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31.
Dr. Ilhem Khelifi Shannon Pecnard Dr. Guillaume Bernadat Dr. Jérome Bignon Dr. Hélène Levaique Dr. Joëlle Dubois Dr. Olivier Provot Dr. Mouad Alami 《ChemMedChem》2020,15(16):1571-1578
In this article, we report the synthesis and biological properties of a series of novel oxazepines related to isoCA-4 having significant antitumor properties. Among them, three oxazepin-9-ol derivatives display a nanomolar or a sub-nanomolar cytotoxicity level against five human cancer cell lines (HCT116, U87, A549, MCF7, and K562). It was demonstrated that the lead compound in this series inhibits tubulin assembly with an IC50 value of 1 μM and totally arrests the cellular cycle in the G2/M phase at the low concentration of 5 nM in HCT116 and K562 cells. Molecular modeling studies perfectly corroborates these promising results. 相似文献
32.
Design of New Cardanol Derivative: Synthesis and Application as Potential Biobased Plasticizer for Poly(lactide) 下载免费PDF全文
Fatima Hassouma Iulia Mihai Ludivine Fetzer Thierry Fouquet Jean‐Marie Raquez Abdelghani Laachachi Hicham Ibn Al Ahrach Philippe Dubois 《大分子材料与工程》2016,301(10):1267-1278
A novel biobased plasticizer made of cardanol is designed for poly(lactide) (PLA). This cardanol‐derived plasticizer, i.e., methoxylated hydroxyethyl cardanol (MeCard), is synthesized through methoxylation of the double bonds on the side chain of cardanol, and characterized by 1H NMR and mass spectrometry. The plasticization effect of MeCard on the molecular structure, morphology, thermal and mechanical properties of PLA is evaluated and compared to that of a commercial cardanol, i.e., hydroxyethyl cardanol (pCard). The plasticization efficiency of MeCard is demonstrated by a substantial decrease of the glass transition temperature and storage modulus together with a significant increase of the elongation at break as compared to neat PLA. Moreover, MeCard exhibits higher plasticization performance than pCard toward PLA. Such behavior is related to a higher miscibility and compatibility between PLA and MeCard thanks to the methoxylation of the double bonds on the side chain of cardanol as shown by SEM micrographs.
33.
This review reports on recent advances in the design of biodegradable polymers built from petroleum and renewable resources using reactive extrusion processing. Reactive extrusion represents a unique tool to manufacture biodegradable polymers upon different types of reactive modification in a cost‐effective way. Partially based on our ongoing research, ring‐opening polymerization of biodegradable polyesters will be approached as well as the chemical modification of biodegradable polymers, particularly natural polymers. The development of environmentally friendly polymer blends as well as (nano)composites from natural polymers, including natural fibers and nanoclays, through reactive extrusion, as an efficient way to improve the interfacial adhesion between these components, will be also discussed.
34.
Vapor barrier properties of polycaprolactone montmorillonite nanocomposites: effect of clay dispersion 总被引:3,自引:0,他引:3
Giuliana GorrasiMariarosaria Tortora Vittoria Vittoria Eric PolletBénédicte Lepoittevin Michael AlexandrePhilippe Dubois 《Polymer》2003,44(8):2271-2279
Different compositions of poly(ε-caprolactone) (PCL) and (organo-modified) montmorillonite were prepared by melt blending or catalyzed ring opening polymerization of ε-caprolactone. Microphase composites were obtained by direct melt blending of PCL and sodium montmorillonite (MMT-Na+). Exfoliated nanocomposites were obtained by in situ ring opening polymerization of ε-caprolactone with an organo-modified montmorillonite (MMT-(OH)2) by using dibutyltin dimethoxide as an initiator/catalyst. Intercalated nanocomposites were formed either by melt blending with organo-modified montmorillonite or in situ polymerization within sodium montmorillonite. The barrier properties were studied for water vapor and dichloromethane as an organic solvent. The sorption (S) and the zero concentration diffusion coefficient (D0) were evaluated for both vapors. The water sorption increases with increasing the MMT content, particularly for the microcomposites containing the unmodified MMT-Na+. The thermodynamic diffusion parameters, D0, were compared to the value of the parent PCL: both microcomposites and intercalated nanocomposites show diffusion parameters very near to PCL. At variance exfoliated nanocomposites show much lower values, even for small montmorillonite content. In the case of the organic vapor, the value of sorption at low relative pressure is mainly dominated by the amorphous fraction present in the samples, not showing any preferential adsorption on the inorganic component. At high relative pressure the isotherms showed an exponential increase of sorption, due to plasticization of the polyester matrix. The D0 parameters were also compared to those of the unfilled PCL; in this case, both the exfoliated and the intercalated samples showed lower values, due to a more tortuous path for the penetrant molecules. 相似文献
35.
