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Two known imido vanadium (V) trichloride complexes [Cl3V=N-C6H3-2,6-Me2] (1) and [Cl3V=N-C6H3-2,6-iPr2] (2), both of which have escaped testing as ethylene polymerization catalyst precursors, were synthesized and their capacity to polymerize ethylene in the presence of the co-catalyst MAO (methylaluminoxane) (Al:V ratio: 1000:1) at 10 oC is reported. The resulting polymers, from both pre-catalysts, have molecular weights exceeding 1-2 million g/mol as suggested by the insolubility at high temperature and rheological measurements. According to the rheological and DSC annealing characterizations the synthesized UHMWPE from both 1 and 2 show features of a high degree of disentanglement.

Two known imido vanadium (V) trichloride complexes [Cl3V=N-C6H3-2,6-Me2] (1) and [Cl3V=N-C6H3-2,6-iPr2] (2), both of which have escaped testing as ethylene polymerization catalyst precursors, were synthesized and their capacity to polymerize ethylene in the presence of the co-catalyst MAO (methylaluminoxane) (Al:V ratio: 1000:1) at 10 oC is reported. The resulting polymers, from both pre-catalysts, have molecular weights exceeding 1-2 million g/mol as suggested by the insolubility at high temperature and rheological measurements. According to the rheological and DSC annealing characterizations the synthesized UHMWPE from both 1 and 2 show features of a high degree of disentanglement.

Two known imido vanadium (V) trichloride complexes [Cl3V=N-C6H3-2,6-Me2] (1) and [Cl3V=N-C6H3-2,6-iPr2] (2), both of which have escaped testing as ethylene polymerization catalyst precursors, were synthesized and their capacity to polymerize ethylene in the presence of the co-catalyst MAO (methylaluminoxane) (Al:V ratio: 1000:1) at 10 oC is reported. The resulting polymers, from both pre-catalysts, have molecular weights exceeding 1-2 million g/mol as suggested by the insolubility at high temperature and rheological measurements. According to the rheological and DSC annealing characterizations the synthesized UHMWPE from both 1 and 2 show features of a high degree of disentanglement.

International audience; Ring-opening metathesis polymerization, or ROMP, has been known in the world of polymers as a success story. With its discovery in the middle of the 20th century, the study and understanding of this reaction led to its adoption in a multitude of areas in both academic and industrial domains. However, with the general shift towards hybrid materials and better material integration, surface-initiated polymerization (SIP) has been an area of great interest that ROMP has only tapped into at the very end of the 20th century. With this point in mind, we demonstrate another pathway towards SIP using the si-ROMP approach to form block-copolymers of poly(ethylene-oxide)-poly(norbornene) (PEO-PNB) brushes on particles of titania. In this study, particle modification was first performed and studied, which was then applied towards coating larger, curved tubes to assess their ability for surface modification. In the case of particles, each step was analyzed by XPS to ensure that the expected elements appeared. TGA was then implemented to determine the general grafting density of the PEO chains on the surface, which was found to be 2.7 molecules per nm(2). TGA could also determine the degree of polymerization (DP) of the polynorbornene chain, which was 12 500. Finally, SEM was used to image the final products, both film formation using particles, and after use of these particles as a surface coating to cover larger surface areas for surface modification. The functionalized titania particles are determined to be an interesting candidate material for a "seed" layer, which can be used for larger surface modification.

A wide set of norbornene-derived polymers with a diversity in backbone and side chain structures has been prepared based on norbornene building blocks that also include a thiolactone group. For this purpose, two thiolactone monomers with differently substituted norbornene moieties were synthesized and their reactivity compared using three different polymerization strategies. First, their potential for amine-thiol-ene polymerization was evaluated using different amines, solvents and initiator concentrations in order to screen their influence on the molecular weight and glass transition temperature. Free radical (co-)polymerization and ring-opening metathesis polymerization were also applied and the obtained polymers were submitted to post-polymerization modification. The results showed that only the monomer 5-norbornenemethyl thiolactone carbamate results in polymer formation under the tested conditions. The obtained compounds were characterized by SEC, TGA, DSC and NMR.

Long, multifunctional sequence-defined oligomers were obtairred on solid support from a protecting-group-free two-step iterative protocol, based on the inherent reactivity of a readily available molecule containing an isocyanate and a thiolactone. Aminolysis of the latter entity with an amino alcohol liberates a thiol that reacts with an acrylate or acrylamide, present in the same medium. Subsequently, a new thiolactone can be reinstated by means of an alpha-isocyanato-gamma-thiolactone. Different acrylic compounds were used to incorporate diverse functionalities in the oligomers, which were built up to the level of decanters. The reaction conditions were closely monitored in order to fine-tune the applied strategy as well as facilitate the translation to an automated protocol.

