Enhancement of styrene conversion in organic/inorganic hybrid materials by using malononitrile in controlled radical polymerization

A grafting from' method has been used to fabricate polystyrene/iron-based oxide materials. The styrene conversion is considerably low when initiator-modified iron-based oxides are used. We demonstrate that malononitrile in catalytic amounts strongly enhances the monomer conversion. The hybrid materials are fabricated using a two-step process. First, an atom transfer radical polymerization initiator molecule containing a phosphonic acid group (2-bromo-2-methylpropionic acid 11-phosphonoundecyl ester) is covalently immobilized onto the surface of CoFe2O4 and -Fe2O3 nanoparticles. In the second step, the polymerization of styrene is performed at the particle surface with and without the addition of malononitrile. Fourier transform infrared spectroscopy, transmission electron microscopy, thermogravimetry and size exclusion chromatography are used to characterize the metal oxide, the initiator molecule grafted onto the metal oxide, the hybrid material and the polymer chains.(c) 2013 Society of Chemical Industry