In order to get a quantitative method to predict and control the composite latex particle morphologies in seeded emulsion polymerization, a model system consisting of two polymer particles (P_a and P_b) and continuous phase of water was used to simulate the seeded emulsion polymerization system, and a thermodynamic analysis was conducted for three possible extreme morphologies of composite latex particles under the condition where kinetic factors were not considered. The results showed that the final stable latex particle morphology was controlled not only by interfacial tensions (γ_(aw), γ _(bw) and γ_(ab)) between three phases (polymer A, polymer B and water) , but also by the fraction volumes (V_a and V_b) of the two polymers. The thermodynamic requisites for the formation of P_a/P_b core/shell latex particle were (γ_(aw)-γ_(bw))/γ_(ab) > V_a~(2/3)-V_b~(2/3) and (γ_(aw)-γ_(ab))/γ_(bw) > (1-V_b~(2/3))/V_a~(2/3); and those for the formation of P_a/P_b core/shell latex particle were (γ_(aw)-γ_ (bw))/γ_(ab) < V_a~(2/3)-V_b~(2/3) and (γ_(bw)-γ_(ab))/γ_(aw) > (1- V_a~(2/3))/V_b~(2/3). When acrylate-silicone seeded emulsion polymerization system was used to test these relationships, preliminary experiment investigated that the particle morphology is basically agreement with the prediction results of thermodynamic analysis.

Key words: EMULSION POLYMERIZATION, LATEX, THERMODYNAMIC ANALYSIS, POLYACRYLATE, SILOXANE