Determination of the structural parameters of aqueous polymer solutions in the molecular, partially aggregated, and particulate states by means of FFFF/MALLS

Flow field-flow fractionation (FFFF) has a separation range from ≈104 to 1012 g mol−1 in terms of molar mass and only requires that the sample be soluble (or dispersable) in some carrier liquid. By coupling this technique with a multiangle laser light-scattering photometer (MALLS), it becomes possible to obtain the absolute distributions of the molar mass and radii of gyration in addition to the distribution of the hydrodynamic radii. The required information on the polymer shape and solution structure can then be derived from these data. The coupling of FFFF/MALLS has proven to be a powerful method for characterizing aqueous systems; one of the reasons for this was the introduction of a circulating cross flow. The scope for applying this new analytical technique is illustrated by means of homogeneously dissolved polymer molecules (dextran), cationic polyelectrolytes (poly-diallyldimethylammonium chloride), particulate systems (latices, albumin, and tobacco mosaic virus), and solutions containing partially aggregated molecules (pectin solutions) within a molar mass range from MW=8×104 g mol−1 to MW=2×107 g mol−1.