Antifriction and Antiwear Properties of an Ionic Liquid with Fluorine-Containing Anion Used as Lubricant Additive.

Tribological behavior of trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl) imide [P66614][NTf2] ionic liquid (IL) used as additive in a diester oil at concentrations of 0.25, 0.5 and 1 wt% was studied in this research. The IL solubility in the base oil was measured using the inductively coupled plasma mass spectrometry (ICP-MS) technique, and corrosion analysis was done at room temperature at relative humidity of 49–77%. Tribological tests were conducted for 30 min at room temperature, 15 Hz frequency, 4 mm of stroke length, a load of 80 N (corresponding to 2 GPa of maximum contact pressure) and relative humidity of 35–53%. Friction coefficient was recorded during tests, and the wear scar was measured by confocal microscopy. Worn surface was also analyzed by SEM, EDS and XPS. Results showed that a saturated solution of [P66614][NTf2] in the base oil contains about 30 wt% of IL and corrosion activity for the highest concentration of IL (1 wt%) was not found after a 20-day test. Although the base oil and the mixtures had similar friction behavior, only the 1 wt% sample exhibited slightly lower wear volume than the base oil. SEM images exhibited similar wear track width (707–796 µm) and wear mechanism (adhesive) for all samples tested. In addition, the EDS spectra only showed the elements present in the steel. Finally, the XPS measurements could not detect differences regarding iron chemical state among the samples, which is consistent with the tribological behavior obtained

Yttrium Complexes Supported by Linked Bis(amide) Ligand: Synthesis, Structure and Catalytic Activity in the Ring-Opening Polymerization of Cyclic Esters

International audienc

Ytterbium(III) Complexes Coordinated by Dianionic 1,4-Diazabutadiene Ligands

International audienc

Iminophosphorane Neodymium(III) Complexes As Efficient Initiators for Lactide Polymerization

Bis(iminophosphoranyl)methanide ({CH(PPh(2)NR)}(-), R = iPr or Ph) neodymium(III) complexes were prepared from NdI(3)(THF)(3.5). The steric bulk of the ligand controlled the stoichiometry of the resulting complexes. Thus, three new complexes, bearing one or two ancillary ligands, were prepared and characterized using various spectroscopic techniques and by single-Crystal X-ray diffraction. Reaction of the heteroleptic neodymium iodide complexes with amido groups yielded viable initiators for the ring-opening polymerization of lactide. The polymerizations were conducted using either the heteroleptic neodymium amido complexes or the in situ generated alkoxide complexes. Using such conditions, the neodymium complexes showed very fast and well-controlled polymerizations, with complete conversion being obtained in only a few minutes and yielding polylactide with controlled molecular weight and narrow polydispersity index. An initiating system comprising a rare neodymium-alkyl-carbene complex [Nd{C(PPh(2)NiPr)(2)}{CH(PPh(2)NiPr)(2)}] and externally added iPrOH was also an unexpected catalyst for the ROP of lactide

Anilidopyridyl-pyrrolide and -indolide Group 3 Metal Complexes: Highly Active Initiators for the Ring-Opening Polymerization of rac-Lactide

Three new group 3 metal complexes, bearing anilidopyridyl-pyrrolide (L1) and anilidopyridyl-indolide (L2) as dianionic tridentate ligands, with the general formula LMN- (SiHMe2)2 were synthesized (complex 1, M = Y, L = L1; complex 2, M = Sc, L = L1; complex 3, M = Y, L = L2). All complexes were fully characterized and tested as initiators for the ROPs of rac-lactide. The yttrium complexes 1 and 3 resulted in highly active catalysts (TOF up to 104 mollactide molY −1 h−1), whereas the scandium complex showed moderate activities. This class of catalysts allowed a good control of the macromolecular architecture of the polymer, namely, the nature of end groups, the molecular weights, and their distribution. Moreover, the obtained PLAs showed Pr values in the range of 0.57−0.84, depending on the nature of the initiator and solvent. Well-controlled and rapid ROPs of rac-lactide were obtained in the solvent-free polymerizations at 130 °C as well, suggesting that complexes 1−3 are stable at high temperature. Finally, in the presence of 2-propanol, complex 1 promoted the immortal ROP of rac-lactide, showing a remarkable TOF of 3.5 × 104 mollactide molY −1 h−1