A new top-down approach to generate stable nanoscale films via catalyst induced cross-linking (CIC) is demonstrated. Polymers with various compositions and bearing pendent norbornene groups (defined as macrocross-linkers) are initially spin-coated onto substrates to form nanometre-thick films; when the films are brought into contact with a catalyst solution, ring-opening metathesis polymerization (ROMP)-mediated cross-linking efficiently occurs to lock the film into place. CIC provides a new paradigm for the fabrication of stable nanoscale films and provides an alternative to traditional methods that use external stimuli (e.g., heat or light) to trigger film cross-linking. The process requires short cross-linking times (

International audience; In this paper, we describe a simple and powerful way to synthesize antibacterial biomaterials with applications as implants in orthopedic surgery. Such implants are obtained by covalently grafting onto the Ti90A16 V4 alloy surface with vancomycin-functionalized nanoparticles. Nanoparticles were produced by ring-opening metathesis polymerization of alpha-norbornenyl-omega-vancomycin poly(ethylene oxide) macromonomers. Vancomycin is an interesting candidate because of its use in the field of implant associated infection as it is a glycopeptide which acts on bacterial walls. As a consequence, vancomycin does not need to be released for it to be active. In the first part of this paper, the synthesis and the complete characterization of these materials are described. In a second part, the in vitro antibacterial behavior is analyzed and discussed.

A series of bis(trifluoromethylsulfonyl)amide based "polymeric ionic liquids" (PILs) as high molecular mass analogues of the corresponding imidazolium, ammonium and pyrrolidinium ionic liquids (ILs) was synthesized with high purity and fully characterized including electrochemical properties. The PILs differed by the nature of the cation, the quantity of the ionic centers in each monomer repeating unit, and the alkyl length of the spacer. Two novel ionic liquid like monomers (ILMs), namely 1,3-bis(N,N,N-trimethylammonium)-2-propylmethacrylate bis(trifluoromethylsulfonyl) amide (ILM-2) and N-[(2-methacryloyloxy)-ethyl]-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide (ILM-4) were synthesized and characterized. Optimal conditions for the free-radical polymerization of the ILMs were identified for the first time. It was demonstrated that, among the tested organic solvents, 1-methyl-3-ethylimidazolium bis(trifluoromethylsulfonyl)amide IL was the best reaction medium in terms of the achievement of high polymer yields and molecular masses. For the first time, the influence of the residual monomer presence inside the PIL film on the resultant conductivity was clearly shown. The impact of the molecular mass of the PILs on the ionic conductivity was firstly studied as well. Finally, the copolymerization of ILMs with poly(ethylene glycol)dimethacrylate (PEGDM) was carried out yielding tight elastic films with the highest conductivity equal to 3.2 x 10(-6) S/cm at 25 degrees C. (C) 2011 Elsevier Ltd. All rights

In this study, amphiphilic polyoxanorbornene with different alkyl and aromatic phosphonium side chains was synthesized. The biological activities of these polymers were determined by the minimal inhibitory concentration (MIC) against E. coli, S. aureus, M. tuberculosis and the yeast C. albicans, and cytotoxicity studies on red blood cells were performed. A series of polymers with different alkyl and aromatic substituents (methyl, ethyl, tripropyl, tert-butyl, phenyl, and tris 4-methoxyphenyl) and two types different molecular weight, 3000 g mol(-1) and 10 000 g mol(-1), were prepared. It was observed that the biological activity of the polymers with aromatic group substituents had an MIC of 16, 8, 64 and 128 mu g mL(-1) against E. coli, S. aureus, M. tuberculosis and C. albicans, respectively, while those with nonaromatic carbons had a higher MIC compared to those with aromatic carbons. The aromaticity of the repeat unit had impressive effects on hemolytic activities as well. Zeta potential measurements of E. coli incubated with active and inactive polymer concentration revealed a relationship between the MIC and membrane surface charge density. Polymers bearing aromatic groups killed the bacteria with widespread damage after the polymers, holding the threshold concentration, were added to the bacteria., Scientific and Technological Research Council of Turkey (TÜBİTAK); COST Action CM1302 SIPs

