SEC Absolute Molar Mass Detection by Online Membrane Osmometry

Abstract

A membrane osmometer with a short response time based on a previously developed concentric design with a capillary-shaped membrane has been applied as an online SEC detector for absolute molar mass detection in combination with a concentration detector. The flow cell volume is 12.2 µL, the response time approximately 15 s, and the molar mass cutoff is below 5 kg/mol. The performance has been tested with polystyrene standards in toluene under realistic SEC conditions.

Theory of Multiple‐Detection Size‐Exclusion Chromatography of Complex Branched Polymers

“…We now develop the new formalism, first for the case of linear polymers and then for branched ones. Account is taken of the variety of different detectors in current and potential use: those which are sensitive to the number of polymer chains eluting at a given elution time (such as UV or fluorescent detection where each chain bears a single fluorophore), to their mass (refractive index detector, UV when sensitive to the monomer unit), to a product of mass and a size-related parameter (viscometric detection, online osmometry, [30] LS), to their molar mass (NMR for oligomers [29] ) and to their composition or tacticity (NMR [29,34] ). The branching level could also be determined by SEC-NMR, especially in the case of hyperbranched polymers, which exhibit a high branching level.…”

Polyacrylonitrile capillary membranes for membrane osmometry

“…Despite the reduced solvent permeability, response times of the membrane osmometer below 15 s can be achieved, which even allows for the application as an absolute molecular weight detector for size exclusion chromatography [14]. …”

“…Their main advantage is, however, an up to 20 times lower molecular weight cutoff. In this paper the preparation, characterization, and assessment of PAN membranes in connection with the new concentric osmometer design [5,14] will be presented.…”

Photocrosslinkable Star Polymers: Precursors for Model Polyelectrolyte Networks

“…Membrane osmometry measurements were carried out in toluene at room temperature with an osmometer developed at this institute. [41] Vapour pressure osmometry measurements were performed on an osmometer from Wescan (Model 232 A).…”