EMULSIFIER-FREE EMULSION COPOLYMERIZATION OF STYRENE WITH 2 DIFFERENTAMINO-CONTAINING MONOMERS .2. SURFACE AND COLLOIDAL CHARACTERIZATION

The colloidal and surface properties of copolymer latex particles prep ared by batch emulsifier-free emulsion polymerization of styrene with two different amino-containing monomers (Amino Ethyl Methacrylate Hydr ochloride (AEMH) and Vinyl Benzyl Amine Hydrochloride (VBAH)), and 2,2 '-azobis(2-amidinopropane) dihydrochloride (V50) as initiator were inv estigated. The final particle size was found to decrease with increasi ng the functional monomer concentration. Different titration methods w ere used to quantify the surface amino (brought by the monomer) and am idino groups (originated from the initiator) on the latex particles. T he same behavior was observed on both type of latexes: increasing the functional monomer concentration caused the surface amino groups densi ty to increase from 0 to a plateau value at 8.2 mu C/cm(2), whereas th e surface amidino groups density decreased from 18.5 to 2 mu C/cm(2). These results were confirmed by electrophoretic measurements and they corroborated those obtained in a previous kinetic study (Part 1) conce rning the role of functional monomers as transfer agents. (C) 1997 Joh n Wiley & Sons, Inc.