Composition and molecular weight distribution of block copolymers

Tanaka, Takeshi; Omoto, Mitsuru; Donkai, Nobuo; Inagaki, Hiroshi

doi:10.1080/00222348008213121

Cited by 54 publications

(46 citation statements)

References 15 publications

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“…Therefore we dissolved For closer consideration we calculated the molecular weight distributions of the SAN-subchains of the PS-SAN block copolymers by means of Equation (3), according to Tanaka et al [19] In Equation (3) …”

Section: Resultsmentioning

confidence: 99%

Acetic Anhydride - Accelerating Agent for Nitroxide-Controlled Free-Radical Copolymerization of Styrene and Acrylonitrile

Baumann

Schmidt‐Naake²

2001

Macromol. Chem. Phys.

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The stereoselective hydrogenation of oxazolidinone‐substituted pyridines shown in the cover picture gives piperidines containing up to four new stereocenters. One of the biologically active compounds readily accessible by this method is (S)‐coniine, the poisonous hemlock alkaloid used in ancient Greece for executions. The famous painting by David shows Socrates shortly before drinking from the poison chalice. F. Glorius et al. describe this synthetic method on pages 2850 ff.

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Section: Resultsmentioning

confidence: 99%

Acetic Anhydride - Accelerating Agent for Nitroxide-Controlled Free-Radical Copolymerization of Styrene and Acrylonitrile

Baumann

Schmidt‐Naake²

2001

Macromol. Chem. Phys.

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“…If this sample solution were injected 13 min after the start of the gradient, then all the copolymers would appear at the interstitial volume V,, because no adsorption would occur on the surface of silica gel in advance. Figure 6 ends at V, 9 and a baseline still declines somewhat. Actually, it became level at V, 11 mL and the difference of W absorbance between V, 9 and 11 mL was 0.0016 absorbance units.…”

Section: Chemical Heterogeneity Of Samplesmentioning

confidence: 89%

Separation and characterization of low‐conversion poly(styrene‐co‐methyl methacrylate) by liquid adsorption chromatography

Mori

Uno

1987

J of Applied Polymer Sci

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SynopsisPoly(styrene-co-methyl methacrylate) copolymers of narrow chemical composition distributions were separated according to composition by linear gradient elution at column temperatures between 10 and 80°C using silica gel as an adsorbent. The initial mobile phase was a mixture of chloroform and ethanol (99.0 : 1.0, v/v) and the final one (95.5 : 4.5). The relationship of retention volume and the composition of the copolymers was obtained. Higher column temperature (and/or less ethanol content in the mobile phase) is preferable for the separation of copolymers having less MMA and vice versa. Molecular weight dependence on retention volume was not observed. The chromatographed copolymers were still chemical heterogeneous: the compositional difference of the front and rear halves of an adsorption chromatogram of a copolymer was 2.1%. The front half had a higher styrene content and lower molecular weight averages than those for the rear half of the peak. This separation method was reproducible and the relative standard deviation was about 0.6%. Recovery of fractions was 98.2% by isocratic elution and 96.4% by gradient elution.

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“…Besides the aforementioned chlorinated polyethylene, we recently demonstrated gradient separations at CPA (including gradient elution on zirconiabased columns at high temperature) of ethylene-acrylate and ethylene-vinyl acetate copolymers obtained in tubular and autoclave reactors [12]. We believe that the majority of successful separations of statistical copolymers by chemical composition reported in literature starting with the pioneer works of Tanaka et al [13], Mori et al [14] and Morey [15] were actually achieved by gradient elution at CPA. But the separation by chemical composition is not the only possible application of this technique.…”

Section: Introductionmentioning

confidence: 95%

Characterization of synthetic copolymers by interaction polymer chromatography: Separation by microstructure

Brun

Foster

2010

J of Separation Science

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Gradient elution of synthetic polymers has been studied both theoretically and experimentally using normal and reversed-phase HPLC systems. An accurate equation describing the gradient elution of polymer-homologous series in the context of continuous random-flight model of a flexible polymer chain interacting with attractive surface of the porous material has been derived and experimentally verified against a series of narrow polystyrene standards. Both the theory and the experiment predict the existence of molar mass-independent gradient elution at critical point of adsorption (CPA). The extension of the theory to synthetic copolymers predicts the existence of the CPA for statistical copolymers and describes its dependence on chemical composition and microstructure (blockiness) of the polymer chains. One of the important theoretical conclusions is that blockiness always increases the retention, so that blockier polymer chains elute later than their more random counterparts with the same chemical composition. This prediction has been confirmed experimentally using block and statistical styrene-methylmethacrylate copolymers. Block copolymers do not have CPA and always elute between critical points of the corresponding homopolymers. The retention depends on the polymer molar mass and increases with the length of the blocks from a stronger absorbing monomer. These findings provide theoretical and experimental bases for separation of statistical and block copolymers by chemical composition and microstructure of polymer chains.

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Composition and molecular weight distribution of block copolymers

Cited by 54 publications

References 15 publications

Acetic Anhydride - Accelerating Agent for Nitroxide-Controlled Free-Radical Copolymerization of Styrene and Acrylonitrile

Acetic Anhydride - Accelerating Agent for Nitroxide-Controlled Free-Radical Copolymerization of Styrene and Acrylonitrile

Separation and characterization of low‐conversion poly(styrene‐co‐methyl methacrylate) by liquid adsorption chromatography

Characterization of synthetic copolymers by interaction polymer chromatography: Separation by microstructure

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