Beneficial Effect of Nanoclay in Atom Transfer Radical Polymerization of Ethyl Acrylate:  A One Pot Preparation of Tailor-Made Polymer Nanocomposite

The atom transfer radical polymerization (ATRP) of ethyl acrylate (EA) was carried out in bulk at 90 °C in the presence of organically modified nanoclay as an additive. A remarkable enhancement in the rate of polymerization was observed and it was compared with the ATRP of EA without nanoclay. Time of dispersion of clay in monomer (t_d) prior to polymerization and the extent of clay loading were found to have a positive effect on polymerization rate. The polymerization proceeded through first-order kinetics and molecular weights increased linearly with conversion, close to the targeted molecular weights. The living nature of the end group was confirmed by MALDI-TOF-mass spectrometry and a chain extension experiment. Several factors may account for this unexpectedly rapid, yet controlled ATRP of EA in the presence of nanoclay additive. Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectrometry (NMR), and dynamic mechanical thermal analysis (DMTA) studies showed that the added nanoclay interacts with the carbonyl group (>CO) of the monomer and reduces the electron density in the conjugated CC bond, thereby increasing the reactivity of the monomer. This particular interaction also has an effect in the dynamic equilibrium of activation−deactivation cycle in ATRP. Interestingly, the resulting nanocomposites had exfoliated clay particles, as evident from wide-angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM) studies.