SYNTHESIS AND CHARACTERIZATION OF BLOCK-COPOLYMERS CONTAINING CATIONIC BLOCKS

Poly(ethylene glycol)-poly(diallyldimethylammonium chloride) block cop olymers containing nearly equal number of both monomer units were synt hesized by free radical polymerization using macroazoinitiators of dif ferent molecular weights obtained from 2,2'-azoisobutyronitrile (AIBN) and poly(ethylene glycol). Characterization by elemental analysis, ge l permeation chromatography and ultracentrifugation proved the formati on of ABA-block copolymers. Furthermore, the polymers were characteriz ed by DSC and viscosimetric measurements. The block copolymers lowered the surface tension of their aqueous solutions. Cross-sectional areas A(min) of some of the polymers were calculated from surface tension v s. concentration isotherms. The results indicate the PEG-blocks to be adsorbed at the air-water interface, whereas the poly-(DADMAC)-block i s completely present in the aqueous phase. The block copolymers are po werful stabilizers in emulsion polymerization of styrene, resulting in monodisperse cationic latexes.