Patenting activity in manufacturing organoclays for nanocomposite applications

peer reviewedFor the last two decades, intensive research has been focused on developing reinforced polymers with incorporation of nanometric fillers. Amongst the different types of nanofillers, those based on layered silicates (commonly known as clays), have been most widely investigated. Dispersing clay sheets on a nanoscopic scale (so-called exfoliation) indeed allows materials with enhanced thermal, mechanical, rheological, flame retardancy and barrier properties to be produced. However, the nanocomposite performances are strongly dependent upon the extent of clay exfoliation. In order to enhance the compatibility between the pristine clay, hydrophilic, and the polymer, hydrophobic, and to achieve a good delamination of the nanolayers, an organo-modification of the clay is most usually necessary. This mini-review will provide an outline of patenting activity in the field of manufacturing organoclays through ionic exchange. The variety of organic modifiers and the diverse processing techniques will be detailed, aiming to extract the most relevant organoclays for successful nanocomposite formation at industrial scale

“One-pot” dispersion ATRP and alkyne-azide Huisgen’s 1,3-dipolar cycloaddition in supercritical carbon dioxide: towards the formation of functional microspheres

Functional polymers were successfully prepared in scCO2 by combining alkyne-azide 1,3-dipolar Huisgen’s cycloaddition and dispersion ATRP in a “one pot” process using new perfluorinated polymeric amino-based ligands that had a dual role, i.e. the complexation of the copper catalyst and the stabilization of growing particles

Cobalt mediated radical polymerization (CMRP) using bis(acetylacetonato)cobalt(II): a unique tool for controlling the radical polymerization of conjugated and unconjugated vinyl monomers

Cobalt-Mediated Radical Polymerization (CMRP) imparts a high level of control on the polymerization of acrylic and vinylic esters, acrylic acid and acrylonitrile. However, each class of monomers appears to be controlled by one class of cobalt complexes. For example, the polymerization of acrylates and acrylic acid is mediated by cobalt porphyrin complexes while vinyl acetate (VAc) and acrylonitrile are efficiently controlled by bis(acetylacetonato)cobalt(II) (Co(acac)2). Therefore, a challenging issue in CMRP remains to broaden the range of monomers that can be controlled by the same cobalt complex. Recently, the controlled random copolymerization of butyl acrylate (BuA) with VAc was performed using the conventional V-70/Co(acac)2 CMRP system, but the homopolymerization of BuA remained uncontrolled. In this work, we used a new alkylcobalt(III) adduct to initiate and control the copolymerization of BuA with VAc. This achievement resulted in a significant improvement over the V-70/Co(acac)2 pair regarding the molecular weight control and the polydispersity indexes. Moreover, for the first time, the alkylcobalt(III) adduct was also efficient in controlling the homopolymerization of BuA and yielded low polydispersity PBuA even in the absence of VAc. These results indicate that Co(acac)2 is a versatile mediator for the CMRP of both unconjugated vinyl monomers (VAc, N-vinylpyrrolidone) and conjugated monomers such as acrylates. It gives access to copolymers that cannot be prepared by other controlled radical polymerization techniques

Poly(ionic liquid)-derived N-doped carbons with hierarchical porosity for lithium and sodium ion batteries

The performance of lithium and sodium ion batteries relies notably on the accessibility to carbon electrodes of controllable porous structure and chemical composition. This work reports a facile synthesis of well-defined porous N-doped carbons (NPCs) using a poly(ionic liquid) (PIL) as precursor, and graphene oxide (GO)-stabilized poly(methyl methacrylate) (PMMA) nanoparticles as sacrificial template. The GO-stabilized PMMA nanoparticles were first prepared and then decorated by a thin PIL coating before carbonization. The resulting NPCs reached a satisfactory specific surface area of up to 561 m2/g and a hierarchically meso- and macroporous structure while keeping a nitrogen content of 2.6 wt %. Such NPCs delivered a high reversible charge/discharge capacity of 1013 mA h/g over 200 cycles at 0.4 A/g for lithium ion batteries (LIBs), and showed a good capacity of 204 mA h/g over 100 cycles at 0.1 A/g for sodium ion batteries (SIBs).Comment: 14 pages, 9 figure

Design of mesoporous carbon fibers from a poly(acrylonitrile) based block copolymer by a simple templating compression moulding process

Mesoporous carbon fibers were prepared by controlled pyrolysis of poly(vinyl acetate)-b-poly(acrylonitrile) (PVAc-b-PAN) copolymer located inside a cylindrical nanoporous template. A melt-compression method was developed to help the penetration of the infusible copolymer inside the template without the use of any solvent that ensures the formation of completely filled fibers instead of nanotubes. The influence of the composition of the PVAc-b-PAN copolymer and the heating rate during pyrolysis on the porous morphology of the fibers was studied by transmission electron microscopy (TEM)

Atom transfer radical polymerization of MMA with a macromolecular ligand in a fluorinated solvent and in supercritical carbon dioxide

Macromolecular fluorinated ligands were prepared according to a three-step strategy that consists of the random copolymerization of heptadecafluorodecyl acrylate and 2-hydroxyethylacrylate, followed by the esterification of the pendant hydroxyl groups with acryloyl chloride and the Michael-type addition of tetraethyldiethylenetriamine onto the acrylic double bonds of the polymeric chains. These fluorinated macroligands were successfully used in the atom transfer radical polymerization of MMA catalyzed by a copper salt in a fluorinated solvent. The polymerization control was analyzed in relation to the copper salt, the initiator and the molecular weight and composition of the macroligand before being extended to the heterogeneous ATRP of MMA in scCO2

Failure of dams arranged in series or in complex

peer reviewedaudience: researcher, professional, studentA practical methodology has been developed for predicting flows generated by dam failures or malfunctions in a complex or a series of dams. A twofold approach is followed. First, the waves induced in the downstream reservoirs are computed, as well as hydrodynamic impacts induced on downstream dams and dikes are estimated. Second, the flood wave propagation and the inundation process are simulated in the downstream valley, accounting for possible dam collapse or breaching in cascade. Two complementary flow models are combined: a two-dimensional fully dynamic model and a simplified lumped model. At each stage, the methodology provides guidelines to select the most appropriate model for efficiently computing the induced flows. Both models handle parametric modeling of gradual dam breaching. The procedure also incorporates prediction of breach formation time and final width, as well as sensitivity analysis to compensate for the high uncertainties remaining in the estimation of breach parameters. The applicability of the modeling procedure is demonstrated for a case study involving a 70m-high gravity concrete dam located upstream of four other dams

Stimuli-responsive Magnetic Nanohybrids for Triggered Drug Release and Potential Tumor Treatment via Hyperthermia

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