Octenylsuccinate derivatives of carboxymethyl starch -: Synthesis and properties

Carboxymethyl starch (CMS, DS(CM)0.1) was modified with octenylsuccinic anhydride in various solvent systems. Using the dimethyl sulphoxide (DMSO)/p-toluenesulphonic acid (p-Ts-OH) system, carboxymethyl starch octenylsuccinates (OS-CMS) were obtained with degrees of substitution (DS) ranging from 0.03 to 0.53 at high reaction efficiency, and characterized with regard to their molecular structure, their rheological and surface active properties. The water-soluble OS-CMS derivatives showed a pseudoplastic behavior dependent on both the DS and polymer concentration (C-p). The thickening power displayed a maximum at DS 0.14 at higher C-p (2.5 and 5.0%). In spite of the only moderate surface-tension decreasing effect of the OS-CMS derivatives, most of them exhibited excellent emulsifying, foaming and antiredeposition effects. They represent novel polysaccharide-based biosurfactants with a broad application potential.