Preparation Of PDMS/PS Nanocomposites By Emulsion And Suspension In Situ Polymerization

Nanocomposites are a new kind of materials. Nanophase and traditionalcomposite materials have obvious difference in structure and performance, such aselectrical, optical, calorific, enhanced mechanical properties. It not only pioneers anew field for polymer modification, but also supplies a new approach for fabricationand synthesis of functional polymeric organic-inorganic nanocomposites. A newpolymerization method, emulsion and suspension in situ polymerization, is reportedin this article. This method need not the posttreatment of emulsion, and adjustingsome reaction conditions directly carries out the suspension polymerization. Themethod can reduce the cost of products, reform the coagulation of nanoparticles andproduce high performance polystyrene.In Chapter two, monodisperse polydimethylsiloxane/polystyrene (PDMS/PS)core-shell microspheres were obtained via surface grafting and seeded emulsionpolymerization. The diameter of PDMS latexes was mainly determined by varyingthe ratio of sodium dodecylbenzen sulfonate (SDBS) /octamethyl cylcotertrasiloxane(D4) and the amount of H2SO4 in the polymerization. Then the PDMS latexesgrafted by methacryloxypropyl trimethoxysilane (MATS) were synthesized andconfirmed by Fourier-transform infrared spectroscopy (FTIR) andphotoncorrelation spectroscopy. Monodisperse PDMS/PS core-shell microsphereswith grafted PDMS as seed were prepared by controlling the concentration ofsurfactant and the dripping rate of monomer styrene. The results of elementalanalysis (EA) showed that not all monomer styrene connected with grafted PDMSand a few of polymer chains were twined around the core particles.In Chapter three, the prepared process of PDMS/PS composite materials wasstudied. The PDMS/PS composites by emulsion and suspension in situpolymerization were first prepared. Core-shell emulsion particle content andtransmittance were discussed. The plot of emulsion breaking was protracted by theresearch of the relationship between the process of core-shell emulsion breaking andthe electrolyte concentration. In the reaction process, PDMS/PS emulsion particlesneed not a complex course such as the breaking of emulsion, the washing ofemulsion particles and the drying of products compared with other reported methods.The composites of PDMS/PS core-shell emulsion and polystyrene were successfullysynthesized by emulsion and suspension in situ polymerization. The method ofemulsion polymerization and suspension polymerization combined in situ isfeasible.In Chapter four, the PDMS/PS composites were successfully synthesized byemulsion and suspension in situ polymerization. Polydimethylsiloxane soft particleswere uniformly dispersed in the composites and microtome section was obtained byusing transmission electron microscopy. The diameter of composite beads wasanalyzed. Finally, the properties of the film, such as water absorption ratio, contactangle, pendulum hardness and transparency were tested. The results showed that thecontent of emulsion had effects on the properties of the film.In conclusion, the method of emulsion polymerization and suspension in situpolymerization is feasible. The method can overcome the problem of complicatedposttreatment of products, and nanoparticles are dispersed in the composites and notcoagulation. So the new polymerization method has many advantages such as simpleprepared techniques, easy designing the structure and performance of polymers andhas potential applications in many fields.