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Glucuronoxylanases are endo-xylanases and members of the glycoside hydrolase family 30 subfamilies 7 (GH30-7) and 8 (GH30-8). Unlike for the well-studied GH30-8 enzymes, the structural and functional characteristics of GH30-7 enzymes remain poorly understood. Here, we report the catalytic properties and three-dimensional structure of GH30-7 xylanase B (Xyn30B) identified from the cellulolytic fungus Talaromyces cellulolyticus Xyn30B efficiently degraded glucuronoxylan to acidic xylooligosaccharides (XOSs), including an α-1,2-linked 4-O-methyl-d-glucuronosyl substituent (MeGlcA). Rapid analysis with negative-mode electrospray-ionization multistage MS (ESI(-)-MS n ) revealed that the structures of the acidic XOS products are the same as those of the hydrolysates (MeGlcA2Xyl n , n > 2) obtained with typical glucuronoxylanases. Acidic XOS products were further degraded by Xyn30B, releasing first xylobiose and then xylotetraose and xylohexaose as transglycosylation products. This hydrolase reaction was unique to Xyn30B, and the substrate was cleaved at the xylobiose unit from its nonreducing end, indicating that Xyn30B is a bifunctional enzyme possessing both endo-glucuronoxylanase and exo-xylobiohydrolase activities. The crystal structure of Xyn30B was determined as the first structure of a GH30-7 xylanase at 2.25 A resolution, revealing that Xyn30B is composed of a pseudo-(α/β)8-catalytic domain, lacking an α6 helix, and a small β-rich domain. This structure and site-directed mutagenesis clarified that Arg46, conserved in GH30-7 glucuronoxylanases, is a critical residue for MeGlcA appendage-dependent xylan degradation. The structural comparison between Xyn30B and the GH30-8 enzymes suggests that Asn93 in the β2-α2 loop is involved in xylobiohydrolase activity. In summary, our findings indicate that Xyn30B is a bifunctional endo- and exo-xylanase.

The Kendrick mass defect (KMD) analysis conveniently turns a complex high-resolution mass spectrum into a compositional map with informative clustering of points depending on the elemental composition of the associated ions. It has nevertheless been left unchanged for thirty years with the use of chemical moieties such as methylene as base units for the computation of “regular” mass defects displayed in condensed plots regardless of the samples. The concept of “resolution-enhanced” KMD analysis using the mass of the repeating unit divided by an integer as the new fractional base unit has been recently introduced for the computation of expanded plots from polymeric mass spectral data with a dramatically improved separation of ion series. This user-friendly data processing is extended to the case of carbonaceous samples for the first time with the analysis of water-insoluble organic microspheres recovered from the hydrothermal extraction of wood and coals. In a didactic discussion with illustrative examples, the direct resolution-enhanced KMD analysis, the consecutive resolution-enhanced analysis of a part of a regular KMD plot or the systematic slicing of plots in a multistep procedure are shown to produce simple resolution-enhanced KMD plots or resolution-enhanced zooming from complex mass spectra. The combination of these techniques in a unique “advanced KMD analysis” toolkit is expected to revolutionize the data processing of high-resolution mass spectra with unprecedented separating and unraveling capabilities.

Coal organic microspheres (COM), a novel material originated from the organic components of coal, were obtained from brown coal directly using a one-step treatment in a flow of water. Here, we studied in detail the effect of hydrothermal conditions on morphology, yield, elemental composition, functional groups, and molecular composition of COM, at temperatures of 250, 300, 350, and 380 °C, pressures of 4, 10, 20, and 24 MPa, and holding times of 0, 30, 60, and 90 min. The holding time influences COM production: longer holding time leads to higher yields and larger particle size. The hydrothermal temperature and pressure, which control the properties of water, have a significant influence on the yield, shape, and particle size of COM. The properties of water affect the COM yields as follows: 1) when the phase of water is liquid, the lower density, viscosity, and static dielectric constant gives higher yields; 2) the yield obtained in supercritical water is higher than that in subcritical water; 3) phase transformation of water from liquid to gas decreases the yield. Additionally, the particle size of COM can be controlled by the temperature, and the pressure affects the shape of COM greatly; even nano-sized particles are produced at 350 °C and 10 MPa. From the molecular composition results, low-molecular weight compounds with small double bond equivalents decompose under supercritical water condition. Large amounts of organic compounds in brown coal are thermally decomposed and extracted under hydrothermal conditions, and then spherical COM particles form and grow from small to big during the cooling process. These results are helpful for clarifying the formation mechanism of COM, and enable control of COM yield and properties.

Paper spray ionization coupled with a high-resolution time-of-flight mass spectrometer was applied to the analysis of 13 block and 2 random ethylene oxide/propylene oxide (EO/PO) copolymers as well as to standard samples of poly(ethylene oxide) and poly(propylene oxide) homopolymers. Paper spray mass spectra could be obtained rapidly and, unlike electrospray ionization, were not subject to contamination and sample carryover. For comparison, polyether samples were also measured on a MALDI/TOF system with ultrahigh mass resolving power. MALDI/high-resolution time-of-flight mass spectrometry exhibited single-charge ions characteristic of the polymer distributions whereas the paper spray mass spectra exhibited charge states ranging from one to six charges. Kendrick mass defect plots of the multiple-charge ions in the paper spray mass spectra exhibit isotopic splitting of the Kendrick mass defects, facilitating visualization of the number of charges in each series. The slope of the KMD plots can be used to estimate the percentage of ethylene oxide in the copolymers. In-source fragmentation permitted the distinction between block and random copolymers.

