Structural studies of oligosilanes produced by catalytic dehydrogenative coupling of primary organosilanes

1987 ◽  
Vol 65 (8) ◽  
pp. 1804-1809 ◽  
Author(s):  
C. Aitken ◽  
J. F. Harrod ◽  
U. S. Gill
Keyword(s):  
Molecular Weight ◽  
Nuclear Magnetic Resonance ◽  
Gel Permeation Chromatography ◽  
Structural Studies ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Dehydrogenative Coupling ◽  
Weight Distributions ◽  
Gel Permeation ◽  
End Groups

The structures of some poly(organosilylenes), [Formula: see text] (R = Ph, p-tolyl, n-hexyl, and benzyl), produced by catalytic dehydrogenative coupling of primary silanes have been studied by infrared, nuclear magnetic resonance, and mass spectroscopies. These results, combined with data on molecular weights and molecular weight distributions from vapour pressure osmometry and gel permeation chromatography, lead to the conclusion that the polymers are linear and have SiH2R end groups. The polymers all have degrees of polymerization of ca. 10 and very narrow molecular weight dipersions. Some possible features of the mechanism that gives rise to this behaviour are discussed.

Molecular Weight Distributions of Elastomers—Comparison of Gel Permeation Chromatography with Other Techniques

1965 ◽  
Vol 38 (4) ◽  
pp. 823-831 ◽  
Author(s):  
Leon W. Gamble ◽  
Lowell Westerman ◽  
Ebnest A. Knipp
Keyword(s):  
Molecular Weight ◽  
Molecular Weight Distribution ◽  
Weight Distribution ◽  
Gel Permeation Chromatography ◽  
Molecular Weights ◽  
The Past ◽  
Molecular Weight Distributions ◽  
Weight Distributions ◽  
Gel Permeation ◽  
Polymer Fractionation

Abstract During the past decade interest in polymer fractionation for evaluating molecular weight distribution has increased. New polymers, such as polypropylene, high density polyethylene and many others have been subjected to extensive characterization, but some older polymers, including natural rubber have not. In recent years column fractionation has received a great deal of attention; a review has been made by Schneider. Most of the techniques of polymer fractionation, such as precipitation from solution and column fractionation, are quite lengthy and require days or even weeks to complete. A more rapid method for molecular weight distribution has been the goal of polymer chemists for years. The most promising of the rapid methods are turbidimetric and gel permeation chromatography by which analysis is accomplished in a few hours. This paper discusses application of gel permeation chromatography to fractionation of elastomers. In addition this technique is compared with data from column fractionation, light scattering and osmometry. Some of the assumed factors used in converting gel permeation data into molecular weights are in error. But by calibration of the gel permeation chromatograph with classical methods reliable data can be obtained.

Fe-mediated ICAR ATRP of methyl methacrylate on photoinduced miniemulsion polymerization

e-Polymers ◽  
2016 ◽  
Vol 16 (1) ◽  
pp. 41-47 ◽  
Author(s):  
Xue-Hui Zhan
Keyword(s):  
Methyl Methacrylate ◽  
Miniemulsion Polymerization ◽  
Gel Permeation Chromatography ◽  
Polymerization Time ◽  
Molecular Weights ◽  
Molecular Weight Distributions ◽  
Chloride Hexahydrate ◽  
Weight Distributions ◽  
Gel Permeation ◽  
Ferric Chloride Hexahydrate

AbstractThe initiators for continuous activator regeneration (ICAR) atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) were investigated in microemulsion under light irradiation with ethyl 2-bromoisbutyrate (EBiB) as an ATRP initiator, ferric chloride hexahydrate (FeCl3·6H2O) as a catalyst, N,N,N′,N′-tetramethyl-1,2-ethanediamine (TMEDA) as a ligand, and azobisisobutyronitrile (AIBN) as an initiator and reducing agent. The linear dependence of ln([M]0/[M]) on polymerization time was observed, indicating that the polymerization was living polymerization. Furthermore, the number-average molecular weights (Mn), gel permeation chromatography (GPC) and molecular weight distributions (MWD) of the PMMA obtained from GPC were controlled. The product was characterized by 1H nuclear magnetic resonance (NMR) and GPC. The living features were verified by chain-extended with MMA with the obtained PMMA as macroinitiator.

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