GRAFT-COPOLYMERS HAVING A HYDROPHOBIC BACKBONE AND HYDROPHILIC BRANCHES .9. PREPARATION OF WATER-DISPERSIBLE MICROSPHERES HAVING POLYCATIONIC BRANCHES ON THEIR SURFACES

Cationic microspheres were prepared by dispersion copolymerization of poly(4-vinyl-N-n-butylpyridonium bromide) (P4VBuPBr) macromonomer with styrene in an ethanol-water mixture without any emulsifier. The monom er reactivity ratio, r(2), for the copolymerization of the macromonome r (M(1)) with styrene (M(2)) in the heterogeneous system was smaller t han that in the homogeneous system. ESCA analysis of the microsphere s urfaces suggests that their surfaces are covered with hydrophilic P4VB uPBr chains. The particle size of the microspheres decreased with incr easing molecular weight of the macromonomer. The results on measuring the turbidity of the microsphere suspension suggest that its water dis persibility depends strongly on the ionic strength.