Chemical structure of different celluloses derivatives. A. Cellulose consists of glucose saccharides connected through glycosidic 1–4 bonds. In the generation of cellulose derivatives hydrogen atoms (annotated as R) on three hydroxyl groups on each glucose unit are susceptible to chemical derivatization. The possible substitutions for hydroxypropyl methylcellulose (HPMC), methylcellulose (MC), hydroxypropyl cellulose (HPC), hydroxyethyl cellulose (HEC) and carboxymethyl cellulose (CMC) are shown. B. Schematic illustration of substitution patterns in homogenously and heterogeneously substituted cellulose.