PVD-Grown photocatalytic TiO2 thin films on PVDF substrates for sensors and actuators applications
Titanium dioxide's self-cleaning effect has been broadly used in textiles, paints, windows, residual water treatment, amongst various other photocatalytic applications. Polymer substrates have found their way in the semiconductor industry as a base layer for flexible electronics, as well as in sensor and actuator applications. The optimum performance of these systems may be affected by dirt adsorbed on its surface, which can also originate mechanisms for the degradation of the polymer. These thin films have been deposited on electroactive poly(vinilidene fluoride) - PVDF - polymer substrates by unbalanced reactive magnetron sputtering. Rutherford Backscattering experiments evidenced that these coatings have a TiO2 stoichiometry. Raman spectroscopy experiments revealed that the as-deposited coatings on polymer substrates are mostly amorphous, however evidence of anatase and rutile nano-crystalline phases can be found. The photocatalytic behavior of the titanium dioxide coatings was determined by combined ultra-violet irradiation and absorption measurements of a particular dye in the presence of the catalyst. In order to assess the mechanical behavior of the as-sputtered films, the film/substrate composite system was loaded unidirectionally using a tensile testing machine. The stress-strain curves were analyzed and correlated with photocatalytic efficiency along these curves, as well as with the structural data.