ZnO/PVA Macroscopic Fibers Bearing Anisotropic Photonic Properties

摘要

Composite PVA/ZnO-nanorods fibers, synthesized through co-axial flux extrusion 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 the glass transition temperature (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 V_2O_5 macroscopic fibers.