Protective coatings from diethylphosphatoethyltriethoxysilane (DEPETS) have been deposited on different polymer substrates in a plasma discharge operated at atmospheric pressure. Plasma polymer chemistry and structure were characterized by means of Fourier transform infrared spectroscopy (FTIR), laser desorption ionization-mass spectrometry (LDI-MS), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM). A chemical structure of the plasma polymer has been proposed based on the coating molecular characterization. Coatings were deposited on polycarbonate (PC) and polyamide 6 (PA6) substrates. The flame retardant properties of coated substrate samples were assessed using cone calorimetry and compared to those of bare substrates. A significant increase in the time to ignition (TTI), up to +143%, was recorded after coating deposition due to the formation of a high-performance barrier layer at the surface of both polymer substrates.

The network structure of polybenzoxazines is known to be supported by strong inter- and intra-molecular hydrogen bonds. Kaolin, a platelet clay mineral, possesses similar supramolecular interactions, preventing its platelets from exfoliation when mixed with polymers. In the present study, demonstration of the ability of 3,3′-ethane-1,2-diylbis(3,4-dihydro-2H-1,3-benzoxazine) (EDBZ) to assembly onto kaolin surface through hydrogen bonding is given by Fourier transform infrared spectroscopy (FTIR). Composites were subsequently prepared by a convenient solventless method, leading to high performance materials with improved thermal and thermo-mechanical properties. As the improvement of the thermo-mechanical properties could be due to a catalytic effect of the clay interlayer cations, Sepiolite – a mineral clay with a similar cation exchange capacity than kaolin but with a far lower OH group content – was used to prepared composites. Similar crosslinking kinetics of EDBZ are obtained for composites prepared with either kaolin or sepiolite. However the dispersion state of sepiolite is disastrous, whereas kaolin is finely dispersed thanks to its higher OH group content, highlighting the predominant role of H-bonding interactions onto kaolin dispersion within EDBZ.

It is well established that the chemical structure of surfactants used to promote the dispersion of clay minerals in polymers plays a major role in clay polymer nanocomposites preparation. However, much less explored is the incorporation of reactive surfactants capable of covalently grafting to monomers and polymer chains. In this work, the effect of the reactivity degree of bio-based surfactants onto the exfoliation of montmorillonite in epoxy is evidenced. For this purpose, 3 surfactants were prepared from a derivative of Cardanol, incorporating reactive groups: N(CH 3 ) 2 , NH 2 or two NH 2 functions. In each case, the organomodification of the clay mineral results in a similar interlayer space increase. Combined chemical derivatization and MALDI-TOF/MS was used to evidence the differences of the residual reactivity of the intercalated surfactants. Finally each organomodified clay mineral was used for the preparation of epoxy nanocomposites. Interestingly, for the most reactive surfactant, X-ray diffraction analysis evidenced a fully exfoliated structure while semi-exfoliation or intercalated structure was found for the less reactive surfactants.

A polymeric bilayer composed of two poly(styrene) layers differing by their molecular weights (MW) was elaborated to mimic a MW gradient and analyzed by a combination of TOF-SIMS, MALDI-MS and Nanoscratch (NS). A direct TOF-SIMS profiling conducted using a Cs+ ion beam lead to the detection of fragments from carbonated layers without any data about their MW, making the fine bilayer architecture indistinguishable. Spots of various depths were hence created using the same Cs+ ion bombardment for different sputtering times, and further mass-analyzed by the recently developed Surface-Layer MALDI-MS technique, to evaluate the MW of the very top polymeric layer of each crater. The off-line combination of ion etching and LASER analysis allowed a molecular weight depth profile to be plotted, as a function of the physical depth measured by NS in each crater (instead of the usual sputter time). This original coupling is expected to provide useful molecular and/or molecular weight data about complex organic and/or polymeric multi-layers or gradients.

A new ammonium-based surfactant (PkH + ), synthesized from a 3-alkyl phenol glycidyl ether issued from renewable cashew nutshell liquid (CNSL), has been used to modify the surface of sepiolite clay. This surfactant is especially designed to enhance the compatibility of the needle-like clays with epoxy networks (e.g. DGEBA): ionic PkH + –sepiolite interactions are provided by the ammonium groups, and covalent grafting of DGEBA onto the surfactant is enabled by NH and OH reactive groups. MALDI-ToF-MS was used with success to evidence the grafting of DGEBA units onto the modified clay. Morphological analyses by SEM highlighted the promoted compatibilization and dispersion of sepiolite in DGEBA networks. The properties of the filled networks were characterized by DSC, DMA and evidenced a strong shift of 20 °C of the Tg of the network to higher temperatures and an enhancement of the storage modulus below the Tg. Interestingly, the thermal stability of the network was not affected by the modification of sepiolite by the ammonium. In conclusion, the intercalation of PkH + onto sepiolite subserves its compatibilization into epoxy networks with a remarkable thermal and thermomechanical properties improvement.