Limited sample recovery in coupled methods of high-performance liquid chromatography of synthetic polymers

Berek, Dušan; Russ, A.

doi:10.2478/s11696-006-0044-6

Cited by 27 publications

(20 citation statements)

References 11 publications

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“…For low molar mass standards, low oligomers might be evaporated with the mobile phase under the stringent evaporating conditions leading to smaller peak areas compared with some of the high molar mass standards [60]. For higher molar mass standards, the so-called limited recovery of polymers could be a factor, namely, the incomplete elution of some of the injected polymers [61,62]. Previous research within our group has shown that a smaller peak for higher molar masses can also be due to changes in droplet formation as the molar mass increases.…”

Section: Resultsmentioning

confidence: 99%

Two-dimensional liquid chromatography of PDMS–PS block copolymers

2012

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In this study, liquid chromatography at critical conditions of polystyrene (PS) and polydimethylsiloxane (PDMS) is used as the first dimension for the two-dimensional analysis of polydimethylsiloxane-block-polystyrene copolymers. Comprehensive two-dimensional liquid chromatography with size exclusion chromatography as the second dimension reveals information about the molar mass distributions of all separated fractions from the first dimension. Furthermore, fractions eluting at the critical conditions were collected and subjected to analysis in the second dimension at the critical adsorption point of the other block. These fractions were analyzed by Fourier transform infrared spectroscopy to determine their chemical compositions. The combination of the above approaches and the calibration of the evaporative light scattering detector for the first-dimension analysis yield deep insights into the molecular heterogeneity of the block copolymer samples. The composition of the samples and the chemical composition of the real block copolymer are also calculated by combining the results obtained at both critical conditions.

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Section: Resultsmentioning

confidence: 99%

Two-dimensional liquid chromatography of PDMS–PS block copolymers

2012

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“…Substantial fraction of sample may stay retained in the LC CC column . Detailed studies of this occurrence revealed the fast decrease of sample recovery with the increasing polymer molar mass.…”

Section: Coupled Lc Methodsmentioning

confidence: 99%

Critical assessment of “critical” liquid chromatography of block copolymers

Berek

2016

J of Separation Science

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Brief elucidation is presented of potential difficulties the researcher can face in the course of the molecular characterization of block copolymers with help of liquid chromatography under critical conditions. The impediments include the demanding identification of critical conditions, the limited area of applicable polymer molar mass, the high sensitivity of critical conditions toward minute changes in experimental conditions including changes in the interactivity of the column packing, extensive band broadening, limited sample recovery, pressure effects, detection problems, coelution of block copolymers with their noninteractive parent homopolymers, possible effect of the noninteracting chains of block copolymers on the behavior of the interacting blocks, and role of preferential solvation of macromolecules in mixed solvents. These matters may complicate proper data evaluation and challenge the exactness of results obtained. Special attention is paid to the so far neglected phenomena of preferential solvation, which may affect not only detection of block copolymers but also their retention. The latter occurrence is demonstrated by the behavior of both poly(methyl methacrylate)s eluted from bare silica gel in a mixed eluent tetrahydrofuran plus toluene and polystyrenes eluted from silica gel C18 bonded phase with the mobile phase of tetrahydrofuran/n-hexane.

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“…LC‐CC was also employed at elevated temperature for separation of polyolefins , however the method enables efficient separation of only binary polymer systems. Both LC‐CC and EG‐LC suffer from limited sample recovery .…”

Section: Introductionmentioning

confidence: 99%

Liquid chromatography under limiting conditions of desorption 6: Separation of a four‐component polymer blend

Berek

Macová

2015

J of Separation Science

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Baseline separation was achieved of a model four-component polymer blend of polystyrene-poly(methyl methacrylate)-poly(ethylene oxide)-poly(2-vinyl pyridine) in a single chromatographic run with help of the unconventional method of liquid chromatography under limiting conditions of desorption. Narrow barriers of liquids were employed, which selectively decelerated elution of particular kinds of macromolecules. Bare silica gel was the column packing, and the eluent was a mixture of dimethylformamide/tetrahydrofuran/toluene 30:50:20 w/w/w. Barrier compositions were neat toluene, B#1, neat tetrahydrofuran, B#2, and dimethylformamide/tetrahydrofuran/toluene 15:55:30, B#3. Minor blend constituents (∼1%) could be identified, as well. The result represents a step toward the separation and molecular characterization of triblock-copolymers, many of which are expected to contain besides both parent homopolymers also the diblock chains and thus they are in fact four-component polymer blends.

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Limited sample recovery in coupled methods of high-performance liquid chromatography of synthetic polymers

Cited by 27 publications

References 11 publications

Two-dimensional liquid chromatography of PDMS–PS block copolymers

Two-dimensional liquid chromatography of PDMS–PS block copolymers

Critical assessment of “critical” liquid chromatography of block copolymers

Liquid chromatography under limiting conditions of desorption 6: Separation of a four‐component polymer blend

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