Ultrasound exfoliation of inorganic analogues of graphene

High-intensity ultrasound exfoliation of a bulk-layered material is an attractive route for large-scale preparation of monolayers. The monolayer slices could potentially be prepared with a high yield (up to 100%) in a few minutes. Exfoliation of natural minerals (such as tungstenite and molybdenite) or bulk synthetic materials (including hexagonal boron nitride (h-BN), hexagonal boron carbon nitride (h-BCN), and graphitic carbon nitride (g-C(3)N(4))) in liquids leads to the breakdown of the 3D graphitic structure into a 2D structure; the efficiency of this process is highly dependent upon the physical effects of the ultrasound. Atomic force microscopy (AFM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) were employed to verify the quality of the exfoliation. Herein, this new method of exfoliation with ultrasound assistance for application to mono- and bilayered materials in hydrophobic and hydrophilic environments is presented

Influence of ionic liquid-modified LDH on microwave-assisted polymerization of ε-caprolactone

International audienceThe study reported herein describes multifunctional effect of layered double hydroxide (LDH) modified with phosphonium-based ionic liquids (IL) containing phosphinate, carboxylate and phosphate anions on progress of ring-opening polymerization of ε-caprolactone under microwave irradiation. The extent of IL-modification had a crucial effect on the exfoliation of LDH. The non-modified LDH was able to catalyse the ring-opening polymerization of ε-caprolactone with polymer yield 89% but provided only micro-composite material. On the contrary, LDH with intercalated IL-anions promoted exfoliation of LDH after only 3 min of microwave irradiation. The developed process is fast, environmentally-friendly (solvent-free) and adaptable to various polymer matrices, since a broad variety of IL-anions might be applied

Polyhedral oligomeric silsesquioxane-supported ionic liquid for designing nanostructured hybrid organic-inorganic networks

International audienc

Ionic Liquids as Delaminating Agents of Layered Double Hydroxide during In-Situ Synthesis of Poly (Butylene Adipate-<i>co</i>-Terephthalate) Nanocomposites

Currently, highly demanded biodegradable or bio-sourced plastics exhibit inherent drawbacks due to their limited processability and end-use properties (barrier, mechanical, etc.). To overcome all of these shortcomings, the incorporation of lamellar inorganic particles, such as layered double hydroxides (LDH) seems to be appropriate. However, LDH delamination and homogenous dispersion in a polymer matrix without use of harmful solvents, remains a challenging issue, which explains why LDH-based polymer nanocomposites have not been scaled-up yet. In this work, LDH with intercalated ionic liquid (IL) anions were synthesized by a direct co-precipitation method in the presence of phosphonium IL and subsequently used as functional nanofillers for in-situ preparation of poly (butylene adipate-co-terephthalate) (PBAT) nanocomposites. The intercalated IL-anions promoted LDH swelling in monomers and LDH delamination during the course of in-situ polycondensation, which led to the production of PBAT/LDH nanocomposites with intercalated and exfoliated morphology containing well-dispersed LDH nanoplatelets. The prepared nanocomposite films showed improved water vapor permeability and mechanical properties and slightly increased crystallization degree and therefore can be considered excellent candidates for food packaging applications

Study of Interactions between Titanium Dioxide Coating and Wood Cell Wall Ultrastructure

Titanium dioxide (TiO2) is used as a UV light absorber to protect wood matter from photodegradation. In this paper, interactions between wood and TiO2 coating are studied, and the efficiency of the coating is evaluated. For the experiments, two wood species were chosen: beech (Fagus sylvatica) and pine (Pinus sylvestris). Molecular and physical modifications in coated and uncoated wood exposed to UV radiation were investigated with Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) and transmission electron microscopy (TEM). UV-VIS spectroscopy was used to describe the absorption of UV light by the TiO2 planar particles chosen for the experiment. It was demonstrated that TiO2 coating protects wood against photodegradation to a limited extent. TEM micrographs showed fissures in the wood matter around clusters of TiO2 particles in beech wood

Iron–Bismuth Halido Compounds: Molecules, Clusters, and Polymers

The pentamethylcyclopentadienyl substituted iron–bismuth halides [Bi­{FeCp*­(CO)₂}­X₂] [X = Cl (<b>1</b>), Br (<b>2</b>), I (<b>3</b>); Cp* = η⁵-C₅Me₅] were synthesized starting from [FeCp*­(CO)₂]₂ and BiX₃ (X = Cl, Br), followed by halogen exchange reaction with KI in case of <b>3</b>. From a reaction mixture of [FeCp*­(CO)₂]₂ with BiCl₃ in CH₂Cl₂ to which CH₃CN had been added, a novel coordination polymer of the formula [FeCp*­(CO)₂(CH₃CN)]_2<i>n</i>[Bi₄Cl₁₄]_<i>n</i> (<b>4</b>) was isolated. The change of the molar ratio from 1:1 to 1:2 in the reaction of [FeCp*­(CO)₂]₂ with BiBr₃ afforded the novel ionic complex [{FeCp*­(CO)₂Br]₂[Bi₆Br₂₂{FeCp*­(CO)₂}]·CH₂Cl₂ (<b>5</b>·CH₂Cl₂). It is demonstrated that treatment of [FeCp*­(CO)₂X] (X = Cl, Br) with BiCl₃ and BiBr₃, respectively, is a more convenient route to synthesize the new halido bismuthates <b>4</b> and <b>5</b>