Non-size-exclusion Chromatography Analysis of Synthetic Polymers
Polymers and Rubbers
Published Online: 15 DEC 2010
Copyright © 2000 John Wiley & Sons, Ltd. All rights reserved.
Encyclopedia of Analytical Chemistry
How to Cite
Lee, W. and Chang, T. 2010. Non-size-exclusion Chromatography Analysis of Synthetic Polymers. Encyclopedia of Analytical Chemistry. .
- Published Online: 15 DEC 2010
While nature is capable of producing uniform macromolecules as found in complex biosystems, man-made polymers are hardly homogeneous. They exhibit inherent distributions at least in molecular weight, and often come with multivariate distributions in chemical composition, functionality microstructure, chain architecture, and so on. Size-exclusion chromatography (SEC) has been the most widely employed chromatographic technique for the characterization of molecular weight and its distribution of synthetic polymers since its inception about half a century ago. Compared to conventional molecular weight characterization methods, SEC is an excellent method with regard to precision, analysis speed, required amount of samples, etc. Nonetheless, SEC separates the polymer molecules in terms of their chain size, which is not only a function of molecular weight but also depends on other molecular characteristics such as composition, branching, and microstructure. Therefore, SEC cannot characterize nonlinear polymers or copolymers effectively. In contrast to SEC, in which the different pore accessibility of the macromolecules is the major separation mechanism, interaction chromatography (IC) fractionates the polymer sample by enthalpic interaction between the polymer solutes and the stationary phase. As a result, IC is sensitive to the chemical nature as well as the molecular weight of the polymers, whereas it is less sensitive to long-chain branching than SEC. By judiciously selecting the IC separation condition, one can characterize specific molecular properties of polymers with much higher resolution than SEC. Furthermore, one can access the chromatographic critical condition (CC) for a given polymer system by adjusting the solute interaction strength with the stationary phase until the exclusion and interaction contributions to the solute retention are exactly compensated. Liquid chromatography at the critical condition (LCCC) can be used as a unique tool for the characterization of polymers. Of late, 2D liquid chromatography (LC) separations by a rational combination of SEC, IC, and LCCC has become more and more popular for the characterization of multivariate polymers. In this article, recent advances in non-SEC analysis methods of a variety of synthetic polymers are reviewed.
- interaction chromatography;
- chromatographic critical condition;
- two-dimensional chromatography;
- polymer characterization