Efficient microwave-assisted synthesis of glycerol monodecanoate

International audience; Solvent-free microwave-assisted synthesis was carried out to prepare 2,3-dihydroxypropyl decanoate, by esterification of decanoic acid in the presence of two distinct glycerol derivatives, glycidol, and glycerol carbonate, respectively. The process described is based on microwaves heating source with electrical power in the range of 200–400 W, involving stoichiometric proportions of decanoic acid and glycerol derivatives, and using catalytic amounts of TBAI used as organocatalyst. Conversion and selectivity rates of esterification reactions were monitored by 1H and 13C{1H} NMR spectroscopy. The predominantly formed ester, 2,3-dihydroxypropyl decanoate was fully chara…

Carvacrol affects interfacial, structural and transfer properties of chitosan coatings applied onto polyethylene

Different chitosan coating solutions were tested with the aim of investigating their adhesion and wettability onto polyethylene film to improve packaging performance and provide antimicrobial properties. Surface wetting kinetics was monitored by contact angle measurements. Addition of ethanol and carvacrol improved wettability and adhesion of the thin chitosan layer. Structure, water vapour, O2, CO2 and air permeabilities of self supported chitosan films and coated polyethylene were determined. The formation of a thin chitosan layer on polyethylene improved gas barrier properties decreasing the Permeability Coefficient for oxygen and carbon dioxide ( [Formula: see text] , [Formula: see text…

Stretched fibre based dispersion compensating module for ultra high-speed telecommunication systems

International audience; In this work, the potential efficiency of a low-loss, tunable second-and third-order dispersion compensating module based on a stretched optical fibre for ultra high-speed telecommunication systems is analysed. Experimental results at a repetition rate of 640 GHz show that precise dispersion compensation could be achieved in the range of +0.038 ps/nm by means of an 11.3 cm maximum stretching of a 48 m long dispersion compensating.

Polymer stain resistance: Prediction versus experiment

Synthesis of polybutadiene-polycaprolactone multi-blokcs based on hydroxyl telechelic polybutadiene. Composition and kinetic study

International audience

Organo-catalyzed synthesis of aliphatic polycarbonates in solvent-free conditions

A new efficient and expeditious route to the synthesis of aliphatic polycarbonates, in solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as a catalyst precursor, is described. The protocol consists of a two-step polymerization process involving the transesterification of dimethyl carbonate (DMC) with linear alkane diols and leading to high molecular weight homopolymers. The reaction went to completion quantitatively with the liberation of methanol as the only by-product. The in situ formation of N-heterocyclic carbene species resulting from BMIM-2-CO2 decarboxylation is suggested to be a key feature of the condensation process. The protocol was then …

Influence of a density mismatch on TMPTMA shells nonconcentricity

Some laser target designs require low-density organic foam shells to study fusion on the French high-power laser laser mega joule. Low-density trimethylolpropane trimethacrylate foam shells composed of C, H, and O, 2 mm diameter, 100-μm wall thickness, and 250 mg cm−3 density are synthesized by a microencapsulation technique using a droplet generator. These shells have to reach a sphericity higher than 99.9% and a nonconcentricity (NC) lower than 1%. The wall thickness variation is one of the most difficult specifications to meet. An important factor in reducing this defect is the density matching between the three phases of the emulsion at polymerization temperature. The influence of a den…

Etude des inclusions végétales dans les archéomatériaux argileux, par imprégnation de polymères

International audience; Cette application, en cours de perfectionnement, est destinée à l’étude de matériaux archéologiques contenant deséléments végétaux, comme des poteries ou des matériaux de construction. Elle devrait être utile aux archéobotanistes et leur fournir une nouvelle source de matériel à exploiter. Plus largement, cette technique est destinée à fournir de nouvelles sources d’étude pour la technologie des matériaux, la gestion des matières premières et le traitement des produits alimentaires.

