Field-flow fractionation on poly(vinyl formamide), other polymers and colloids

(Flow-)field-flow fractionation was used for the characterization of colloidal particles. The separation according to the hydrodynamic diameter is used in the range 20–400 nm, and differences in diameter exceeding 20–30% are well recognized. The method is rather tolerant of the type and the architecture of the sample. Coupling with a light scattering and a refractive index detector gives the molar-mass distribution and the molecular radius as a function of the absolute molar mass. Dextrane and polystyrene sulfonate sodium were analyzed as a control: they are examples of branched and linear molecules. Poly(vinyl formamide) is available on a large industrial scale for paper manufacturing. Samples from that synthesis are shown to be represented by a chain architecture. In earlier examples only branched architectures were found. As examples for more complex colloidal particles, β-carotene hydrosols were analyzed using a UV—vis detector. The size distribution of the particles differs depending on the preparation process, and free protecting colloid was obtained.