Dusan Berek
Polymer Institute, Slovak Academy of Sciences, Slovakia
Title: Progress in liquid chromatography of synthetic polymers
Biography
Biography: Dusan Berek
Abstract
High performance liquid chromatographic (HPLC) methods represent the most important tool for molecular
characterization of synthetic polymers. Mean molar masses and molar mass distributions of linear and branched homopolymers
are easily determined by size exclusion/gel permeation chromatography (SEC/GPC). As by-products, several other
useful data can be assessed with SEC/GPC. Recent progress in SEC/GPC comprises improved instrumental hardware and data
processing procedures. High sample throughput of the ultra-fast SEC/GPC allows acceleration of analyses, which is especially
important in combinatorial material chemistry and in production control. Still, further improvements of the SEC/GPC method
are needed, which include its hardware, especially columns and detectors, and also standardization of sample preparation,
measurements, and data processing. SEC/GPC exhibits excellent intra-laboratory repeatability, which evokes a notion of its
high reliability. Recent series of the round robin tests, however, revealed surprisingly poor inter-laboratory reproducibility
of results. Evidently, accuracy of many SEC/GPC results may be rather limited. In most cases, SEC/GPC does not enable
precise molecular characterization of complex polymer systems, which possess more than one distribution in their molecular
characteristics. Typically, polymer mixtures, copolymers and functional polymers exhibit besides molar mass distribution also
distribution in their chemical structure while e.g. stereo-regular polymer species show also molecular architecture distribution.
To assess above distributions, new HPLC procedures are developed. Th ese are based on the controlled combinations of entropic
(exclusion) and enthalpic (interaction) retention mechanisms within the same HPLC column or in a series of independent
separation systems. Th ese approaches are denoted as “coupled polymer HPLC” and “two-, or multi-dimensional polymer
HPLC”, respectively. Enthalpic retention mechanisms in HPLC of synthetic polymers include adsorption, partition, phase
separation and ionic eff ects. We shall review recent progress and also problems in SEC/GPC, as well