AbstractThe multi‐component polymerization of the industrially important hydrophobic and hydrophilic monomers exhibits special features in comparison to the multi‐component emulsion polymerization of hydrophobic monomers. The main difference stems from the partial or total solubility of the hydrophilic monomer in the continuous water phase and in some instances also from the formation of water‐soluble polymer. The chemical and morphological structure of the polymer particles, beside the comonomer partitioning between water and oil phases, is governed also by the reactivity ratios of comonomer pair and by the extent of the mutual miscibility or phase separation of polymeric material of the particle. Compositional (chemical) heterogeneity of the polymer particles is also influenced by different affinity of the polymer (copolymer) to the water and oil phases. Structurally inhomogeneous polymer product results from the simultaneously proceeding polymerization in the water and oil phases. The polymer product represents a mixture of homopolymer (copolymer) formed in the water phase and of the copolymer (sometimes graft copolymer) formed on the surface of the polymer particles or in the interphase surrounding the polymer par