Poly(styrene-co-butyl acrylate)/Clay Nanocomposite Latexes Synthesized via In Situ Atom Transfer Radical Polymerization in Miniemulsion: Activators Generated by Electron Transfer Approach

Water born poly(styrene-butyl acrylate)/clay nanocomposite latexes were synthesized by a novel initiating system of activators generated by electron transfer (AGET) in a system of atom transfer radical polymerization (ATRP). Initially, the clay was swelled in a mixture of styrene, butyl acrylate, and hexadecane. The mixture was then sonicated to obtain a stable miniemulsion. To synthesize poly(styrene-butyl acrylate)/clay nanocomposite latexes, the reducing agent (ascorbic acid) was added dropwise to the reactor (to reduce termination reactions). Particle size and particle size distribution of resulting nanocomposite latexes were determined by dynamic light scattering (DLS). These latex particles were produced with diameters in the size range of 138-171 nm. In addition, the increase in clay content led to increased particles size. Number and weight-average molecular weights of the resultant copolymer nanocomposites and their molecular weight distributions were determined by gel permeation chromatography. The narrow molecularweight distribution of the nanocomposites is an indication of a successful ATRP which was accomplished in miniemulsion formation. Using 1H NMR, copolymers were characterized and the mol ratios of monomers in copolymer composition were calculated. X-Ray diffraction and transmission electron microscopy results showed the mixed intercalated and exfoliated morphologies of nanocomposites in which homogeneous distributions of clay layers in the polymer matrix have been achieved.