International audience; We report the synthesis of acid responsive polymeric nanoparticles (NPs) consisting of a polymerhistone deacetylase inhibitor conjugate. An innovative aspect of this drug delivery particle lies in the NP conjugation of a histone deacetylase (HDAC) inhibitor, CI-994 (Tacedinaline), introduced with a clickable acid-responsive prodrug during monomer synthesis, prior to polymerization. Another novelty lies in the selected norbornene (NB)-polyethylene oxide (PEO) macromonomer allowing standardization of the polymerization process by Ring-Opening Metathesis Polymerization (ROMP) and functionalization through azide-allcyne click chemistry. Herein we demonstrate that the synthesized polymer gave 300 nm core-shell spherical nanoparticles with low dispersity (0.04), high water dispersability thanks to the PEO shell and well controlled HDAC inhibitor prodrug loading. Bioluminescence Resonance Energy Transfer (BRET) assay in living cells and viability experiments demonstrated efficient cellular internalization without additional chemistry, drug release inside cells with restoration of the HDAC inhibition and induction of apoptosis. Such NPs should minimize drug release in vivo during blood circulation and trigger intracellular delivery after endocytosis, holding promises for improved efficacy of this class of epigenetic inhibitors. This standardized synthesis paves the way for multifunctional nanoparticles synthesis.

This review aims at guiding both new and established researchers in the field of self-healing by providing a clear overview of the fifteen most important chemistries used in autonomous external self-healing systems until today, together with their healing potential for different matrix materials and types of mechanical damage. The described self-healing systems require no manual intervention or additional stimulus for the self-healing event to take place (autonomous) and utilize added healing agents to repair the damage (external). A range of recent developments is discussed with indication of their strengths and weaknesses. An attempt is also made to demonstrate the research opportunities that are still available for each described system and to find the areas that require further elaboration. As such, this review can help to point the reader in the directions these self-healing materials could follow in the future.

Keywords: Diels-alder-reaction ; opening metathesis polymerization ; acid-catalyzed ; hydrolysis ; lithium aluminum-hydride ; soybean cyst nematode ; diastereoselective bis-hydroxylation ; thromboxane-a2 receptor ; antagonists ; enantioselective total synthesis ; wagner-meerwein ; rearrangements ; platelet-activating-factor Note: Univ Lausanne, Chim Sect, BCH, CH-1015 Lausanne, Switzerland. Ecole Super Phys & Chim Ind, Dept Chim Organ, F-75005 Paris 5, France. Univ Complutense Madrid, Fac Quim, Dept Quim Organ 1, E-28040 Madrid, Spain. Reference LGSA-ARTICLE-1999-014doi:10.1016/S0040-4020(99)00845-5 Record created on 2005-11-09, modified on 2017-05-12

The transition from a petroleum-based infrastructure to an industry which utilises renewable resources is one of the key research challenges of the coming years. Biomass, consisting of inedible plant material that does not compete with our food production, is a suitable renewable feedstock. In recent years, much research has been focused on developing new chemical strategies for the valorisation of different biomass components. In addition to the many heterogeneous and enzymatic approaches, homogenous catalysis has emerged as an important tool for the highly selective transformation of biomass, or biomass derived platform chemicals. This Perspective provides an overview of the most important recent developments in homogeneous catalysis towards the production and transformation of biomass and biomass related model compounds. The chemical valorisation of the main components of lignocellulosic biomass-lignin and (hemi)cellulose is reviewed. In addition, important new catalyst systems for the conversion of triglycerides and fatty acids are presented. © the Partner Organisations 2014.

International audience; This work reports on the synthesis of titanium bone implants functionalized with nanoparticles (NPs) containing Arg-Gly-Asp-Cys peptide (RGDC) and shows the adhesion behavior of cells seeded on these materials. RGDC peptides were first: conjugated to a norbornenyl-poly(ethylene oxide) macromonomer (Nb-PEO). Then, functional NPs with a size of similar to 300 nm and constituted of polynorbornene core surrounded by poly(ethylene oxide) shell were prepared by ring-opening metathesis polymerization in dispersed medium. The grafting density of these NPs on the titanium surface is up to 2 NPs.mu m(-2) (80 pmol of RGDC per cm(-2) of NP surface). Cell adhesion was evaluated using preosteoblast cells (MC3T3-E1). Results of cells cultured for 24 h showed that materials grafted with NPs functionalized with RGDC peptides enhance specific cell adhesion and can create filopodia-like among NP sites by stressing the cells.

