Synthesis and Characterization of All Acrylic Block Copolymer/Clay Nanocomposites Prepared via Surface Initiated Atom Transfer Radical Polymerization (SI-ATRP)

Surface initiated polymerization (SIP) is an emerging powerful tool to modify and tailor the surface properties of nanoparticles. Among different methods of SIP, surface initiated atom transfer radical polymerization (SI-ATRP) has several strategic advantages over other methods of polymerizations. This investigation reports the preparation and characterization of poly(2-ethylhexyl acrylate) (PEHA)/clay nanocomposite from nanoclay surface via SI-ATRP and poly(2-ethylhexyl acrylate)-block-poly(methyl methacrylate) (PEHA-b-PMMA)/clay nanocomposite via conventional ATRP. To carry out SI-ATRP, the nanoclay (Cloisite Na+) surface was first modified by incorporating an ATRP initiator (2-bromopropionyl bromide) to nanoclay surface via a grafting reaction. The prepared bromo-functionalized nanoclay (Clay-Br) was then used to carry out SI-ATRP of 2-ethylhexyl acrylate (EHA) at 90 degrees C using CuBr as catalyst in combination with N, N, N', N '', N ''- pentamethyl diethylenetriamine (PMDETA) as the ligand. The macroinitiator (clay-PEHA-Br) was used to prepare PEHA-b-PMMA/clay nanocomposites via conventional ATRP using the same reaction conditions as SI-ATRP of EHA. A series of PEHA-b-PMMA/clay nanocomposites were prepared via ATRP. The prepared PEHA/clay nanocomposites and PEHA-b-PMMA/clay nanocomposites were characterized by WAXD and TEM analyses. DSC analysis of PEHA-b-PMMA/clay nanocomposites showed two T-g values corresponding to two blocks present in the block copolymers. TGA analysis was also carried out to study the thermal stability of PEHA/clay nanocomposites and PEHA-b-PMMA/clay nanocomposites at different nanoclay loading. The chemical structure and molecular weights of the prepared polymers were analyzed by Fourier transform infrared (FT-IR), H-1 NMR, and gel permeation chromatography (GPC) analyses.