Polymer association and chain structure in anionic polymerization of dienes

1962 ◽  
Vol 2 (2) ◽  
pp. 106-107 ◽  
Author(s):  
Maurice Morton ◽  
N. Calderon ◽  
L. J. Fetters ◽  
J. F. Meier
Keyword(s):  
Anionic Polymerization ◽  
Chain Structure

Rapid Isolation of High Molecular Weight Urokinase from Native Human Urine

1982 ◽  
Vol 47 (03) ◽  
pp. 197-202 ◽  
Author(s):  
Kurt Huber ◽  
Johannes Kirchheimer ◽  
Bernd R Binder
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Human Urine ◽  
Gel Filtration ◽  
Chain Structure ◽  
The Other ◽  
Single Chain ◽  
Apparent Homogeneity ◽  
Sequential Adsorption

SummaryUrokinase (UK) could be purified to apparent homogeneity starting from crude urine by sequential adsorption and elution of the enzyme to gelatine-Sepharose and agmatine-Sepharose followed by gel filtration on Sephadex G-150. The purified product exhibited characteristics of the high molecular weight urokinase (HMW-UK) but did contain two distinct entities, one of which exhibited a two chain structure as reported for the HMW-UK while the other one exhibited an apparent single chain structure. The purification described is rapid and simple and results in an enzyme with probably no major alterations. Yields are high enough to obtain purified enzymes for characterization of UK from individual donors.

The anionic polymerization of cyanogen

1966 ◽  
Vol 31 (1) ◽  
pp. 243-251 ◽  
Author(s):  
J. Peška ◽  
M. J. Beneš ◽  
O. Wichterle
Keyword(s):  
Anionic Polymerization

Mechanism of the propagation step in the anionic polymerization of styrene

1980 ◽  
Vol 45 (4) ◽  
pp. 1047-1055 ◽  
Author(s):  
Miroslav Kašpar ◽  
Jiří Trekoval
Keyword(s):  
Experimental Data ◽  
Induction Period ◽  
Anionic Polymerization ◽  
Reactive Intermediate ◽  
Coordination Polymerization ◽  
Kinetic Dependence ◽  
Mathematical Solution ◽  
Slow Reaction

The paper is dealing with an investigation of the kinetic dependence of the propagation step in the anionic coordination polymerization of styrene in benzene at 303 K with "living" oligostyryllithium as initiator at the onset of the reaction. A short but distinct induction period was found, indicating a preceding slow reaction leading to the formation of a reactive intermediate, which behaves as the initiator of the reaction. Using results obtained in the first paper of this series, a new mechanism of propagation has been suggested, the mathematical solution of which is correlated with experimental data.

Kinetic Modelling of Anionic Polymerization Involving a Dynamic Equilibrium between Two Growth Centres with Different Growth Rates

1993 ◽  
Vol 58 (10) ◽  
pp. 2349-2361 ◽  
Author(s):  
Jaromír Jakeš
Keyword(s):  
Molecular Weight ◽  
Growth Rates ◽  
Anionic Polymerization ◽  
Dynamic Equilibrium ◽  
Kinetic Modelling ◽  
Polymerization Time ◽  
Fast State ◽  
Growth State ◽  
In The Beginning ◽  
Growth Centres

Kinetic modelling of the molecular weight distribution (MWD) of polymer obtained by an anionic polymerization with two types of growth centres in a dynamic equilibrium, having different growth rates and lifetimes comparable to the polymerization time, was made for low monomer conversions. On the basis of distribution of the growth centres according to the total time spent in the fast growth state, it was shown that MWD of the resulting polymer are mostly bimodal at the beginning of the polymerization and change to unimodal MWD at sufficiently high polymerization degrees depending on the equilibrization rate. When all centres are in the fast state in the beginning, MWD are essentially unimodal throughout. A hint of trimodality is observed in some cases, in an extent hardly detectable in real chromatograms. Hence, a polymodal MWD can be explained only when more than two growth centres with different growth rates are assumed.

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