Preparation Of PMMA/inorganic Nanocomposites By Emulsion Polymerization

Nanocomposite materials combining the properties of high polymerand nanometer-sized materials are in the recent several years studies oneof the most widespread compounds. These materials promise applicationsin many fields such as chemical industry, electron, architecture andbiologic medicine etc. Emulsion polymerization is an important methodof preparing polymer nanocomposites. Because it possesses many meritssuch as low viscosity, quick radiating, high response speed, low cost,slight environmental pollution, simple equipment and technology, flexiblemanipulation etc, and is also hotspot of material science currently.In this paper, nano-SiO₂ and nano-ZnO were modified by surfacemodifier, and then PMMA/SiO₂ and PMMA/ZnO nanocomposites wereprepared by emulsion polymerization. It reviewed effect of differentfactors such as emulsification, monomer, initiator and time on solidcontent, success rate, percent conversion and grain size of latex. The structure and thermal behavior of nanocomposites were charactered by IR,TEM, XRD and TGA. The dispersion stability of nano-particle andcomposites was tested in organic solvent. Particle size distribution oflatex was tested by size test instrument. Some results are as follows:(1) Nano-SiO₂/PMMA composite is prepared through polymerizationreaction of MMA and nano-SiO₂ modified by stearinic acid as emulsifierof SDS. Solid content and percent conversion of the system is the mostwhen the concentration of SDS is 0.2ï¼…, or the use of initiator is 1-2ï¼…ofmonomer use, or alkalinity condition, or reactive time is 7 hours. As theconcentration of emulsifier and initiator increased, the latex diameterdecreased. While increased the concentration of monomer and thepolymeric time, the diameter of latex gradually increased. And thediameter is the most with 7h. PMMA did graft to the surface of SiO₂ byIR and TEM. SiO₂ in latex is stable, and the stability of the composite intoluene is significantly improved in comparison with that of unmodifiedSiO₂.(2) The result of nano-ZnO performed with oleic acid(OA) isoptimally when use level of OA is 5ï¼…of ZnO use. ZnO/PMMAcomposite was prepared through emulsion polymerization of MMA andnano-ZnO modified by OA as lacquer solvent of ethanol, emulsifier ofSDS and medium speed. Percent conversion of polymer is the maximumwhen the use of SDS is 0.1 g. As the concentration of emulsifier reduced and the concentration of initiator increased, percent conversion decreased.While increased the concentration of emulsifier and initiator, the diameterof latex gradually decreased. And while increased the use of monomer,the diameter of latex gradually increased. PMMA did graft to the surfaceof ZnO by IR and TEM. The polymerization did not alter crystalsstructure of ZnO. Particle size of the latex is 141.7nm and the distributionis narrow. The dispersion stability of the composite in toluene isimproved in comparison with that of unmodified ZnO.