Detailed investigation on the molecular structure of carboxymethyl cellulose with unusual substitution pattern by means of an enzyme-supported analysis

Four carboxymethyl cellulose samples derived from the synthesis concept of "reaction in reactive microstructures" were characterised in detail by comb ination of different analytical techniques. Fractionation of one of the sam ples according to water-solubility into four fractions revealed that a non- statistical distribution of the substituents occurred for all fractions. En doglucanase fragmentation of three samples was performed followed by analyt ical and preparative SEC. The multi-detected analytical SEC proved samples of high degree of substitution up to 1.9 to be intensively degraded, suppor ting the proposed block-like substitution pattern. The detailed investigati on of soluble fragmentation products by preparative SEC, hydrolysis and ani on exchange chromatography pulsed amperometric detection revealed that all samples contain fragments of much higher DS values than the average DS of t he starting material. On the other hand, high quantities of degradation pro ducts of low DS or almost no substitution occurred. Therefore, a structure can be proposed with segments of very high DS alternating with areas of lim ited substitution. The result clearly showed that the high substituted frag ments were dominated by 2,3,6-tri-O-CMG.