The interaction of acid comonomers, crotonic acid, maleic monoesters, maleic acid with the surfactant, the sodium salt of sulfosuccinic acid semiester with nonyl phenol etoxylated with 25 moles ethylene oxide (NPEO25SS) depends on the hydrophilicity of comonomers. The rate of initiator splitting reaction (potassium persulfate - KPS) in presence of NPEO25SS and of comonomers decreases with the increasing of acid comonomer concentration. This rule is valid in copolymerization of acid comonomers with vinyl acetate (VAc) below a small comonomer concentration, then the rate increases. The presence of some more hydrophobic comonomers maleic diesters, lowers the decomposition rate of KPS. These results are the effect of the stronger interaction of NPEO25SS with more hydrophobic polymer particles. In their presence the concentration of free NPEO25SS is lower and it can participate in the KPS - surfactant reaction and rise its rate to a lesser extent. Owing to some secondary acid comonomer - KPS reactions the productivity of initiator splitting decreases with acid comonomer concentration The glass transition temperatures of the thin films obtained in presence of acid comonomers, may increase or decrease, depending on the volume of the substituents of these comonomers.