Synthesis of well-defined clay encapsulated poly(styreneco-butyl acrylate) nanocomposite latexes via reverse atom transfer radical polymerization in miniemulsion

Well-defined poly(styrene-co-butyl acrylate) nanocomposite latexes were synthesized via reverse atom transfer radical polymerization (RATRP) in miniemulsion. Successful RATRP was carried out by using a hydrophobic ligand of 4,4'-dinonyl-2,2'-bipyridine (dNbpy) and a cationic surfactant of cetyltrimethylammonium bromide (CTAB). Dynamic light scattering (DLS) results show that droplets and particles with sizes in the range of about 170 nm were formed. Overall, conversion and molecular weight evaluation were performed by using gravimetry and size exclusion chromatography (SEC), respectively. Increasing nanoclay loading resulted in an increase in the conversion and molecular weight of the nanocomposites. However, polydispersity index (PDI) values increased by adding nanoclay content. Thermal stability of all the nanocomposites improved in comparison with the neat copolymer, according to the thermogravimetric analysis (TGA) results. Differential scanning calorimetry (DSC) results showed that the glass transition temperature (T g) increased by increasing nanoclay content. Scanning electron microscopy (SEM) images of the nanocomposite with 1 wt% of nanoclay showed a monodisperse distribution of spherical particles, with sizes in the range of approximately 170 nm, as confirmed by the DLS data. Similarly, transmission electron microscopy (TEM) images show that clay layers are delaminated and well dispersed in the matrix of nanocomposite with 1 wt% clay content.