Pickering Emulsion Polymerization of Styrene-co-butyl Acrylate Nanoparticles by Using Cloisite Na+ as Surfactant

Cloisite Na was used as a solid surfactant (stabilizer) in Pickering emulsion polymerization of styrene-co-butyl acrylate in presence of oil soluble initiator, azobisisobutyronitrile (AIBN) and water soluble initiator, potassium persulfate (KPS). Fourier transform infrared (FTIR) spectrum approved the corporation of Cloisite Na layers within the polymer matrix. Effect of clay content was assessed on the particle size and polymerization rate for both kinds of initiators. Reduction of particle size (nearly 100 nm) and enhancement of polymerization rate (30% and 10% for formulation with KPS and AIBN respectively) was observed by adding clay material to the blank recipe. Morphology of the particles was investigated by SEM and TEM. Formation of armored latex particles (covered particles with clay layers) with approximately 200 nm in diameter was proved via these micrographs. Furthermore, exfoliated structure of nanocomposites was revealed by XRD for sample containing water soluble initiator (ionic initiator) and oil soluble initiator. Impress of Cloisite Na structure on Tg of synthesized copolymer (soap free systems) was investigated by DSC as large changes was observed (approximately 10-15 °C). Effect of Tg on film formation of latexes was also evaluated.