, Volume 399, Issue 4, pp 1413-1423,
Open Access This content is freely available online to anyone, anywhere at any time.
Date: 22 Oct 2010

Size-exclusion chromatography (SEC) of branched polymers and polysaccharides

Abstract

Branched polymers are among the most important polymers, ranging from polyolefins to polysaccharides. Branching plays a key role in the chain dynamics. It is thus very important for application properties such as mechanical and adhesive properties and digestibility. It also plays a key role in viscous properties, and thus in the mechanism of the separation of these polymers in size-exclusion chromatography (SEC). Critically reviewing the literature, particularly on SEC of polyolefins, polyacrylates and starch, we discuss common pitfalls but also highlight some unexplored possibilities to characterize branched polymers. The presence of a few long-chain branches has been shown to lead to a poor separation in SEC, as evidenced by multiple-detection SEC or multidimensional liquid chromatography. The local dispersity can be large in that case, and the accuracy of molecular weight determination achieved by current methods is poor, although hydrodynamic volume distributions offer alternatives. In contrast, highly branched polymers do not suffer from this extensive incomplete separation in terms of molecular weight.

Figure

Representation of (a) a linear polymer chain and various branched polymer structures with (b) longchain branches (amylose-like), (c) short-chain branches (amylopectin-like), (d) both short-chain and long-chain branches (polyacrylate- or polyethylene-like).

Published in the special issue Separation Science of Macromolecules with Guest Editor André Striegel.