Synthesis of amino-functionalized latex particles by a multistep method

Cationic latex particles with surface amino groups were prepared by a multi step batch emulsion polymerization. In the first one or two steps, monodisp erse cationic latex particles to be used as the seed were synthesized, and in the third step, two different amino-functionalized monomers [aminoethylm ethacrylate hydrochloride (AEMH) and vinylbenzylamine hydrochloride (VBAH)] were used to synthesize the final functionalized latex particles. 2,2 ' -A zobisisobutyramidine dihydrochloride was used as the initiator, and differe nt concentrations of two quaternary ammonium emulsifiers with hydrophobic c hains of different lengths were examined. To characterize the final latexes yields were obtained gravimetrically, and particle size distributions and average particle diameters were determined by transmission electron microsc opy and photon correlation spectroscopy. The amount of amino groups was det ermined by fluorimetry. The effect of the amino-functional monomer used on the final latexes and the colloidal behavior of the system were studied. Th e influence of the different conditions utilized to synthesize the latexes on the colloidal stability of the particles was evaluated in terms of the F uchs stability ratio and electrophoretic mobility. High yields of the amino -functional monomers were obtained. Surface amino, amidine, and quaternary ammonium groups provided the cationic character. The colloidal stability be havior of the products obtained was compatible with their cationic characte r. (C) 2001 John Wiley & Sons, Inc.