Polystyrene latexes were prepared in the presence of an amino-containing functional comonomer, i.e. N-(3-aminopropyl) methacrylamide hydrochloride (APMH), via soap-free batch emulsion polymerization initiated by the cationic initiator 2,2'-azobis (2-amidino propane) di-hydrochloride (V50). These latexes were characterized through studying the influence of ionic comonomers on the polymerization kinetics, particle size, surface charge density and colloidal properties. The synthesized latexes were monodisperse with a final size between 100 and 600 nm depending on the APMH concentration. The initial polymerization rate and the particles number increased in accordance with the Smith-Ewart theory for soap-free styrene emulsion polymerization with a hydrophilic functional comonomer. The final functionalization rate of the particles has been particularly studied with the intention of fitting the prepared latexes to be utilized in the immobilization of biological molecules for biological sample preparation and diagnostic applications. This article is protected by copyright. All rights reserved.