Organic-skinned inorganic nanoparticles: surface-confined polymerization of 6-(3-thienyl) hexanoic acid bound to nanocrystalline TiO 2

Abstract

There are many practical difficulties in direct adsorption of polymers onto nanocrystalline inorganic oxide surface such as Al 2O 3 and TiO 2 mainly due to the insolubility of polymers in solvents or polymer agglomeration during adsorption process. As an alternative approach to the direct polymer adsorption, we propose surface-bound polymerization of pre-adsorbed monomers. 6-(3-Thienyl)hexanoic acid (THA) was used as a monomer for poly[3-(5- carboxypentyl)thiophene-2,5-diyl] (PTHA). PTHA-coated nanocrystalline TiO 2/FTO glass electrodes were prepared by immersing THA-adsorbed electrodes in FeCl 3 oxidant solution. Characterization by ultraviolet/visible/infrared spectroscopy and thermal analysis showed that the monolayer of regiorandom-structured PTHA was successfully formed from intermolecular bonding between neighbored THA surface-bound to TiO 2. The anchoring functional groups (-COOH) of the surface-crawling PTHA were completely utilized for strong bonding to the surface of TiO 2. © 2011 Saji et al.