1D Organization of ZnO and TiO2 nanoparticles toward advanced photonic and photocatalytic materials

Nowadays Chemist are request to construct more and more complex architectures bearing multifunctionalities enable to respond to external stimuli. The construction of such complex architectures will be addressed through strong interplay in chemical science, as proposed recently with the concept of integrative Chemistry.[1] We synthesized PVA/ZnO-nanorods composite fibers using co-axial flux extrusion.[2] These fibers exhibit higher anisotropic photonic properties, both in absorption and emission, as a result of the collective alignment of the ZnO nanorods along the main axis of the PVA fiber. This photonic anisotropy is triggered by a synergistic interaction between the PVA matrix, stretched above Tg, and cooled down under strain. Compared with non-elongated fibers that present an isotropic emission, composite fibers previously submitted to a tensile stress absorb selectively UV emission when the polarized laser beam is parallel to the main axis of the fiber. In addition, their photolumincescence is also anisotropic, with a waveguide behavior along the main axis of the fiber. Mechanical properties of these composite fibers are also drastically improved, compared with pure PVA fibers: the longitudinal Young modulus of these fibers is increased from 2 to 6 GPa upon ZnO addition, a value similar to those already observed for composite fibers, prepared either with carbon nanotubes, or Vanadium Oxide macroscopic fibers.

[1] N. Brun, S. Ungureanu, H. Deleuze and R. Backov. Chem. Soc. Rev., 2011, 40, 771
[2] Kinadjian, N., Achard, M.-F., Julián-López, B., Maugey, M., Poulin, P., Prouzet, E. and Backov, R. (2012). Adv. Funct. Mater.. doi: 10.1002/adfm.201200360