Synthesis and Characterization of Exfoliated Poly(styrene-co-methyl methacrylate) Nanocomposite via Miniemulsion Atom Transfer Radical Polymerization: An Activators Generated by Electron Transfer Approach

Exfoliated poly(styrene-co-methyl methacrylate) nanocomposites were synthesized using activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP). Miniemulsion polymerization was used for its abundant advantages to encapsulate inorganic materials and eliminate organic solvents from products for environmentally friendly purposes. Cetyltrimethylammonium bromide (CTAB) as a cationic surfactant, which is an effective surfactant at higher temperatures, was used to stabilize the miniemulsion system. Successful miniemulsion AGET ATRP was carried out by using 4,4'-dinonyl-2,2'-bipyridine (dNbPy) as a hydrophobic ligand. Formation of monodispersed droplets and particles with sizes in the range of 200 nm was examined by dynamic light scattering (DLS). Conversion and molecular weight study were also carried out using gravimetry and gel permeation chromatography, respectively. By adding clay content, a decrease in the conversion and molecular weight of the nanocomposites are observed. However, an increase in the PDI values of nanocomposites was observed by the addition of nanoclay content. Thermogravimetric analysis results demonstrate that thermal stability of all the nanocomposites in comparison with the neat copolymer increases. Differential scanning calorimetry results show that T-g decreases by increasing clay content. Monodisperse distribution of spherical shape particles with sizes in the range of similar to 200 nm was demonstrated by using scanning electron microscopy images of nanocomposite containing 1 wt% of nanoclay, which is more compiled with DLS results. Transmission electron microscopy results shows well-dispersed exfoliated clay layers in the polymer matrix of PSMNM 1, which is coincidence with X-ray diffraction data. POLYM. COMPOS., 32:1979-1987, 2011. (C) 2011 Society of Plastics Engineers