نتایج جستجو برای: ring opening polymerization
تعداد نتایج: 195988 فیلتر نتایج به سال:
We report here the integration of ring-opening metathesis polymerization (ROMP) and ring-opening polymerization of the amino acid N-carboxyanhydride (NCA) to allow facile synthesis of brush-like polymers containing polypeptide as the brush side chains. ROMP of N-trimethylsilyl norbornenes rendered the preparation of poly(norbornene)s bearing pendant N-TMS groups. With no need to purify the resu...
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 ...
Poly(α-hydroxy acids), as a family of biodegradable polyesters, are valuable materials due to their broad applications in packaging, agriculture, and biomedical engineering. Herein we highlight explore recent advances catalysts controlled ring-opening polymerization O-carboxyanhydrides towards functionalized poly(α-hydroxy especially metal catalyst-mediated polymerization. Limitations current s...
The uranyl aryloxide, [UO2(OAr)2(THF)2], and uranyl chloride, [UO2Cl2(THF)3] or [UO2Cl2(THF)2]2 act as pre-catalysts for the ring opening polymerization of propylene oxide and cyclohexene oxide. Coordination of the monomers has been investigated using H EXSY spectroscopy and kinetic and thermodynamic parameters reported. NMR analyses of the polymers suggest a bimetallic mechanism for the polyme...
The activity of cerium alkoxide complexes supported by a Schiff base ligand was controlled using redox reagents during the ring-opening polymerization of L-lactide. The rate of L-lactide polymerization was modified by switching in situ between the cerium(III) and cerium(IV) species.
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...
A new and general strategy for the synthesis of sequence-defined polymers is described that employs relay metathesis to promote the ring opening polymerization of unstrained macrocyclic structures. Central to this approach is the development of a small molecule "polymerization trigger" which when coupled with a diverse range of sequence-defined units allows for the controlled, directional synth...
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