نتایج جستجو برای: Ring-opening metathesis polymerization

تعداد نتایج: 197458  

Journal: :Journal of the American Chemical Society 2015
Ho-Keun Lee Ki-Taek Bang Andreas Hess Robert H Grubbs Tae-Lim Choi

We demonstrated tandem ring-opening/ring-closing metathesis (RO/RCM) polymerization of monomers containing two cyclopentene moieties and postmodification via insertion polymerization. In this system, well-defined polymers were efficiently formed by tandem cascade RO/RCM reaction pathway. Furthermore, these polymers could be transformed to new A,B-alternating copolymers via a sequential cross me...

2003

Olefin metathesis polymerization, in particularly ring-opening metathesis polymerization (ROMP), has been a popular topic of modern research. Two other types are acyclic diene metathesis polymerization (ADMET) and cyclopolymerization of diynes. To date, there has been no report on a metathesis polymerization utilizing more than one metathesis process. Herein, the concept of multiple olefin meta...

Journal: :Organometallics 2010
Benjamin K Keitz Robert H Grubbs

Ru-based olefin metathesis catalysts containing carbohydrate-derived NHCs from glucose and galactose were synthesized and characterized by NMR spectroscopy. 2D-NMR spectroscopy revealed the presence of Ru-C (benzylidene) rotamers at RT and the rate of rotation was measured using magnetization transfer and VT-NMR spectroscopy. The catalysts were found to be effective at ring-opening metathesis p...

Journal: :Journal of Polymer Science Part A: Polymer Chemistry 2019

Journal: :Chemical communications 2011
Yugang Bai Hua Lu Ettigounder Ponnusamy Jianjun Cheng

Linear hybrid block copolymers with well controlled molecular weights and narrow polydispersities were synthesized via ring-opening metathesis polymerization (ROMP) followed by ring-opening polymerization of amino acid N-carboxyanhydrides.

Journal: :Polyhedron 2014
Melanie A Pribisko Tonia S Ahmed Robert H Grubbs

Two new Ru-based metathesis catalysts, 3 and 4, have been synthesized for the purpose of comparing their catalytic properties to those of their cis-selective nitrate analogues, 1 and 2. Although catalysts 3 and 4 exhibited slower initiation rates than 1 and 2, they maintained high cis-selectivity in homodimerization and ring-opening metathesis polymerization reactions. Furthermore, the nitrite ...

Journal: :Journal of the American Chemical Society 2015

Journal: :Advanced synthesis & catalysis 2016
David Martin Vanessa M Marx Robert H Grubbs Guy Bertrand

A ruthenium complex bearing an "anti-Bredt" N-heterocyclic carbene was synthesized, characterized and evaluated as a catalyst for olefin metathesis. Good conversions were observed at room temperature for the formation of di- and tri-substituted olefins by ring-closing metathesis. It also allowed for the ring-opening metathesis polymerization of cyclooctadiene, as well as for the cross-metathesi...

Journal: :Journal of the American Chemical Society 2012
Benjamin K Keitz Alexey Fedorov Robert H Grubbs

Cis-selective ring-opening metathesis polymerization of several monocyclic alkenes as well as norbornene and oxanorbornene-type monomers using a C-H activated, ruthenium-based metathesis catalyst is reported. The cis content of the isolated polymers depended heavily on the monomer structure and temperature. A cis content as high as 96% could be obtained by lowering the temperature of the polyme...

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