Chain-extending of Hydroxytelechelic Polybutadiene: Synthesis and Characterization

Extension of hydroxytelechelic polybutadiene oligomers ( 3200 g/mol) is performed in mild conditions, in order to avoid backbone modifications, using succinic anhydride or methylenedicyclohexyl diisocyanate. The two routes present significative extension of the initial oligomers. Extension through the anhydride route, in the presence of DCC and DMAP, leads to new hydroxytelechelic oligomers ( 8000 g/mol). Extension through the diisocyanate route, catalyzed by DBTL at 65°C leads to hydroxytelechelic oligomers of higher average molecular weight ( 20000 g/mol). New materials are characterized by FTIR/1H-NMR and changes in their Tg according to , are discussed. The influence of reaction time on…

New approach for synthesis of poly(ethylglyoxylate) using Maghnite-H + , an Algerian proton exchanged montmorillonite clay, as an eco-catalyst

International audience; In this works, we have explored a new method for a green synthesis of poly(ethylglyoxylate) (PEtG). This method consists on using a montmorillonite clay called Maghnite-H+ as an eco-catalyst to replace triethylamine which is toxic. Cationic polymerization experiments are performed in bulk conditions at three temperatures (-40 degrees C, 25 degrees C, 80 degrees C) and in THF solutions at room temperature (25 degrees C). At 25 degrees C, an optimum ratio of 5 wt% of catalyst leads to molar masses up to 22000 g/mol in THF solutions. Polymerizations in bulk conditions lead to slightly lower masses than experiments conducted in THF solutions. However, bulk polymerization…

Étude d'inclusions végétales dans des tessons de poterie ou des matériaux de construction

Vegetal inclusions embedded in clayey materials (cob, ceramic, mudbrick) are investigated by using impregnation of the porous material with a fluorescent polymer. The micro-casting of the porosity is exploited by following two ways. Sections of the treated samples are examined under UV-light, showing vegetal structures amenable to a botanical identification and quantification. Moreover, micro-casts embedded in the mineral matrix have been successfully sorted. This new application is a tool to study archaeological samples previously not amenable to the work of archaeobotanists and to expand their field of investigation.

Series of charge transfer complexes obtained as crystals in a confined environment

A series of charge transfer complexes (CTCs) were successfully formed by solvent free processing techniques, using the 1,2,4,5-tetracyano benzene (TCNB) as πA molecule and a series of p-dihydroquinones (H2Qs) as πD counterparts. Additionally to the classical co-evaporation techniques, we obtained CTCs in less than an hour, in a very simple confined environment, between two 100 μm – spaced glass plates. A systematical study by Raman spectroscopy on crystals highlighted the CTCs formation. Moreover, three new crystalline structures were obtained, namely TCNB-H2Q that crystallizes in columns connected to each other by H-bonds, while with the methoxy- and dimethoxy-H2Qs the CTC forms crystals w…

Structure and thermal properties of a chitosan coated polyethylene bilayer film

The thermal and the structural properties of chitosan coated polyethylene (PE) films were studied. The coating process did not significantly influence the thermal stability and the PE surface structure and/or composition of the polyolefin. Dehydration temperature of chitosan films reflected the strength of water/acetic acid/chitosan chains interactions. Glycerol, used as a plasticizer, formed new hydrophilic centres in the film matrix. Moreover it was better integrated in the CSEGLY than in CSAGLY network. Besides, the addition of a plasticizer in the chitosan films decreased the film degradation temperature. There were two main steps for the PE chitosan coated films degradation. The first …

Use of new hydroxytelechelic cis-1,4-polyisoprene (HTPI) in the synthesis of polyurethanes (PUs): Influence of isocyanate and chain extender natureand their equivalent ratios on the mechanical and thermal properties of PUs

AbstractNew segmented polyurethanes (thermoplastic-elastomers) based on previously described hydroxytelechelic cis-1,4-polyisoprene (HTPI), miscellaneous isocyanates and chain extenders at various equivalent ratios were prepared by the classical one-shot method. The influence of the nature of isocyanate and chain extender, as well as their equivalent ratios, on the mechanical and thermal materials behavior was investigated. Thus, a comparative assessment of material properties was performed. Microphase separation of hard and soft segments was observed by DMTA, DSC and AFM. Moreover, according to Thermogravimetric Analysis (TGA), linear relationships depending on the isocyanate and chain ext…

