Abstract
The most important items in polymer analysis are the molecular weight {and molecular weight distribution (MWD)} and the chemical composition {and chemical-composition distribution (CCD)}. High-performance liquid chromatography (HPLC) can be used to determine these items. Size exclusion chromatography (SEC) is used to measure the molecular weight and MWD. In order to obtain accurate and precise values of these parameters, problems associated with a calibration curve, abscissa (retention volume) and ordinate (detector response) must be carefully considered. Especially, since the fluctuation of abscissa by secondary effects for polar and ionic polymers is considerably large, it is required to clarify the relationship between the molecular weight and the molecular size by using a light-scattering detector. Round-robin tests can be used to clarify several problems associated with precise and accurate measurements of the molecular weight and MWD of nonpolar polymers. Non-exclusion liquid chromatography (NELC) for polymer separation can be divided into five separation techniques: adsorption, precipitation (solubility), normal and reversed phases, orthogonal, and adsorption at a critical point. These separation techniques are reviwed, especially the liquid adsorption chromatographic method developed at our laboratory is explained in detail. The measurement of MWD and CCD by the combination of SEC and NELC is also discussed. The future prospects of polymer analysis by SEC and NELC are also considered.
