Synthesis and Characterization of Clay Dispersed Polystyrene Nanocomposite via Atom Transfer Radical Polymerization

Finely well-defined polystyrene nanocomposites were prepared by ATRP method in bulk at 110 degrees C using organically modified montemorillonite, cloisite 30B. The living nature of ATRP reaction was employed to in situ synthesize tailor-made polystyrene nanocomposite with narrow molecular weight distribution and controlled molecular weight polystyrene chains. The amount of clay loading and time of swelling of clay in the monomer before polymerization were proved to have a positive effect on polymerization rate and also broadened the molecular weight destribution. The gas chromatography (GC) results showed the linear increase of Ln(M-o/M) versus time, which indicates the controlled/living polymerization in the presence of nanoclay. Another confirmation of the living nature of the polymerization was linear elevation of molecular weight against monomer conversion concluded from gel permeation chromatography (GPC) data. X-ray diffraction analysis showed the interlayer spacing of nanoclay platelets as well as the exfoliated clay morphology in the nanocomposite samples. Transfer electron microscopy (TEM) revealed the exfoliated morphology of the in situ prepared nanocomposite as opposed to conventional solution-blending technique which resulted in an intercalated structure. The effect of nanoclay on acceleration of polymerization was proved by GC and GPC; similarly, Fourier transform infrared spectroscopy (FTIR) was used to discuss the reasons of such a rate acceleration. A shifting in the wave number of characteristic bonds of nanoclay after polymerization mostly in the case of O-H and Si-O bonds, revealed the interaction between polymer chains and clay layers which resulted in an accelerated polymerization process. The living nature of polymeric chains was more elucidated by FTIR data. Atomic force microscopy (AFM) images also confirmed the proper dispersion of nanoparticles in the polymer medium. POLYM. COMPOS., 31:1829-1837, 2010. (C) 2010 Society of Plastics Engineers