Ethene−Norbornene Copolymerization with Homogeneous Metallocene and Half-Sandwich Catalysts:  Kinetics and Relationships between Catalyst Structure and Polymer Structure. 3. Copolymerization Parameters and Copolymerization Diagrams

1998 ◽  
Vol 31 (15) ◽  
pp. 4681-4683 ◽  
Author(s):  
Dieter Ruchatz ◽  
Gerhard Fink
Keyword(s):  
Polymer Structure ◽  
Catalyst Structure ◽  
Half Sandwich

Elastomeric Poly(propylene): Influence of Catalyst Structure and Polymerization Conditions on Polymer Structure and Properties

1995 ◽  
Vol 28 (11) ◽  
pp. 3771-3778 ◽  
Author(s):  
William J. Gauthier ◽  
John F. Corrigan ◽  
Nicholas J. Taylor ◽  
Scott Collins
Keyword(s):  
Polymer Structure ◽  
Structure And Properties ◽  
Catalyst Structure ◽  
Poly Propylene ◽  
Polymerization Conditions

ULTRASONIC STUDIES OF THE POLYMER STRUCTURE OF THE CHALCOGENIDE GLASSES

1981 ◽  
Vol 42 (C4) ◽  
pp. C4-955-C4-958
Author(s):  
V. A. Ratobylskaja ◽  
L. A. Simonova
Keyword(s):  
Chalcogenide Glasses ◽  
Polymer Structure

Half- Sandwich cyclopentadienylruthenium(II) Complexes: A New Antimalarial Chemotype

2020 ◽  
Author(s):  
Sofia Alexandra Milheiro ◽  
Joana Gonçalves ◽  
Ricardo Lopes ◽  
Margarida Madureira ◽  
Lis Lobo ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Blood Stage ◽  
Nuclear Accumulation ◽  
Selective Absorption ◽  
Asexual Parasite ◽  
Single Digit ◽  
Liver Stage ◽  
Dual Stage ◽  
Fluorescent Compounds ◽  
Half Sandwich

<p><a>A small library of “half-sandwich” cyclopentadienylruthenium(II) compounds of general formula [(</a>η<sup>5</sup>-C<sub>5</sub>R<sub>5</sub>)Ru(PPh<sub>3</sub>)(N-N)][PF<sub>6</sub>], a scaffold hitherto unfeatured in the toolbox of antiplasmodials, was screened for activity against the blood stage of CQ-sensitive 3D7-GFP, CQ-resistant Dd2 and artemisinin-resistant IPC5202 <i>Plasmodium falciparum</i> strains, and the liver stage of <i>P. berghei</i>. The best performing compounds displayed dual-stage activity, with single-digit nM IC<sub>50</sub> values against blood stage malaria parasites, nM activity against liver stage parasites, and residual cytotoxicity against mammalian cells (HepG2, Huh7). Parasitic absorption/distribution of 7-nitrobenzoxadiazole-appended fluorescent compounds <b>Ru4</b> and <b>Ru5</b> was investigated by confocal fluorescence microscopy, revealing parasite-selective absorption in infected erythrocytes and nuclear accumulation of both compounds. The lead compound <b>Ru2</b> impaired asexual parasite differentiation, exhibiting fast parasiticidal activity against both ring and trophozoite stages of a synchronized <i>P. falciparum</i> 3D7 strain. These results point to cyclopentadienylruthenium(II) complexes as a highly promising chemotype for the development of dual-stage antiplasmodials.</p>

Biodegradable Polyurethanes Cross-Linked by Multifunctional Compounds

2017 ◽  
Vol 14 (6) ◽  
pp. 778-784 ◽  
Author(s):  
Joanna Brzeska
Keyword(s):  
Polymer Structure ◽  
Cross Linking ◽  
Plant Oils ◽  
Lignocellulosic Materials ◽  
Soft Or ◽  
Native State ◽  
Synthetic Compounds ◽  
Multifunctional Compounds ◽  
Hard Segments ◽  
Synthetic Origin

Background: Cross-linking structure of polyurethanes determines no degradability of these materials. However, introducing the hydrolysable substrates (of natural or synthetic origin) into the cross-linked polyurethanes structure makes them biodegradable. Moreover compounds (such as polycaprolactone triol, glycerin, lysine triisocyanate, etc.) that are used for polyurethane cross-linking are degraded in non-toxic products. All these kinds of compounds can be introduced into soft or hard segments via urethane bonds. Objective: The review focuses on kind of multifunctional polyols and isocyanates, and low molecular crosslinkers used for cross-linked polyurethanes obtaining. These compounds are natural substrates (in the native state or after modification) or are synthetic compounds with degradable linkages. They belong to polyesters, plant oils, proteins, saccharides, and others (e.g. lignocellulosic materials), and they are synthesized chemically or via biosynthesis by algae, plants, microorganisms, and by animals. Conclusion: Incorporation of degradable groups (such as ester moieties) into the polymer structure, and using of substrates with the structure known and metabolized by microorganisms for soft or hard segments building, facilitate degradation of cross-linked polyurethanes.

Polymer structure and catalytic activity of ion exchangers

1981 ◽  
Vol 46 (7) ◽  
pp. 1577-1587 ◽  
Author(s):  
Karel Jeřábek
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Active Sites ◽  
Crosslinking Agent ◽  
Reaction Medium ◽  
Polymer Structure ◽  
Local Concentration ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene ◽  
Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

Thermally Stable Half-Sandwich Benzhydryl Ln(II) (Ln = Sm, Yb) Complexes Supported by Sterically Demanding Carbazolyl and Fluorenyl Ligands

2019 ◽  
Vol 38 (24) ◽  
pp. 4615-4624 ◽  
Author(s):  
Alexander N. Selikhov ◽  
Andrey S. Shavyrin ◽  
Anton V. Cherkasov ◽  
Georgy K. Fukin ◽  
Alexander A. Trifonov
Keyword(s):  
Thermally Stable ◽  
Sterically Demanding ◽  
Half Sandwich
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