In VitroRelease of Local Anaesthetic and Anti-Inflammatory Drugs from Crosslinked Collagen Based Device

The drug delivery systems that are the object of this article take the form of a hydrophilic matrix (collagen or crosslinked collagen) containing a drug. These devices can be used as The model active agents, were chosen from the range of local anaesthetics (lidocaine hydrochloride), anti-inflammatory (diclofenac sodium salt) and antioxydant (caffeic acid). Whatever the drug affinity for water, in the first time of the experiments, the release appears to be systematically delayed when the matrix is crosslinked. For lidocaine hydrochloride based systems, as the amount of drug increases in the matrix, the high gap concentration between the matrix and the buffer solution promote the diffusion a…

Characterizations of Thermoplastic Block Elastomers Based on Polybutadiene and ε -Caprolactone

A broad series of tri- and multiblock copolymers based on linear and branched oligomers of polybutadiene as central blocks and polycaprolactone (PCL) as block extremities are characterized by SEC, DSC, DMA, Dynamical Rheology and DRX. DSC analyses reveal phase separation between the two amorphous PB and PCL phases. By thermal analysis, the glass transition temperature of PCL is only detected for materials containing at least 80% w/w of PCL. This is attributed to the small length of the polyester blocks for copolymers containing less than 80% w/w of PCL. The increase of fusion heat with increasing PCL content in the copolymers is correlated to the greater ability of PCL chains to rearrange a…

One step grafting of monomethoxy poly(ethylenglycol) during synthesis of maghemite nanoparticles in aqueous medium

Abstract Grafting of silanated monomethoxy poly(ethylene glycol) (m-PEG) onto maghemite nanoparticles surface in aqueous medium through one step procedure was investigated. The major characteristic of this work is that the grafting of m-PEG was produced during the synthesis of maghemite nanoparticles. The maghemite nanoparticles were characterized by photon correlation spectroscopy (PCS), zeta potential measurement, X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), and X-ray photoelectron spectroscopy (XPS). The spinel structure of maghemite nanoparticles was verified and successful grafting of m-PEG was evid…

1-n-Butyl-3-methylimidazolium-2-carboxylate: a versatile precatalyst for the ring-opening polymerization of ε-caprolactone and rac-lactide under solvent-free conditions

The ring-opening polymerization of ε-caprolactone (ε-CL) and rac-lactide (rac-LA) under solvent-free conditions and using 1-n-butyl-3-methylimidazolium-2-carboxylate (BMIM-2-CO2) as precatalyst is described. Linear and star-branched polyesters were synthesized by successive use of benzyl alcohol, ethylene glycol, glycerol and pentaerythritol as initiator alcohols, and the products were fully characterized by 1H and 13C{1H} NMR spectroscopy, gel permeation chromatography (GPC), and differential scanning calorimetry (DSC). BMIM-2-CO2 acts as an N-heterocyclic carbene precursor, resulting from in situ decarboxylation, either by heating under vacuo (method A) or by addition of NaBPh4 (method B)…

CCDC 1994293: Experimental Crystal Structure Determination

Related Article: Ali Sanda Bawa, Rita Meunier-Prest, Yoann Rousselin, Jean-Pierre Couvercelle, Christine Stern, Bernard Malézieux, Marcel Bouvet|2021|CrystEngComm|23|6418|doi:10.1039/D1CE00929J

CCDC 2063384: Experimental Crystal Structure Determination

Related Article: Ali Sanda Bawa, Rita Meunier-Prest, Yoann Rousselin, Jean-Pierre Couvercelle, Christine Stern, Bernard Malézieux, Marcel Bouvet|2021|CrystEngComm|23|6418|doi:10.1039/D1CE00929J

CCDC 1994294: Experimental Crystal Structure Determination

Related Article: Ali Sanda Bawa, Rita Meunier-Prest, Yoann Rousselin, Jean-Pierre Couvercelle, Christine Stern, Bernard Malézieux, Marcel Bouvet|2021|CrystEngComm|23|6418|doi:10.1039/D1CE00929J