Polystyrene latex particles in an emulsifier-free emulsion were prepared by purified styrene (St) as monomer and 2,2'-azobis (2-amidino propane) dihydrochloride (ABA, 2HCl) as initiator. The optimized condition of polymerization of styrene was obtained by using the various parameters such as different amounts of monomer (0.009, 0.051, and 0.071 mol styrene/mol Water), different amounts of initiator (6.02, 4.62, 2.41, and 1.00 weight percent of initiator relative to styrene), and pH (range 1-7). Quantitative and qualitative analyses of prepared polymer were performed by Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Gel Permeation Chromatography (GPC), and H-1-NMR and FT-IR spectroscopy, that were used, respectively, to show the morphology of particles, the glass transition temperature (T), the average molecular weight, and the structure of the prepared polymer. (C) 2004 Wiley Periodicals, Inc.