Jean‐Marie Raquez Philippe Degee Philippe Dubois Sunder Balakrishnan Ramani Narayan 《Polymer Engineering and Science》2005,45(4):622-629
Bulk polymerization of ?‐caprolactone (CL), 1,4‐dioxan‐2‐one (PDX), and mixtures of PDX and CL was carried out by initiation with Al(OsecBu)3 in a co‐rotating twin‐screw extruder through a fast single‐step process. Both homopolymerizations and copolymerization of PDX and CL proceed very rapidly and reach almost complete (co)‐ monomer(s) conversion as soon as 8 mol% of CL are added in the feed. Even though poly(1,4‐dioxan‐2‐one) (PPDX) is known to thermally degrade mainly through unzipping depolymerization promoted from the hydroxyl end‐groups and yielding PDX monomer, it turns out that the thermal stability of PPDX chains is substantially improved by the copolymerization of PDX with limited amounts of CL. Interestingly, DSC analysis of the so‐obtained P(PDX‐co‐CL) copolymers has demonstrated that a CL molar fraction as high as 11 mol% does not prevent the crystallization of the resulting copolymer, which retains a melting temperature close to 95°C. This last observation has been explained by the formation of a blocky‐like copolymer structure, in which short PPDX and PCL sequences are randomly distributed. POLYM. ENG. SCI., 45:622–629, 2005. © 2005 Society of Plastics Engineers. 相似文献
36.
NMR and EPR studies of room temperature highly fluorinated graphite heat-treated under fluorine atmosphere 总被引:1,自引:0,他引:1
Semi-ionic carbon fluoride obtained by reaction of graphite with a gaseous mixture of IF5, HF and F2 was modified by a post-fluorination at various temperatures in the range 100-680 °C. The resulting materials were studied by 19F-NMR and EPR both at room temperature and at different experimental temperatures from 200 to 360 K and from 100 to 473 K for NMR and EPR experiments, respectively. 19F-NMR gives information about the residual intercalated iodine fluoride species (IF5, IF6− and IF7) such as the temperature of their removal from the host fluorocarbon matrix and their mobility into the interlayer space. The nature of the C-F bonding was investigated by 19F-NMR, MAS/13C-NMR, FT-IR spectroscopy and X-ray diffraction. The C-F bonding changes from semi-ionic to a mainly covalent character at a fluorination post-treatment temperature close to 450 °C. This transformation coincides with the removal of the iodine fluoride species from the host structure. The densities of the paramagnetic dangling bonds were studied by EPR; this technique allows also to investigate the local environment of the dangling bonds in the fully fluorinated samples (obtained with fluorination post-treatment temperatures higher than 450 °C). As a matter of fact, an hyperfine structure was observed for these samples; it results from interaction of the dangling bond electron with six neighboring fluorine nuclei. The role of the intercalated species (iodine fluoride compounds and HF) on the mechanisms of the extra-fluorination is also discussed. 相似文献
37.
