Determination of the substituent distribution along cellulose acetate chains as revealed by enzymatic and chemical methods

Eight cellulose acetate samples with degree of substitution (DS) in the range from 0.4 to 2.7 were characterised regarding their DS, substituent distribution in the anhydroglucose units, molar mass distribution and intrinsic viscosity. Samples were intensively hydrolyzed with a purified endoglucanase and the degradation monitored by analytical size exclusion chromatography (SEC). A preparative SEC system using pyridine:water was developed, suitable for the analysis of samples over a wide range of DS. Two methods were established to determine the DS in milligram scale for further analysis of isolated fragments. For cellulose acetate samples with DS 0.4, 0.7 and 1.2 endoglucanase fragmentation followed by preparative chromatography and analysis of isolated fragments was performed. The procedure was suitable to determine differences in the substituent distribution along the polymeric chain of cellulose acetates susceptible to endoglucanase hydrolysis.