Christine Gérardin-Charbonnier

A supramolecular hydrogel based on an original pseudopeptidic catanionic surfactant

A novel low-molecular weight gelator based on a mixture of a cationic pseudopeptidic surfactant and lauric acid (1/3), at basic pH, is reported. The gelling properties of this system have been investigated by Infra-Red spectroscopy (FT-IR), Scanning and Transmission Electron Microscopies (SEM, TEM), and Small Angle X-ray Scattering (SAXS).

Réactivité des acides 2-perfluoroalkyléthanoı̈ques: préparation de tensioactifs originaux et application à la formulation d'émulsions–gels

Abstract 2H, 2H-perfluoroalkylethanoic acids give, under mild conditions, in the presence of alcoholic potassium hydroxide, corresponding enol ethers or ketals in very good yield. The reduction of the acid function of these derivatives and the aminolysis of the corresponding esters lead to relatively hydrophobic surfactants. These compounds have been tested to determine if they give stable gel–emulsions from fluorocarbons.

Etude du réarrangement de Beckmann des sels d'OTDP des oximes de cétones aromatiques et applications en synthèse

Abstract bdBeckmann rearrangement of OTDP salts of oximes of aromatic ketones and synthetic applications . Reaction between tris(dimethylamino)-phosphine, carbon tetrachloride and oximes of ketones leads to the corresponding Oximoxy-Tris-(Dimethylamino)-Phosphonium salts (OTDP salts), which are isolated in the form of hexafluorophosphates. These salts are solid and stable except if they are completely dehydrated. Their solutions, in non polar solvents like CHCl 3 , give Beckmann rearrangement at room temperature. The kinetics and mechanism have been studied by NMR. We have defined the conditions of trapping of the cationic intermediates formed in the rearrangement, leading to an effective synthesis of amidines and an access to a glycoside structure using the hemiacetalic hydroxyl group of sugar as nucleophile.

An Improved Synthesis of [btilde]-Perfluoroalkylated Analogues of [btilde]-Alanine

Abstract A very simple route to perfluoroalkylated analogues of [btilde]-alanine is proposed via a reaction between amines or sodium azide and 3-perfluoroalkyl-3-fluoro-prop-2-enoate followed by hydrogenation.

Tartaric acid catalyzed furfurylation of beech wood

European beech (Fagus sylvatica L.) is a major tree species of European forest which is underexploited because of its low dimensional stability and durability. Similarly to what has been developed with radiata pine, furfurylation might be the answer to optimize the utilization of local beech wood. Beech wood furfurylation process was studied using five different catalysts: maleic anhydride, maleic acid, citric acid, itaconic acid, and tartaric acid. Optimization of the furfurylation process was investigated for different catalyst and furfuryl alcohol (FA) contents, and different duration of polymerization. The following properties were studied: weight percent gain (WPG), leachability, anti-swelling efficiency (ASE), wettability, modulus of elasticity, modulus of rupture, Brinell hardness, and decay durability. Tartaric acid, never investigated up to now, was retained as catalyst to perform furfurylation due to its efficacy compared to other catalysts and its novelty. Wood modification with FA and tartaric acid as catalyst led to samples with high WPG even after leaching, improved ASE, and lower wettability with water. Increasing the polymerization duration increased the fixation of FA in treated wood. Most of all, treatment gave a significant improvement in mechanical properties and resistance to wood decaying fungi.

Hydrogel-based boron salt formulations for wood preservation

Mixing boron with two thermoreversible hydrogels, obtained from an amphiphilic tripeptide and a carbamate derivative of glycerol, respectively, allows the formation of a supramolecular network that incorporates boron and significant amounts of water upon gelification of the solution when the temperature decreases. Hydrogels obtained from these gelators were impregnated in pine sapwood blocks using vacuum pressure treatment and subjected to leaching. Results indicated that incorporation of boron salts in the hydrogel network effectively protected the wood from degradation caused by the brown rot fungus Poria placenta and from attack by termites also even after leaching. It is believed that these hydrogels fill the tracheid cell walls and lumens, limiting the leachability of boron salts when the wood is humidified.