The Preparation And Morphology Study Of Styrene-Acrylic Composite Latex Particles

Many practical benefits obtained by the special morphology of composite latex particles are superior to those of their homopolymers.In order to improve the emulsion properties,contact angle method is introduced to semi-qualitatively forecast the thermodynamic equilibrium morphology under polymerization conditions.The contact method provide a more economical,efficient way to understand the composite latex particles' final morpholoy.Fix on the research systems are PSt/PMMA,PMMA/PSt,PMMA/P(BA-co-St) and P(MA-co-MMA)/PSt.Ascertain the optimum experiment conditions through orthogonal experiment method:the seed emusion is produced by flow-state semi-continuous polymerization.The temperature of seed polymerization is 73℃, stirring rate 200r/min,the amount of emulsifier is 1.5%with total monomer.The temperature of second-step polymeriztion is 70℃,the monomer adding rate of staved-state polymeriztion is 5～6d/min(about 0.25g/min),the total time of monomer swelling is 24h.According to the polymer phase interfacial tension calculated by Sundberg Gibbs free energy chance model,the thermodynamic equilibrium morphology would be obtained,it's core-shell for PSt/PMMA,and inverted core-shell for PMMA/PSt, PMMA/P(BA-St),P(MA-co-MMA)/PSt.The thermodynamic equilibrium morphology provides a quantitative reference for the corresponding system of preparation of the composite latex partice morphology.Based on the calculation in accordance with theoretial values,measures the polymers contact angles of deionized water and iodomethane,and the changes of phases interfacial tension can be deduced.The thermodynamic equilibrium morphology of PMMA/P(BA-St) in pace with the increase of BA transit hemisphere to inverted core-shell.The thermodynamic equilibrium morphology of P(MA-MMA)/PSt is inverted core-shell when the proportions between MA and MMA are 10:90 and 20:80.It turns to hemisphere when the proportions are 30:70 and 40:60.The contact angle reflects the authentic phase interfacial tension,hence,the accuracy of morphology prediction could be enhanced.The method of contact angle could be a suitable reference for the final morphology of composite latex particles when the rate of polymerization is less than the one of polymerⅡchains' migration.