Synthesis And Characterization Of Polysiloxane Modified Core-shell Acyrlate Latex

Polyacrylate and polysiloxane are two sorts of important polymer materials and each ofthem has their unique properties. Polysiloxane modified core-shell acrylate latex wassynthesized by grafting polysiloxane in the shell polymerization stage of synthesizingcore-shell acrylate latex, which improved the compatibility between polysiloxane andpolyacrylate and the defect of embedded of silicon unit. The latex had excellent properties,would be widely applied in many fields.Polysiloxane modified core-shell acrylate latex was synthesized bypre-emulsificational seed emulsion polymerization with methyl methacrylate(MMA) andbutyl acrylate(BA) as monomers, acrylic acid(AA) as functional monomer, octamethylcyclotetrasiloxane(D4) and tetramethyl tetravinylcyclotetrasiloxane(VD4) as organosiloxanemonomers, dodecylbenzene sulfonic acid(DBSA) as catalyst, nonylphenolethoxylates(OP-10) and sodium dodecyl sulfate(SDS) as emulsifiers and potassiumpersulfate(KPS) as initiator. The main content of research and results are listed as follows:Firstly, the effect of the mass ratio of MMA and BA in core and shell, the mass ratio ofmonomers in core and shell, the mass ratio of emulsifier in core and shell on polymerizationand properties of acrylate latex film were studied. The latex and its film were characterizedby ATR, TEM, TG and DSC. The results showed that the core-shell acrylate latex exhibitedexcellent film forming performance, the latex film exhibited better mechanical propertiesand water resistance when the mass ratio of acrylate monomers in core and shell was 1:1,the ratio of MMA and BA was 1:2 in core and 3:1 in shell respectively, the content ofcompound emulsifier was 3%(SDS:OP-10=2:1) and the mass ratio in core and shell was 4:1respectively.Secondly, the effect of catalyst, the mass ratio of D4 and VD4 and reaction temperatureon monomer conversion of organosiloxane latex were studied. The latex was characterizedby FT-IR. The results showed that the catalytic activity of organic acid DBSA was higherthan that of inorganic acid HCl. The ring-opening activity of VD4 was lower than that of D4,the final monomer conversion of VD4 was only about 65%, while that of D4 was about 80%.The monomer conversion was enhanced by increasing reaction temperature. However, when the temperature exceeded 85℃, the change of monomer conversion was unobvious.Thirdly, the effect of the content of DBSA, VD4 and D4 on polymerization andproperties of polysiloxane modified core-shell acrylate latex film were studied. The latexand its film were characterized by ATR, TEM, TG and DSC. The results showed that waterresistance of latex film was enhanced when organic silicons was introduced. When thecontent of DBSA, VD4 and D4 was 2%, 4% and 15% respectively, monomer conversion washigher while gel rate was lower, water absorption of latex film was only 4.7%, water contactangle was 84°, the latex film had excellent mechanical properties. The latex film withpolysiloxane also exhibited better thermal stability.