Water‐soluble starch derivatives containing quarternary ammonium groups of high degree of substitution are prepared by reacting starch with 2,3‐epoxypropyltrimethylammonium chloride in different reaction media. The reaction was carried out in aqueous sodium hydroxide under dissolution of the product, in dimethyl sulfoxide homogeneously, and completely heterogeneously in ethanol/water. The DS values of up to 1.1 in an one‐step synthesis of the samples can be controlled by adjusting the molar ratio of cationization agent to anhydroglucose unit and are only slightly dependent on the amylose content of the starting starch material. A two‐step reaction yields products of a DS of up to 1.5. The structure of the cationic starch derivatives was confirmed by means of elemental analysis, FTIR‐ and NMR spectroscopy as well as GC‐MS.

Amphiphilic starch derivatives of high degree of substitution (DS) were prepared by benzylation of pea, potato and waxy maize starch followed by the introduction of hydroxypropyltrimethylammonium and carboxymethyl moieties. The conversions were carried out under heterogeneous conditions leading to products with a total DS of up to 1.8. The starch composition regarding amylose and amylopectin influences the DS value. The structure of the products was characterized by means of elemental analysis, FTIR and NMR spectroscopy, and, in case of benzyl carboxymethyl starch by means of HPLC after complete chain degradation. The tensioactive properties depend on the DS values of hydrophilic and lipophilic groups and can be adjusted by controlling the molar ratio anhydroglucose unit to reagent during the synthesis. Surface tensions as low as 48.6 mN/m were found for benzyl hydroxypropyltrimethylammonium starch and 38.6 mN/m for benzyl carboxymethyl starch. The lowest critical micelle concentration determined is 2.1 mmol/L.