Summary: Pressure-Sensitive Adhesives (PSAs) are used for many applications (e.g. tapes and labels), and the market is still growing as new applications are regularly discovered. Emulsion polymerization is widely used to produce water-based PSAs. In this work, the influence of morphology, diameter and acrylic acid concentration in the particles on adhesion properties (peel, tack and shear) was studied. To do so, two series of homogeneous and core-shell latex particles of poly(butyl acrylate-2-ethyl-hexyl acrylate) with different concentrations of acrylic acid (0, 1, 3 and 5 wt%) and three different average diameters, were synthesized by means of emulsion polymerization techniques. The materials were characterized by dynamic light scattering, zeta potential and transmission electronic microscopy. The contents of acrylic acid in the polymer and dispersed medium were determined and the higher quantity of it was found within the particles. The best equilibrium between adhesion properties was found in the core-shell particles with 3 wt% of AA. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.