Its aim was to characterize volatile organic compounds (VOC) and inorganic compounds released during heat treatment. The methods used were thermogravimetry coupled with thermodesorption/gas chromatography/mass spectrometry (TG/TCT/GC/MS) and thermogravimetric analysis coupled with infrared (TGA/IR). At the end of the heat cycle, residues were characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (solid state 13C NMR (CP/MAS)). The data show that the synthesis conditions of the crosslinked resins, the controlled environment and the temperature of the degradation heat cycle, all affect the composition of volatile compounds and residues at the end of the cycle. The data have enabled us to propose decomposition reaction mechanisms for these resins in oxidizing and inert environments.

International audience; We report the results of a study on the thermal degradation of cyanate prepolymers and corresponding materials prepared in the molten state by the homopolymerization of monomers in a controlled atmosphere (nitrogen) and in the temperature range of 100 to 500degreesC. We propose degradation mechanisms for these materials based on the analysis of physicochemical data obtained by the differential scanning calorimetry, thermogravimetric analysis, gas chromatography-mass spectrometry and Fourier transform infrared spectroscopy of volatile organic compounds and residues after the thermal cycle. These mechanisms depend on the structure of the carbon skeleton.

International audience; Monitoring the homopolymerization of cyanate monomers during heat treatment shows that triazine rings formed during the 180 degreesC step. Oligomers were composed of 1 to 15 triazine rings. Analysis of compounds formed before the gel point revealed the presence of side products containing terminal phenolic functions: the phenol-cyanate (M-0-OH) and oligomers with one or two hydroxyl functions (M-1.2,...-OH). Kinetic and mechanistic monitoring during treatment at 210 degreesC in the solid state allowed the determination of the structure of the final system and the detection and quantification of unreacted cyanate functions. Kinetic and thermal studies in the temperature range of 100 to 220 degreesC showed that the homopolymerization of hexafluorobisphenol A dicyanate starts at a lower temperature and is slower than that of bisphenol A dicyanate. Thermogravimetric data showed that residual monomers volatilized between 150 and 300 degreesC, while the degradation of crosslinked products occurred between 400 and 600 degreesC and involved two distinct steps.

The liquid study of propargylic monomers during heat treatment has shown the formation of secondary phenolic products in the reaction mixture. They are in the form of propargyl-phenol and chromene-phenol and could be the weak links in the thermal properties of the final polymer. Moreover, we note some differences between the reactivities of the two monomers, probably related to the nature of the central pivot of the skeleton. Solid state analyses by FTIR and solid state crossed polarization magic angle spinning 13C NMR have confirmed the structure of the final polymer, and the reaction paths proposed and have enabled the heat cycle used to be validated. Thermal analyses have shown that the fluorine pivot confers the best thermal properties on the crosslinked material and influences the reactivity and degradation mechanisms of the compounds. In addition, the degradation of the crosslinked compounds occurred as a single step for the dipropargyl ether of bisphenol A and as two steps for the dipropargyl ether of hexafluorobisphenol A.

The heat stability and thermal degradation of two acetylene-chromene terminated polymers, called polyA (polymer of 6,6′-isopropyl dichroman) and polyF (polymer of 6,6′-hexafluoroisopropyl dichroman) were investigated in controlled conditions. The environmental impact of their degradation was studied in order to predict their remediation and fate after use. Degradation of the polymers was followed by dynamic thermogravimetric analysis (TGA). Both polymers degraded starting at 350°C, according to a single mechanism for polyA and two distinct mechanisms for polyF. In addition, the isothermal TGA study of thermal ageing for 24 hours showed that both compounds were very stable at 250°C (losses of mass less than 3%) and that polyF was more stable than polyA when heated between 350 and 550°C. Degradation residues were analyzed by infrared-Fourier transform spectroscopy (FT-IR). Volatile organic compounds (VOC) released by pyrolysis were analyzed by pyrolysis/thermal desorption cold trap/gas chromatography/mass spectrometry. These methods enabled us to determine degradation mechanisms in the same temperature interval. The data showed that the major part of the degradation occurred in the cyclic ether, with breaks at cross-linking nodes and C–O bonds. Since the skeletons of the cross-linking nodes of both compounds were identical, the higher stability can be attributed to the presence of fluorine in its central hexafluorinated pivot, providing greater heat stability than the isopropyl pivot in polyA.

The physicochemical characterization of the structures of the oligomers (n < 4) in resols has been carried out by fragmenting monomers in LC/UV/MS and LC/UV/MS/MS. Fragmentation mechanisms are related to the numbers and positions of substituents on the aromatic ring and to the types of oligomer junctions. It was more difficult to determine the structures of phenol hemiacetals and dimer hemiacetals because of the large number of position isomers. The resols were prepared with differing molar ratios R = Formaldehyde/Phenol and catalysts. They were cross-linked using two industrially recommended heat cycles. The progression of resin cross-linking was determined by solid state 13C NMR (CP/MAS). The residual percentage of monomers and oligomers at n < 4 was determined in leachates (water and methanol) and characterized by LC/UV/MS. The results for cross-linking advancement were correlated with the various synthesis parameters (ratio R, type of catalyst and heat cycle).