We achieve a donut-like polystyrene (PS) latex structure in a dispersion polymerization system where a low dose of octavinyl polyhedral oligomeric silsesquioxane (OVPOSS) is essential for inducing the asymmetric growth of latex particles. The evolution of donut shape is sensitive to polarity of dispersion medium, monomer conversion and substituted group of styrenic monomer. This asymmetric growth originates from the attaching of OVPOSS oligomers, i.e. nanoblocks (NB), to the surface of early PS particles, which launches a colony on each particle. Subsequent anchoring of OVPOSS surrounding the colony leads to a spread of NB, which concurrently impedes the growth of PS latex over the area they settle. While the uncovered patch continues expanding through propagation of PS radical chains, the region with a spreading of NB is consequently transformed to a concave thermosetting cap on a portion of individual PS particles. This anisotropic structure demonstrates unique viscoelastic characteristic shown by the latex films prepared. (C) 2016 Elsevier Ltd. All rights reserved.