Novel Ionic Conducting Composite Membrane Based on Polymerizable Ionic Liquids.

In this work, the design and characterization of new supported ionic liquid membranes, as medium-temperature polymer electrolyte membranes for fuel-cell application, are described. These membranes were elaborated by the impregnation of porous polyimide Matrimid® with different synthesized protic ionic liquids containing polymerizable vinyl, allyl, or methacrylate groups. The ionic liquid polymerization was optimized in terms of the nature of the used (photo)initiator, its quantity, and reaction duration. The mechanical and thermal properties, as well as the proton conductivities of the supported ionic liquid membranes were analyzed in dynamic and static modes, as a function of the chemical structure of the protic ionic liquid. The obtained membranes were found to be flexible with Young's modulus and elongation at break values were equal to 1371 MPa and 271%, respectively. Besides, these membranes exhibited high thermal stability with initial decomposition temperatures > 300 °C. In addition, the resulting supported membranes possessed good proton conductivity over a wide temperature range (from 30 to 150 °C). For example, the three-component Matrimid®/vinylimidazolium/polyvinylimidazolium trifluoromethane sulfonate membrane showed the highest proton conductivity-~5 × 10-2 mS/cm and ~0.1 mS/cm at 100 °C and 150 °C, respectively. This result makes the obtained membranes attractive for medium-temperature fuel-cell application.

Hydrophobization of chitosan films by surface grafting with fluorinated polymer brushes.

Chitosan with its surface-properties and biodegradability is a promising biomaterial for green packaging applications. Till now, this application is still limited due to chitosan high sensitivity to water. Some existing studies deal with the incorporation of hydrophobic additives to enhance water-proof performances of chitosan films. As these additives may impair the film properties, our study focuses on chitosan efficient hydrophobization by means of simple and successful surface grafting reactions. Chitosan films prepared by solvent casting were modified by means of surface-initiated activators regenerated by electron transfer atom radical polymerization (SI-ARGET-ATRP) of 2-hydroxyethyl methacrylate (HEMA) followed by esterification reaction with fluorinated acyl compound. X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) highlighted the surface chemical changes after each step. Surface properties were investigated by contact angle measurements and surface energy calculations. Hydrophobic surfaces with low surface energy and good water-repellent properties were obtained using a simple handling polymerization procedure. This is the first study in applying ARGET ATRP to prepare hydrophobic biopolymer films offering potential applications in packaging.

Synthesis of 3-amino-thiochromanes from 4-benzyl 2-thiazolines, via an unprecedented intramolecular electrophilic aromatic substitution.

A one-pot synthesis of various N-substituted 3-amino-thiochromanes from 4-benzyl-2-methyl thiazoline via a thiazolinium salt is described. The obtained 3-amino-thiochromanes are enantiopure, as their precursors derive from chiral 2-aminoalcohols. The reaction involves the formation of a disulfide, which subsequently takes part in an unprecedented intramolecular electrophilic aromatic substitution.

Synthesis and properties of thiazoline based ionic liquids derived from the chiral pool.

A novel class of chiral ionic liquids derived from amino alcohols is prepared in multi-gram scale. Their potential in chiral recognition is shown in a preliminary example with racemic Mosher's acid salt.

Gas-Phase Generation and Photoelectron Spectra of Reactive Unsubstituted Cycloalkenethiones.

The flash vacuum thermolysis of cycloalkenyl allyl sulfides, potential precursors of unsubstituted cycloalkenethiones, has been investigated by photoelectron spectroscopy. This technique allowed us to characterize in the gas phase very reactive species of this series, the conjugated and nonconjugated cyclopentene and cyclohexenethiones, and to compare the reactivity of these compounds. The assignment of the PE spectra is supported by electronic structure calculations, particularly by the HF method at the MP2 level and the density functional theory (DFT) using the B3LYP and BP86 functionals with the 6-311G(d, p) basis set. Copyright 2001 Academic Press.