Characterization of cellulose and cellulose derivatives by SEC

For many years SEC (size exclusion chromatography) has been a well established method to determine the molecular weight distribution of polymers. Particulary characterization of the molecular weight distribution of cellulose is mostly be done with the corresponding nitrates and carbanitates. An alternative method is given by dissolving cellulose directly in dimethylacetamide/LiCl and analysed by SEC. In comparison of these methods the advantages and disadvantages are discussed. The determination of the substituents of cellulose derivatives is a special problem especially when the substituent does not give other:detectable signals than cellulose. Using a second derivatisation of the free OH-groups by Substituents giving a special signal (UV, fluorescence) the distribution of the primary substituents in dependence of the M-w of the cellulose chains may be determined.