Emulsion polymerization of chloroprene. I. Mechanism

Morton, Maurice; Cala, J. A.; Altier, Mary W.

doi:10.1002/pol.1956.120199315

Cited by 24 publications

(2 citation statements)

References 18 publications

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“…Often the compositions are critically specifi~,'~ the proper proportions for polymerization of butadiene being unsuitable for isotactic polymerization of styreiie. 15 Stretching of an ionic bond causes, first, some separation of anion from cation, followed by formation of two radicals, 16 This is inevitable, because the ionization potential of the metal (117.0 kcal./ mole) greatly exceeds the electron affinity of carbon (about 31 kcal./ mole) 17. Moreover, some simple reactions suggest that the biradical state is, indeed, achieved; the alkylatioii'8 of cumeiie or cymene by ethylene, sodium, and a promoter, and the cleavage of etherslg are examples.…”

Section: (1)mentioning

confidence: 99%

Stepwise and catalytic polymerization of butadiene by organosodium reagents

Morton

Lanpher

1960

J. Polym. Sci.

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For many years the polymerizations of butadiene by organosodium reagents in this laboratory have fallen into two extreme categories: one, long known and well defined in the literature,' is a relatively slow, stepwise growth, primarily in a 1,2-manner; the other is a rapid catalytic process which cannot be interrupted. The latter is best illustrated by the combination2 of allylsodium, sodium isopropoxide, and sodium chloride which induces primarily 1,4-polymerization, mostly to a trans form; possibly because a simultaneous change about the double bond occurs, organosodium compounds being active agents for isomerization, even at room temperature.3These two types can be distinguished by comparing polymerizations with additions to 1,l-diphenylethylene, a prototype for that kind of reaction; data for that purpose are a t hand from previous publications. Figure 1 shows a plot of the relative yields obtained in additions4+ against the yields obtained in polymerizations, each to the basis of amylsodium as 1.The stepwise processes lie on the upper line; the catalytic one^?^^^^ are on a lower line and best a t the lower right. Amylpotassiumx lies between the two lines but, all things considered, (i.e., yield, viscosity, an infrared absorption) might be regarded as in the catalytic area. The cation, being different from those in the reactions to which this is compared, probably affects that case, because potassium and sodium reagents do not always behave alike, even in a simple m e t a l a t i~n .~~~ The viscosities for the polybutadienes on the upper line are low and of the same order of magnitude (0.1 to 0.2). That result could be expected, as, after one or two dienes have added, the growing ends should be identical, and thereafter the chain lengths should become similar.The catalytic processes are distinguished for their failure to follow that rule. In some way the diene molecules are concentrated a t the growing end, so that they join the chain with unusual rapidity. A high concentration must come, logically, from a preferred or orderly adsorption, as contrasted with random adsorption for stepwise polymerization. 233Both axes are graded logarithmically.

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Section: (1)mentioning

confidence: 99%

Stepwise and catalytic polymerization of butadiene by organosodium reagents

Morton

Lanpher

1960

J. Polym. Sci.

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“…The network is necessarily restricted to the particle volume, and it has no consequence on the latex rheology. Although polychloroprene has been produced commercially since the beginning of the 1930s, few authors have published on the polymerization mechanisms of this monomer as well as on its gel formation. − Like any difunctional monomer, chloroprene leads to branching and cross-linking as the reaction proceeds to high conversion. On a theoretical point of view, it is admitted that gel formation in chloroprene polymerization may result from either additions to the residual double bonds of polychloroprene chains or transfer to polymer, followed by termination .…”

Section: Introductionmentioning

confidence: 99%

Emulsion Polymerization of Chloroprene in the Presence of a Maleic Polymerizable Surfactant: Control of Gel Formation at Low Conversion

et al. 2004

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Chloroprene was polymerized in emulsion, using a redox system as initiator. With a rosin derivative as surfactant, gel formation was avoided until ca. 70% conversion, but when a reactive maleic hemiester surfactant was used, gel could appear at conversions as low as 5%. The purpose of this paper is to show how this problem of early gel formation can be controlled via the flux of radicals entering the particles. Using more initiator leads to shorter polymer chains, a delayed onset of gel formation, and paradoxically to slower polymerizations.

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Ermittlung der mittleren Radikalkonzentration pro Latexteilchen bei der Emulsionspolymerisation

Gerrens

1959

Angewandte Chemie

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Methode erhaltenen Produkte zeigen diese Nachteile der Suspensionsprodukte nicht. Emulgatorreste verschlechtern jedoch gewisse lacktechnischen Eigenschaften wie Wasserund Chemikalienbestandigkeit, Haftvermogen auf Metalloberflachen u.a.m.Aus den Tabellen 11 und 12 laBt sich entnehmen, da6 Vinylchlorid-Vinylacetat-Mischpolymerisate rnit verbesserten Eigenschaften mit Hilfe spaltbarer Emulgatoren hergestellt werden konnen.

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Emulsion polymerization of chloroprene. I. Mechanism

Cited by 24 publications

References 18 publications

Stepwise and catalytic polymerization of butadiene by organosodium reagents

Stepwise and catalytic polymerization of butadiene by organosodium reagents

Emulsion Polymerization of Chloroprene in the Presence of a Maleic Polymerizable Surfactant: Control of Gel Formation at Low Conversion

Ermittlung der mittleren Radikalkonzentration pro Latexteilchen bei der Emulsionspolymerisation

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