Arene ruthenium(II) complexes containing bis(pyrazolyl)methane ligands have been prepared by reacting the ligands L' (L' in general; specifically L(1) = H(2)C(pz)(2), L(2) = H(2)C(pz(Me2))(2), L(3) = H(2)C(pz(4Me))(2), L(4) = Me(2)C(pz)(2) and L(5) = Et(2)C(pz)(2) where pz = pyrazole) with [(arene)RuCl(mu-Cl)](2) dimers (arene = p-cymene or benzene). When the reaction was carried out in methanol solution, complexes of the type [(arene)Ru(L')Cl]Cl were obtained. When L(1), L(2), L(3), and L(5) ligands reacted with excess [(arene)RuCl(mu-Cl)](2), [(arene)Ru(L')Cl][(arene)RuCl(3)] species have been obtained, whereas by using the L(4) ligand under the same reaction conditions the unexpected [(p-cymene)Ru(pzH)(2)Cl]Cl complex was recovered. The reaction of 1 equiv of [(p-cymene)Ru(L')Cl]Cl and of [(p-cymene)Ru(pzH)(2)Cl]Cl with 1 equiv of AgX (X = O(3)SCF(3) or BF(4)) in methanol afforded the complexes [(p-cymene)Ru(L')Cl](O(3)SCF(3)) (L' = L(1) or L(2)) and [(p-cymene)Ru(pzH)(2)Cl]BF(4), respectively. [(p-cymene)Ru(L(1))(H(2)O)][PF(6)](2) formed when [(p-cymene)Ru(L(1))Cl]Cl reacts with an excess of AgPF(6). The solid-state structures of the three complexes, [(p-cymene)Ru{H(2)C(pz)(2)}Cl]Cl, [(p-cymene)Ru{H(2)Cpz(4Me))(2)}Cl]Cl, and [(p-cymene)Ru{H(2)C(pz)(2)}Cl](O(3)SCF(3)), were determined by X-ray crystallographic studies. The interionic structure of [(p-cymene)Ru(L(1))Cl](O(3)SCF(3)) and [(p-cymene)Ru(L')Cl][(p-cymene)RuCl(3)] (L' = L(1) or L(2)) was investigated through an integrated experimental approach based on NOE and pulsed field gradient spin-echo (PGSE) NMR experiments in CD(2)Cl(2) as a function of the concentration. PGSE NMR measurements indicate the predominance of ion pairs in solution. NOE measurements suggest that (O(3)SCF(3))(-) approaches the cation orienting itself toward the CH(2) moiety of the L(1) (H(2)C(pz)(2)) ligand as found in the solid state. Selected Ru species have been preliminarily investigated as catalysts toward styrene oxidation by dihydrogen peroxide, [(p-cymene)Ru(L(1))(H(2)O)][PF(6)](2) being the most active species.

International audience; Polymacromonomers (PMs) are a class of branched polymers whose global shape depends strongly on the degree of polymerization of the backbone and the length of the side chain. As opposed to their equivalent linear chains, PMs can indeed adopt spherical, cylindrical, or wormlike shapes. Other parameters such as the rigidity of the side chain, the distance between branches and the interactions (incompatibility) between the backbone and the branches can also contribute to the global morphology of the PMs. In this work we describe the dynamical behavior of several poly(omega-norbornenyl polystyrene) differing by their backbone and their side chain lengths, in dilute and nondilute ranges of concentration, using dynamic light scattering and viscosity experiments. The results obtained, using both techniques, suggest dense and nonentangled particles as revealed by the low viscosity values and the scaling laws observed for the variation of the diffusion coefficient as a function of the molar mass and the concentration c. The transition from dilute to nondilute regime is characterized by an abrupt increase of the diffusion coefficient with the concentration, as opposed to the case of linear and flexible polymer coils. Above this concentration, the diffusion coefficient is independent of the molar mass and hardly varies with the concentration. It is identified as reflecting the overall collective motion of the branches. This transition is also observed in the variation of the reduced viscosity eta(sp)/c as a function of c. Similar studies have been carried out on star polymers of roughly same molar mass where no such an abrupt transition was observed.

The ring-opening polymerization of bicyclo[2.2.1]-hept-2-ene (norbornene, NBE) is carried out with the metathesis catalysts WCl6/RLi, where R = Me-, n-Bu-, sec-Bu-, tert-Bu-, sec-Bu-x-C-60(x-), sec-Bu-CH2-C(Ph)(2)(-), PS-. The bulkiness of the R chain of the co-catalyst, combined with the coordination of side substituents of R chain on the metal, increases the degree of cis-stereoselectivity of poly(NBE), beyond those of the systems based on WCl6 which are of intermediate cis-content. The range of the fraction of cis-double bonds varies from sigma(c) = 0.47 to an all-cis-polymer (sigma(c) = 0.96), and all the polymers derived exhibited a blocky distribution (r(c)r(t) > 1) of the double-bond dyads. In case of R = PS- an all-cis-poly(NBE) was formed. The observed order for the cis-stereoselectivity is: PS- > sec-Bu-CH2-C(Ph)(2)(-) > sec-Bu- > tert-Bu- > n-Bu- > sec-Bu-x-C-60(x-) > Me- (C) 2002 Elsevier Science B.V. All rights reserved. Journal of Molecular Catalysis a-Chemical