Preparation of cationic water-absorbent resin from PEI and PEO

Hydrophilic network copolymers containing poly(ethylene oxide) and polyethyleneimine blocks were prepared by cross-linking polyethyleneimine with poly(ethylene oxide) terminated at both ends with Br atoms in DMSO. The experimental results show that the network density of the copolymer and the water absorption power thereupon can be efficiently controlled by the change of the amount of DMSO in the reaction system. Further modification was obtained by converting these copolymers into quaternary ammonium salts. The resulting quaternary ammonium salts exhibit enormously enhanced water absorption power. The absorption power of these quaternary ammonium salts in several organic solvents and in aqueous solutions containing Na⁺, Ca²⁺, Mg²⁺, or Fe³⁺ was also examined.