Detection Orthogonality in Macromolecular Separations: Role of the On-Line Viscometer in Characterizing Polymers at Conditions of “Spectroscopic Invisibility”

Published on Apr 18, 2015in Chromatographia2.044
· DOI :10.1007/S10337-015-2898-7
André M. Striegel25
Estimated H-index: 25
(NIST: National Institute of Standards and Technology),
Leena Pitkänen18
Estimated H-index: 18
(NIST: National Institute of Standards and Technology)
Sources
Abstract
Much has been written over the last two decades about the advantages of separation orthogonality for the characterization of complex polymers and blends, and of the additive and synergistic benefits of combining various physical and chemical detection methods in the determination of molar mass, chemical heterogeneity, dilute solution conformation, etc. Less attention has been paid to the complementarity of detection methods that are truly orthogonal to each other with respect to a given property. A common, yet particularly different type of macromolecular liquid chromatography detector is the on-line viscometer, as its measurement principle is based on hydrodynamic transport properties, thus separating it from the large variety of spectroscopically based detectors. Here, we explore how the on-line viscometer can provide insights into the size-exclusion chromatographic analysis of individual homopolymer samples and of blends, even in cases where no response is observed with commonly employed detectors such as on-line refractometry and static and quasi-elastic light scattering, i.e., when analyses are conducted at conditions of “spectroscopic invisibility”.
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References19
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#1Leena Pitkänen (NIST: National Institute of Standards and Technology)H-Index: 18
#2André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
Asymmetric flow field-flow fractionation (AF4) coupled with multi-angle static and quasi-elastic light scattering and differential refractive index detectors, was employed for the separation and characterization of regular star-shaped polystyrenes and their linear and span analogs in tetrahydrofuran. Stars with different arm lengths were separated from each other by employing a binary slope cross-flow gradient. Cross-flow optimization enabled fast separation of polystyrenes in two- and three-com...
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#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
Abstract Flow-induced, on-column degradation is a major hindrance to the accurate characterization of ultra-high molar mass macromolecules and colloids. This degradation is a direct result of the large shear rates which are generated within the column, which cause chain scission to occur both in the interstitial medium and, it has been postulated, at the packing particle pore boundary. An additional putative source of degradation has been the column frits, though little experimental evidence exi...
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#1Mallory J. Morris (FSU: Florida State University)H-Index: 3
#2André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
a b s t r a c t Introduced here is a method for determining the solution conformational entropy of oligosaccharides (−� S) that relies on the on-line coupling of size-exclusion chromatography (SEC), an entropically- controlled separation technique, and differential viscometry (VISC). Results from this SEC/VISC method were compared, for the same injections of the same sample dissolutions and under identical sol- vent/temperature conditions, to results from a benchmark SEC/differential refractomet...
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#1W. RadkeH-Index: 1
#2Jana Falkenhagen (BAM: Bundesanstalt für Materialforschung und -prüfung)H-Index: 21
In the last decade, the use of interaction chromatography and hyphenated techniques has become increasingly important for the characterization of polymeric materials. Interaction chromatography allows separation by other structural features than molar mass, while hyphenation with mass spectroscopy or spectroscopic techniques provides detailed characterization of the separated chromatographic fractions. This chapter gives an overview of the principles and applications of interaction chromatograph...
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#1Salvatore FanaliH-Index: 64
#2Paul R. HaddadH-Index: 73
Last. David LloydH-Index: 2
view all 5 authors...
This is a single source of authoritative information on all aspects of the practice of modern liquid chromatography suitable for advanced students and professionals working in a laboratory or managerial capacity. It includes chapters that are written by authoritative and visionary experts in the field provide an overview and focused treatment of a single topic. It includes comprehensive coverage of modern liquid chromatography from theory, to methods, to selected applications. Thorough selected ...
#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
Abstract Over the past half century, size-exclusion chromatography (SEC) has become the premier method by which to determine the molar mass (M) averages and the molar mass distribution (MMD) of natural and synthetic macromolecules. When coupled to a multiplicity of detection methods, SEC also has the ability to inform our knowledge of the physicochemical properties of polymers. This chapter provides an introduction and overview to the fundamental aspects of SEC, as appertain chromatographic rete...
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#1Salvatore FanaliH-Index: 64
#2Paul R. Haddad (UTAS: University of Tasmania)H-Index: 73
Last. David LloydH-Index: 2
view all 5 authors...
This is a single source of authoritative information on all aspects of the practice of modern liquid chromatography suitable for advanced students and professionals working in a laboratory or managerial capacity. It features chapters that are written by authoritative and visionary experts in the field provide an overview and focused treatment of a single topic. Each chapter emphasizes the integration of chromatographic methods and sample preparation, automation, and explains how liquid chromatog...
#1Amandaa K. Brewer (FSU: Florida State University)H-Index: 6
#2André M. Striegel (FSU: Florida State University)H-Index: 25
The ability to characterize the size and shape distributions of broadly polydisperse analytes is a driving force in particle size analysis. Multi-detector hydrodynamic chromatography (HDC), which has previously shown promise in its ability to characterize the size and shape of monodisperse, spherical polystyrene latex standards, is applied here to include the characterization of bi-, tri-, and tetramodal latex blends and their constituents varying in size, chemistry, and compactness. The ability...
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#1Michelle J. Smith (FSU: Florida State University)H-Index: 8
#2Imad A. Haidar (FSU: Florida State University)H-Index: 1
Last. André M. Striegel (FSU: Florida State University)H-Index: 25
view all 3 authors...
The concept of ‘size’ in polymer science can have several interpretations, including definitions that rely on either statistical or equivalent-hard-sphere measures of the spatial extent of macromolecules in solution. A definition such as that of the equivalent thermodynamic radius (RT), which relies on the second virial coefficient of the polymer solution, offers the possibility of a zero or even a negative size parameter for macromolecules, depending on whether the polymer solution is in a thet...
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Cited By4
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#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
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#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
#2Walter B. Wilson (NIST: National Institute of Standards and Technology)H-Index: 14
Last. Lane C. Sander (NIST: National Institute of Standards and Technology)H-Index: 64
view all 3 authors...
We continue herein the exploration of detector orthogonality in size-based macromolecular separations. Previously [5], the sensitivity of viscometric detection was juxtaposed to that of differential refractometry (DRI) and light scattering (LS, both static and dynamic), and it was shown that viscometry is a truly orthogonal detection method to both DRI and LS. Here, via the size-exclusion chromatography (SEC) analysis of blends of polystyrene and poly(methyl methacrylate), we demonstrate the ort...
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#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
The specific refractive index increment (∂n/∂c) is an essential datum for the accurate quantitation of molar mass averages and distributions (inter alia) of macromolecules when refractometry, static light scattering, and/or viscometry detection are coupled on-line to size-based separation techniques. The latter include methods such as size-exclusion and hydrodynamic chromatography, and asymmetric and hollow-fiber flow field-flow fractionation. The ∂n/∂c is also needed for accurate determination ...
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#1André M. Striegel (NIST: National Institute of Standards and Technology)H-Index: 25
Size-exclusion chromatography (SEC) has benefitted from commercially available on-line viscometers for 30 years now. Initial (and continued) interest was mostly in applying the universal calibration concept to obtain molar mass averages and distributions of macromolecules for which no appropriate calibration standards existed, and in obtaining long-chain branching information such as branching number and frequency. During the last three decades, viscometry has shown itself to be able to do much ...
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