Search results for "Ring-opening metathesis polymerisation"
showing 10 items of 11 documents
Synthesis and biological evaluation of new bicyclic fluorinated uracils through ring-closing metathesis.
2006
Two families of bicyclic fluorinated uracils have been prepared starting from a gem-difluorinated unsaturated nitrile, by means of a ring-closing metathesis reaction to form the new ring, which is fused at the C-5/C-6 or N-1/C-6 positions of the uracil moiety. The selective formation of olefin regioisomers in the metathesis process can be controlled according to the reaction conditions (catalyst, solvent, and temperature). The acaricidal activities of the resulting compounds have also been investigated.
Olefin metathesis reactions with fluorinated substrates, catalysts, and solvents.
2014
New practical tungsten(VI) based catalyst systems for ring opening metathesis polymerisation
2002
Abstract Tungsten(VI) complexes of the type trans -[WCl 2 (diol)(OAr) 2 ] were studied as catalyst precursors for ROMP of norbornene and dicyclopentadiene. These compounds form active catalysts when treated by simple Grignard reagents, such as methyl magnesium iodide or neophyl magnesium chloride. Moreover, polymerisations can be run under ambient atmosphere without complicated inert atmosphere techniques.
End Capping Ring-Opening Olefin Metathesis Polymerization Polymers with Vinyl Lactones
2008
The selective placement of a functional group at the chain end of a ring-opening metathesis polymer using ruthenium carbene initiators has been a significant limitation. Here we demonstrate a highly effective and facile end-capping technique for ROMP with living ruthenium carbene chain ends using single-turnover olefin metathesis substrates. Vinylene carbonate and 3H-furanone are introduced as functionalization and termination agents for the ruthenium-initiated ring-opening metathesis polymerization. This leads directly to the formation of functional polymer end groups without further chemical transformation steps. Aldehyde and carboxylic acid end groups can be introduced by this new method…
1993
Poly(phosphonate)s via Olefin Metathesis: Adjusting Hydrophobicity and Morphology
2014
Olefin metathesis step-growth (acyclic diene metathesis (ADMET)) and chain-growth (ring-opening metathesis) polymerization was used to prepare linear poly(phosphonate)s with variable hydrophilicity. The first phosphonate monomer, i.e., di(undec-10-en-1-yl) methylphosphonate, for ADMET polymerization was developed, and potentially degradable and biocompatible, unsaturated poly(phosphonate)s were prepared with molecular weights up to 23 000 g mol–1 with molecular weight dispersities Đ < 2. These polymers were studied with respect to their interaction with a calcium phosphate bone substitute material from an aqueous nanoparticle dispersion that was prepared by a solvent evaporation miniemulsio…
Synthesis and characterization of amphiphilic comb-polymers via ring-opening metathesis polymerization of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[…
1994
A number of exo,exo-5,6-bis(alkoxymethyl)-7-oxabicyclo[2.2.1]hept-2-enes (exo,exo-5,6-bis(alkoxymethyl)-7-oxanorbornenes) with long alkyl chains were prepared by reduction of the Diels-Alder adduct of furan and maleic anhydride, followed by alkylation with a series of different n-alkylbromides. These monomers were polymerized via ring-opening metathesis polymerization (ROMP) catalyzed by ruthenium trichloride in ethanolic solution. Contrary to a helical conformation as it was predicted by a previous molecular model study the poly(7-oxanorbornenes) adopt a coil conformation in solution. In bulk the materials show side chain crystallization.
A “click” approach to ROMP block copolymers
2008
Amphiphilic block copolymers can be conveniently prepared via convergent syntheses, allowing each individual polymer block to be prepared via the polymerization technique that gives the best architectural control. The convergent “click-chemistry” route presented here, gives access to amphiphilic diblock copolymers prepared from a ring opening metathesis polymer and polyethylene glycol. Because of the high functional group tolerance of ruthenium carbene initiators, highly functional ring opening metathesis polymerization (ROMP) polymer blocks can be prepared. The described synthetic route allows the conjugation of these polymer blocks with other end-functional polymers to give well-defined a…
Functional end groups for polymers prepared using ring-opening metathesis polymerization.
2011
The precise placement of functional groups on the chain-ends of macromolecules is a major focus of polymer research. Most common living polymerization techniques offer specific methods of end-functionalization governed by the active propagating species and the kinetics of the polymerization reaction. Ring-opening metathesis polymerization has established itself as one of the most functional-group-tolerant living polymerization techniques known, but this tolerance has limited the number of available functionalization reactions. Metathesis chemists have therefore been required to develop a variety of end-functionalizations, adapting each of them to the reactivity scheme of the particular cata…