Search results for "Nitroxide mediated radical polymerization"
showing 10 items of 35 documents
Star-Like Polymers of tert -Butyl Acrylate via Controlled Radical Polymerization - Synthesis and Properties
2011
Summary: Star polymers with different numbers and lengths of poly(tert-butyl acrylate) arms were obtained by the core-first method via atom transfer and iodine mediated radical polymerization. Multifunctional initiators with different numbers of initiating groups (from 3 to 28) were used to initiate the polymerization of tert-butyl acrylate, yielding stars with different numbers of arms. The structures of the stars were characterized by NMR and gel permeation chromatography with refractive index, multiangle laser light scattering and viscosimetric detectors.
Controlled radical polymerization of alkyl acrylates and styrene using a half-sandwich molybdenum(III) complex containing diazadiene ligands
2003
Abstract The half-sandwich molybdenum(III) complex CpMoCl 2 ( i Pr 2 -dad) ( i Pr 2 -dad= i Pr–NCH–CHN– i Pr) proved to be an effective metal catalyst for the controlled radical polymerization of methyl acrylate, butyl acrylate, and styrene. In conjunction with an alkyl iodide [R–I: CH 3 CH(COOEt)I] as an initiator and in the presence or absence of Al(O– i -Pr) 3 as a co-catalyst, the molybdenum-based system gave polymers with narrow molecular weight distributions. The in situ addition of styrene to a macroinitiator of poly(methylacrylate) afforded an AB-type block copolymer.
Tailored Semiconducting Polymers: Living Radical Polymerization and NLO-Functionalization of Triphenylamines
2002
This paper describes the preparation of various polymers with triarylamine side groups. High molecular weight materials were obtained by free radical polymerization utilizing the gel effect. Polymers with a marrow polydispersity and a predetermined molecular weight could be prepared by living radical polymerization. The T g could, thereby, be controlled between 50 and 140°C either by using different monomers or by varying the molecular weight. Living radical polymerization allowed in addition the preparation of block copolymers. The triarylamine side groups could be transformed into NLO-chromophores by reaction with tetracyanoethylene. This leads to the incorporation of tricyanoethylene. Th…
Cyclodextrins in Polymer Synthesis: Free-Radical Polymerization of Methylated β-Cyclodextrin Complexes of Methyl Methacrylate and Styrene Controlled…
2000
Polymerization of an activated ester monomer based on 4-vinylsulfonic acid and its polymer analogous reaction
2011
Homopolymers containing sulfonic ester side groups were synthesized by reversible addition–fragmentation chain transfer (RAFT) polymerization utilizing benzyl dithiobenzoate, cumyl dithiobenzoate, and 4-cyano-4-((thiobenzoyl)sulfanyl)pentanoic acid as chain transfer agents. Likewise diblock copolymers containing poly(styrene), poly(octylstyrene) and poly(pentafluorostyrene) as the second block were synthesized. Additionally, nitroxide mediated polymerization (NMP) was investigated for the synthesis of a homopolymer as well as for a diblock copolymer. Furthermore, the post-polymerization functionalization with various amines to yield the respective sulfonamides was conducted. The conversion …
Half-sandwich molybdenum(III) compounds containing diazadiene ligands and their use in the controlled radical polymerization of styrene
2002
Abstract The reaction of CpMoCl2 with diazadiene ligands RNCHCHNR (R2dad) affords the corresponding paramagnetic complexes CpMoCl2(R2dad) (R=Ph, 1; p-Tol, 2; C6H3Pr2i-2,6, 3; and Pri, 4). All compounds have been characterized by EPR spectroscopy and have been investigated by cyclic voltammetry. They display one-electron oxidation and reduction processes, these being reversible or irreversible depending on the nature of R. The irreversibility of the reduction wave is due to a chemical follow-up process which consists of chloride loss from the reduced product. This phenomenon is suppressed in the presence of excess chloride in solution. An X-ray structure of 3 verifies the mononuclear na…
How the interplay of different control mechanisms affects the initiator efficiency factor in controlled radical polymerization: An investigation usin…
2007
International audience; Compound CpMoI2(iPr2dad) (iPr2dad = iPrNdouble bondCHsingle bondCHdouble bondNiPr), obtained by halide exchange from CpMoCl2(iPr2dad) and NaI, has been isolated and characterized by EPR spectroscopy, cyclic voltammetry, and X-ray crystallography. Its action as a catalyst in atom transfer radical polymerization (ATRP) and as a spin trap in organometallic radical polymerization (OMRP) of styrene and methyl acrylate (MA) monomers has been investigated and compared with that of the dichloro analogue. Compound CpMoCl2(iPr2dad) catalyzes the ATRP of styrene and MA with low efficiency factors f (as low as 0.37 for MA and ethyl 2-chloropropionate as initiator), while it irre…
Half-sandwich Mo(III) complexes with asymmetric diazadiene ligands
2006
The asymmetric 1,4-diazadiene ligands R ∗ N CHCH NR ∗ [R ∗ = ( S )-CH(CH 3 )Ph], R 2 ∗ dad , and 2,2′-bis(4-ethyloxazoline), as-ox, have been used to generate half-sandwich Mo III derivatives by addition to Cp 2 Mo 2 Cl 4 . Ligand R 2 ∗ dad affords a mononuclear, paramagnetic 17-electron product, CpMoCl 2 ( R 2 ∗ dad ) , whereas as-ox leads to the isolation of a dinuclear compound where only one molecule of ligand has been added per two Mo atoms, Cp 2 Mo 2 Cl 4 (as-ox). In the presence of free as-ox, this compound coexists with the paramagnetic mononuclear complex in solution. Both products are capable of controlling the radical polymerization of styrene under typical atom transfer radical…
Hybrid Magnetic Materials Based on Nitroxide Free Radicals and Extended Oxalato‐Bridged Bimetallic Networks
2005
A series of hybrid organic-inorganic magnets of formula p-rad[MIICr(ox)3] [M = Mn (1), Co (2), Ni (3), Zn (4)] and m-rad[MIICr(ox)3] [M = Mn (5), Co (6)], in which N-methylpyridinium cations bearing a nitronyl nitroxide moiety in positions 3 (m-rad) or 4 (p-rad) of the pyridine ring coexist with the 2D honeycomb-like oxalato-bridged bimetallic lattice, has been prepared and studied by AC and DC magnetic susceptibility measurements and EPR spectroscopy. In general, the physical properties of these magnets are not altered significantly by the insertion of the nitronyl nitroxide radicals although these paramagnetic molecules seem to interact weakly with the inorganic network as demonstrated by…
Heparin–polynitroxides: Synthesis and preliminary evaluation as cardiovascular EPR/MR imaging probes and extracellular space-targeted antioxidants
2011
We report here the synthesis of heparin-polynitroxide derivatives (HPNs) in which nitroxide moieties are linked either to uronic acid or glycosamine residues of the heparin macromolecule. HPNs have low anticoagulant activity, possess superoxide scavenging properties, bind to the vascular endothelium/extra-cellular matrix and can be detected by EPR and MRI techniques. As the vascular wall-targeted redox-active paramagnetic compounds, HPNs may have both diagnostic (molecular MRI) and therapeutic (ecSOD mimics) applications.