Preparation Of Organic-inorganic Nanocomposites Via Inverse Microemulsion Polymerization In Situ

Because organic-inorganic nanocomposites can show good properties of organic and inorganic components, they absorb more and more attention. It is difficult to get true nanocomposites due to the aggregation of nanoparticles during mixing. The aim of this paper is trying to synthesize nanocomposites via inverse microemulsion polymerization in situ.(1) Transparent emulsifier systems were prepared by using SDS, Ammonium Methyl Ricinoleic Acid Sulfate and SE-10N as surfactant, among Which the Ammonium Methyl Ricinoleic Acid Sulfate and SE-10N were reactive surfactants.(2) The pseudo-ternary phase diagrams of MMA/AA/SDS-H2O, Ammonium Methyl Ricinoleic Acid Sulfate/MMA/H₂O and SE-10N/MMA-AA/H₂O were figured out. The structure types of these microemulsions were characterized by the shapes of conductivity curves. Tests showed that the three systems all had obvious inverse microemulsion area.(3) Microemulsion polymerization was carried out by using thermal initiation, redox initiation and photo initiation respectively. Tests showed that photo initiation at low temperature is a better way for microemulsion polymerization.(4) There was white solid precipitated while adding respectively electrolyte aqueous solution including Ba²+, Cd²+, Zn²+, Pb²+ or Ag⁺ to the MMA/AA/SDS-H₂O inverse microemulsion system, and no inverse microemulsion system including the above cations was prepared.(5) Adding of electrolyte aqueous solution to the Ammonium Methyl Ricinoleic Acid Sulfate/MMA/H₂O system could make the solubilization capacity decreased obviously, and with the increase of the concentration of the electrolyte solution, the solubilization capacity decreased further. Opaque composites containing BaSO₄ particles were obtained after polymerization of Ammonium Methyl Ricinoleic Acid Sulfate /MMA/H₂O system.(6) There was precipitation separated in the process of preparing inorganic particles in the SE-10N/MMA-AA/H₂O system. When no cosurfactant AA existed in the system, no precipitation separated. This showed that the adding of AA to thesystem could decrease obviously the intension of interfacial film, so the system including AA was ineffective to prepare inorganic nanoparticles.(7) When the microemulsion system built by SE-10N didn't include the cosurfactant AA, the polymerization product was opaque, which became transparent while adding right amount cross linking agent TMPTA. This showed that the adding of cross linking agent could inhibit obviously the phase separation in the polymerization process.(8) After the formation of nanoparticles, microemulsion containing TMPTA was initiated to prepare transparent nanocomposites. Because the composite material can not be cut into thin slices by means of ultra microtome, microstructure of composites can not be investigated by TEM.