Supercritical fluid chromatography of styrene oligomers

Klesper, E.; Hartmann, W.

doi:10.1002/pol.1977.130150102

Cited by 41 publications

(11 citation statements)

References 7 publications

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“…Many choices of solvent and column types are available. Polystyrene was analyzed by this technique in 1969 by Jentoft and Gouw (64,65) and later by others (66,67). Using packed capillary columns the resolution of oligomers containing 70 repeat units has been achieved (68).…”

Section: Characterization Of Oligomeric Materialsmentioning

confidence: 99%

Recent advances in molecular weight determination

Cooper

1989

Polymer Engineering & Sci

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The aging and lifetimes of polymeric materials depend on the reaction of these materials to the particular stresses which are applied. In many cases the molecular weight of the polymer is changed and this affords a way to follow aging phenomena. In the simplest case a homopolymer is subjected to a stress which increases or decreases its molecular weight without any chemical changes. As the situation becomes more complicated, changes in chemical composition occur and different sized molecular species are generated. These new species may be of extremely low molecular weight or they may be in the form of crosslinked gel. This paper reviews methods which are available for the determination of molecular weight and molecular weight distribution of polymeric materials. Recently developed or modified techniques are treated in more detail. Techniques which may be used to characterize the oligomer region or analyze for the presence of crosslinked gel are included.

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Section: Characterization Of Oligomeric Materialsmentioning

confidence: 99%

Recent advances in molecular weight determination

Cooper

1989

Polymer Engineering & Sci

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“…Klesper has pioneered the use of IH_ and 13C_ magnetic resonance to monitor chemical reactions of polymers and has done extensive work on the hydrolysis of isotactic and syndiotactic polyMMA [50][51][52][53][54], on the reactions of diazoalkanes with isotactic and syndiotactic poly(methacrylic acid) [55,56], and on the esterification of poly(methacrylic acids) with alcohols in the presence of carbodiimides [57,58], As an example of the results obtained in these studies, Figure 1 shows the 220 MHz PMR spectra of several syndiotactic methacrylic acid(A)-methyl methacrylate(M) copolymers prepared by the hydrolysis of syndiotactic poly(methyl methacrylate). Separate resonances are evident for the a-methyl protons centered in AAA, (MAA+AAM) , MAM, AMA, (AMM+MMA) and MMM triads.…”

Section: Utilization Of N-add Distributions Measured By Nmrmentioning

confidence: 99%

NMR Analysis of Stereo Regular Copolymers

Harwood

1979

Preparation and Properties of Stereoregular Polymers

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Stereoregular copolymers are formed by the chemical modification of stereoregular polymers, by copolymerizations of ~-olefins in the presence of stereoregulating catalysts and by ring opening copolymerizations of chiral monomers. Also appropriate for consideration are polydienes containing cis-l,4-and trans-l,4-units as well as those containing 1,2-{or 3,4-) and 1,4-units. Analysis of such copolymers by NMR spectroscopy provides information about their compositions and the arrangement of monomer units along their chains. Such information is valuable for understanding the chemical behavior of stereoregular polymers and the mechanisms of stereoregular polymerization processes. STRUCTURAL FEATURES PRESENT IN STEREOREGULAR COPOLYMERSIf a stereoregular copolymer containing A and B monomer units is considered, then some of its structural features that can be measured by NMR spectroscopy can be listed as follows.

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“…The microbore columns play both the role of sampling and a loop of the sample injector (8). The time required for extract loading is 10 to 60 s. The sample mass deposited on the columns is controlled by the loading period.…”

Section: Directmentioning

confidence: 99%

“…The sample loop (1 µl) is of negligible volume compared to the volume of the extraction vessel (3), 2 ml, plus the associated volumes of the line and hydraulic components. The SFC section comprises PUMP 3, a microbore separation column (4) of 0.8 mm i.d.X50 mm length, a detection system (5,6), a back-pressure regulator (7) and a mass flowmeter (8). The SFC section is connected with the SFE section via VALVE 1.…”

Section: Directmentioning

confidence: 99%

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Coupling of Supercritical Fluid Extraction with Chromatography

Jinno

Saito²

1991

ANAL. SCI.

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Coupling methods between supercritical fluid extraction (SFE) and various chromatographic techniques have been reviewed. Developments using supercritical fluids in chromatography have been tremendous and a confirmation of the usefulness of this technique (called supercritical fluid chromatography (SFC)) has been evidenced by many scientists. Another field using supercritical fluids in analytical processes is SFE. Since SFE has many advantages compared to conventional solvent extraction method, such as faster and better controllability of conditions, no requirements for solvent waste and lower cost, popularity has been recently increasing. The most promising and favorable advantage of SFE is, however, the possibility to directly combine the extraction process to additional separation processes. The combination of SFE and various chromatographic techniques can be established more easily than the conventional solvent extraction technique. This review will mainly describe the potential of SFE, especially focusing on the coupling of SFE with chromatographic techniques. The review on SFC is also included since SFC is the major technique in which supercritical fluids are effectively used and no discussion concerning SFE is possible without knowledge about SFC.

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Supercritical fluid chromatography of styrene oligomers

Cited by 41 publications

References 7 publications

Recent advances in molecular weight determination

Recent advances in molecular weight determination

NMR Analysis of Stereo Regular Copolymers

Coupling of Supercritical Fluid Extraction with Chromatography

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