New, strong cationic hydrogels: Preparation of N,N,N′,N′-tetraallyl piperazinium dibromide and its copolymers with N,N-diallyl morpholinium bromide

N,N,N′,N′-tetraallyl piperazinium dibromide (TAP) has been prepared in high yields by quaternization of N,N′-diallyl piperazine with allyl bromide. Herein, we have described preparation of nonhydrolyzable, strong, cationic hydrogels by copolymerization of TAP with N,N-diallyl morpholinium bromide (DAM) in the presence of t-butyl hydroperoxide as initiator in aqueous solutions. Because the monomer and crosslinker involved consist of quaternary amine functions, these hydrogels are fully cationic and do not carry hydrolyzable groups. Contrary to expectations, the quaternary amine hydrogels presented do not show any super absorbency, instead dry gel particles in water undergo spontaneous disintegration with an audible bursting of the particles due to instantaneous, high osmotic pressure. Whereas, in KBr or HBr solutions, the swellings are relatively slow.