Atomically Sharp Interface in an h-BN-epitaxial graphene van der Waals Heterostructure

International audienceStacking various two-dimensional atomic crystals is a feasible approach to creating unique multilayered van der Waals heterostructures with tailored properties. Herein for the first time, we present a controlled preparation of large-area h-BN/graphene heterostructures via a simple chemical deposition of h-BN layers on epitaxial graphene/SiC(0001). Van der Waals forces, which are responsible for the cohesion of the multilayer system, give rise to an abrupt interface without interdiffusion between graphene and h-BN, as shown by X-ray Photoemission Spectroscopy (XPS) and direct observation using scanning and High-Resolution Transmission Electron Microscopy (STEM/HRTEM). The electronic properties of graphene, such as the Dirac cone, remain intact and no significant charge transfer i.e. doping, is observed. These results are supported by Density Functional Theory (DFT) calculations. We demonstrate that the h-BN capped graphene allows the fabrication of vdW heterostructures without altering the electronic properties of graphene

Novel chemical process for preparing h-BN solid lubricant coatings on titanium-based substrates for high temperature tribological applications

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Mechanical properties of sol–gel coatings on polycarbonate: a review

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Recent Developments in Polymer‐Derived Ceramic Fibers (PDCFs): Preparation, Properties and Applications – A Review

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Correlation between structural features and mechanical properties of boron nitride fibres derived from alkylaminoborazines

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X-RAY STRUCTUREOF 1,2-DIBORAZINE-2,6-DICHLORO-4,4\6-TRI(DIISOPROPYLAMINO) TOLUENE SOLVATE

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Boron-based Ceramics: Design, Processing, and Properties

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THERMAL OLIGOMERIZATION OF UNSYMMETRICALLY B-TRISUBSTITUTED BORAZINES

International audienceThe B-alkylaminosubstituted borazines (NEt 2) 3 B 3 N 3 H 3 (1), (ΝΕ1 2) 2 (ΝΗΡ0Β 3 Ν 3 Η 3 (2), (NEt 2)(NHPr') 2 B 3 N 3 H 3 (3) and (NMe 2)(NHMe) 2 B 3 N 3 l-l3 (4) have been prepared and characterized by spectroscopic techniques. Their thermolyses at moderate temperature have been investigated in order to elucidate the effects of the nature of the B-alkylamino substituents on the resulting polyborazines backbone. Early stages of the degradations were accompanied by the elimination of primary and secondary amines for (2), (3) and (4). On the basis of 13 C NMR data, oligomerizations have been shown to occur mainly via the formation of direct interring B-N bonds rather than classical deamination with formation of-N(R)-bridges between borazine rings. This phenomenon should be related to the presence of dialkylamino substituents on the boron atoms

Non-Oxide Ceramic Thin Films Using the PDCs Approach

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Relevant insight of surface characterization techniques to study covalent grafting of a biopolymer to titanium implant and its acidic resistance

International audiencePeri-implant bacterial infections are the main cause of complications in dentistry. Our group has previously proposed the attachment of chitosan on titanium implants via a covalent bond to improve its antibacterial properties while maintaining its biocompatibility. A better knowledge of the coating preparation process allows a better understanding of the bioactive coating in biological conditions. In this work, several relevant characterization techniques were used to assess an implant device during its production phase and its resistance in natural media at different pH. The titanium surface was functionalized with 3-aminopropyltriethoxysilane (APTES) followed by grafting of an organic coupling agent; succinic anhydride, able to form two covalent links, with the substrate through a Ti-O-Si bond and the biopolymer through a peptide bond. Each step of the coating synthesis as well as the presence confirmation of the biopolymer on titanium after saliva immersion was followed by FTIR-ATR, SEM, EDS, 3D profilometry, XPS and ToF-SIMS analyses. Results allowed to highlight the efficiency of each step of the process, and to propose a mechanism occurring during the chitosan coating degradation in saliva media at pH 5 and at pH 3