One-step quaternization/crosslinking of starch with 3-chloro-2-hydroxypropylammonium chloride/epichlorohydrin in the presence of NH4OH

Quaternization/crosslinking of starch with 3-chloro-2-hydroxypropyltrimethyl-ammonium chloride (CHMAC)/epichlorohydrin (E) in the presence of NH4OH, NaOH and water was studied. The reaction was optimized and the products analyzed using solid-state NMR, acid-base titration methods and dye-binding tests. The solid-state NMR data in the presence of water confirmed the hydroxypropyl and trimethylammoniumhydroxypropyl groups in the obtained ion-exchanger. Although the linkage to starch could not be proved, the CH2 groups linked to nitrogen and to oxygen could be tentatively assigned. Optimal molar quantities and ratios are at starch: E:NH4OH:NaOH:H2O:CHMAC = 0.01:0.03:0.05:0.1:0.01. The exchange capacities (Q's) determined by potentiometric titration are smaller than values calculated from elemental analysis. This might be due to longer equilibrium times required for the exchange of ions, than those, which we could use on the automatic titrator. The dye binding properties are pH-dependent for the ion-exchangers containing tertiary amine groups next to quaternary ammonium groups and close to pH-independent when containing only quaternary ammonium groups (prepared in absence of NH4OH). Copyright (C) 1996 Elsevier Science Ltd.