Living anionic surface-initiated polymerization (LASIP) of styrene from clay nanoparticles using surface bound 1,1-diphenylethylene (DPE) initiators

Nanocomposite materials of clay nanoparticles and polystyrene were prepared using living anionic surface-initiated polymerization (LASIP). The montmorillonite clay surface and intergallery interfaces were intercalated with 1,1-diphenylethylene (DPE), an organic cation and initiator derivative for anionic polymerization. Its intercalation was confirmed by a series of characterization methods including X-ray diffraction (XRD), FT-IR spectroscopy, thermogravimetric analysis (TGA), and X-ray photoelectron spectroscopy (XPS). The results showed a complete replacement of the Na counterions by the charged initiators. LASIP was performed in a high-vacuum reaction setup for anionic polymerization using different styrene monomer/initiator ratios. A living anionic polymerization mechanism was determined from molecular weight (MW) data and the molecular weight distribution. A comparison of FT-IR, TGA, XPS, XRD, and atomic force microscopy (AFM) data confirmed that polystyrene was indeed "grafted from" clay surfaces for these composite materials. The initiation efficiency was distinguished between surface- and intergallery interface-bound initiators.