Observation and analysis of a slow termination process in the atom transfer radical polymerization of styrene
摘要:
Under conditions in which the rate of polymerization is slow, we have observed the slow elimination of HBr from the polymer endgroups in the ATRP of styrene. Experimental evidence indicates that this process is likely due to the solvent effect on the stability of 1-PEBr at 110 degrees C. A second elimination reaction was observed in a hydrocarbon solvent. The major contribution to the second elimination process comes from the reaction of the Cu(II) species, formed after atom transfer, with the growing polymeric radical which presumably occurs via a one electron oxidation process. The bimolecular rate constant for the reaction of the growing polymeric radical with the Cu(II) species in an atom transfer process is approximately 10(3) to 10(4) times greater than for the same in a termination process. Thus, the chemoselectivity for atom transfer is very high, and the effect of this termination reaction is minimal under conditions in which the concentration of monomer is high and the concentration of Cu(II) species is at the minimum necessary to ensure good molecular weight control. These data also suggest that effect of this reaction is negligible for styrene polymerizations yielding low molecular weight polymer and that it should result in an upper molecular weight limit to styrene ATRP. (C) 1997 Elsevier Science Ltd.
[EN] AMINO-REACTIVE POSITIVELY CHARGED ATRP INITIATORS THAT MAINTAIN THEIR POSITIVE CHARGE DURING SYNTHESIS OF BIOMACRO-INITIATORS<br/>[FR] INITIATEURS ATRP À CHARGE POSITIVE AMINO-RÉACTIFS MAINTENANT LEUR CHARGE POSITIVE PENDANT LA SYNTHÈSE DE BIOMACRO-INITIATEURS
申请人:RUSSELL ALAN J
公开号:WO2020028715A1
公开(公告)日:2020-02-06
Provided herein are materials and methods that include utilizing atom transfer radical polymerization (ATRP) initiator molecules that maintain a positive charge during biomacro-initiator synthesis.
Provided is a catalyst used for a living radical polymerization method, which contains a central element consisting of carbon and at least one halogen atom binding to the central element. Further, a hydrocarbon compound can be used as a catalyst precursor. A monomer having a radical-reactive unsaturated bond is subjected to a radical polymerization reaction in the presence of the catalyst, consequently a polymer having narrow molecular weight distribution can be obtained, and thus the cost of the living radical polymerization can be remarkably reduced. The present invention is significantly more environmentally friendly and economically excellent than conventional living radical polymerization methods, due to advantages such as low toxicity of the catalyst, low amount of the catalyst used, high solubility of the catalyst, mild reaction conditions, and no coloration/no odor (no need of any post-treatments for a molded article), and the like.
Dental Materials Based On Redox Systems With Low-Odour Cumene Hydroperoxide Derivatives
申请人:Ivoclar Vivadent AG
公开号:US20200253837A1
公开(公告)日:2020-08-13
Radically polymerizable dental material, which contains a combination of a thiourea derivative and a hydroperoxide according to the following Formula (I) as initiator system for the radical polymerization:
具有以下公式(I)中的硫脲衍生物和过氧化氢的组合的根本聚合牙科材料,作为自由基聚合的引发体系。
Controlled/“Living” Radical Polymerization. Kinetics of the Homogeneous Atom Transfer Radical Polymerization of Styrene
作者:Krzysztof Matyjaszewski、Timothy E. Patten、Jianhui Xia
DOI:10.1021/ja963361g
日期:1997.1.1
ligand-to-copper(I) halide for these polymerizations was found to be 2:1, which tentatively indicates that the coordination sphere of the active copper(I) center contains two bipyridine ligands. The exclusive role for this copper(I) complex in ATRP is atom transfer, since at typical concentrations that occur for these polymerizations (≈10-7−10-8 M), polymeric radicals were found not to react with the copper(I) center
The invention relates to novel dendritic molecules and methods of making them. The dendritic molecules comprise arms, each of which arms is a polymer. The dendritic molecules can be synthesised by way of a reasonably small number of versatile and reliable step-wise reactions, especially click chemistry reactions. Chemical and structural heterogeneity is possible in the dendritic molecule. The invention also provides for surface and interior functionalisation of the molecule.