Quantitative Fourier transform infrared analysis for anisidine value and aldehydes in thermally stressed oils 总被引:5,自引:0,他引:5
J. Dubois F. R. van de Voort J. Sedman A. A. Ismail H. R. Ramaswamy 《Journal of the American Oil Chemists' Society》1996,73(6):787-794
A Fourier transform infrared (FTIR) transmission-based spectroscopic method was investigated for the simultaneous monitoring
of aldehyde formation and the determination of anisidine value (AV) in thermally stressed oils. Synthetic calibration standards
were prepared by adding known amounts of hexanal,t-2-hexenal andt,t-2,4-decadienal to canola oil (these compounds considered representative of aldehydic compounds formed during oxidation) plus
random amounts of other compounds representative of oxidation by-products. The standards were analyzed for their chemical
AV. With the partial least squares (PLS) technique, an FTIR spectrometer was calibrated to predict both the concentrations
of individual aldehyde types and AV, with the individual aldehyde contributions being related to the chemical AV by multiple
linear regression to derive “apparent” AV values. The predictive capability of the PLS calibrations was assessed by analyzing
canola oils that were thermally stressed at 120, 155, and 200°C. The apparent AV, predicted for these samples, matched the
chemical AV values within ±1.65 AV units. A PLS calibration also was derived by using thermally stressed samples as calibration
standards. This approach provided similar predictive accuracy as the use of synthetic calibration standards. As such, quantitative
determination of AV by FTIR spectroscopy was shown to be feasible, and the synthetic calibration approach provided additional
information on the aldehyde types present in a sample and allowed the use of a simple gravimetric approach for calibrating
an FTIR spectrometer. This study provides the basis for the development of a rapid, automated FTIR method for the direct analysis
for AV of thermally stressed fats and oils in their neat form without the use of chemical reagents. The implementation of
such a method as a quality control tool would eliminate the use and disposal of hazardous solvents and reagents, required
by the conventional chemical method, and drastically reduce analysis time (∼2 min/sample). Possible applications include monitoring
of the oxidative state of frying oils or evaluation of oxidative stability of biodegradable lubricants. 相似文献
38.
Véronique Gauthier Benoît Cochepin Sylvain Dubois Dominique Vrel 《Journal of the American Ceramic Society》2006,89(9):2899-2907
Ti3 SiC2 is synthesized by self-propagating high-temperature synthesis (SHS) of elemental titanium, silicon, and graphite powders. The reaction paths and structure evolution are studied in situ during the SHS of the 3Ti+Si+2C mixture by time-resolved X-ray diffraction coupled with infrared thermography. The proposed reaction mechanism suggests that Ti3 SiC2 might be formed from Ti–Si liquid phase and solid TiC x . Finally, the effect of the powders starting composition on the Ti3 SiC2 synthesis is studied. For the investigated initial mixtures, TiC x is always formed as a major impurity together with the Ti3 SiC2 phase. 相似文献
39.
40.
The analytical parameters for the measurement of mercury in air have been investigated for the integrated silver method. The ultimate sensitivity of the method and the reproducibility of the standard curve are discussed. The proper storage of the activated silver absorber is described, as well as the storage of a mercury-air sample on the silver element.The collection efficiency for mercury has been found to be quantitatively reversible, with respect to both capture and release. The collection process on silver is highly specific for mercury. Benzene, for example, is not retained on silver, though it can give a spurious response when sampled directly by a “continuous” ultraviolet photometer. Most commonly encountered organic vapors, which give a response at mercury absorption wavelengths, are not retained by the silver element and do not, therefore, interfere with subsequent ultraviolet measurement of the desorbed mercury vapor.For ambient air sampling, the optimum flow-rate was found to be 1.51/min. This also proved to be a suitable flow-rate for desorption and assay. Pure air, as carrier, has been found to be satisfactory, since no differences have been noticed when comparative measurements have been made using inert gases.Instrumental measurement by means of a digital integrator has been found to be superior to a recorder output using peak height. Peak area measurement, by integrator, is not affected by the rate of diffusion of the mercury vapor within the sampling system and optical train. 相似文献