| Titanium dioxide (TiO2) nanoparticles possess the unique photocatalitic, opto-electrical, bactericidal and ultra-violet (UV) absorption properties, which common TiO2 materials don't have, due to quantum effect, surface effect and quantum tunneling effect. It has a variety of potential applications in environmental, biomedicine, electronic, construction, packing, and other industries. In this research, low temperature magnetron sputter coating was employed to deposit nanostructured TiO2 films on the surface of nonwovens and polymer fibers to functionalize the textile materials. The use of magnetron sputter coating not only overcame the problems of nanoparticle aggregation as filling particles, but also shortened the production processes and eliminated the water pollution. The use of magnetron sputter coating, on the other hand, could cut the processing cost. This research explored the formation principle, preparation techniques, properties and reliability of the nanostructured TiO2 deposited on the surface of textile substrates to meet the demands of the markets for functional textiles.The functional TiO2 films were deposited on polyester (PET) nonwovens in this project. Atomic force microscopy (AFM), X-ray diffraction (XRD), X-ray energy dispensive spectrometer (EDX) and X-ray photoelectron spectroscopy (XPS) were employed to study the topography, structure and chemical compositions of coated films, respectively. The growth mechanism on the nonwoven surface and the effects of main sputtering parameters on physicochemical structure of TiO2 films and its photocatalytic degradation activity of methylene blue(MB) aqueous solutions were investigated. The antibacterial and antistatic properties, optical transmission, photo-induced hydrophilicity and photocatalytic degradation formaldehyde of nonwovens coated with TiO2 films were also tested, respectively. At the same time, in order to assess the reliability of the as-sputtered films, the failure process of TiO2 films coated on polypropylene(PP) fibers was explored using the uniaxial tensile test and the in-suit observation in the scanning electron microscope (SEM). The shear-lag model was used to analysis distribution and transmission of tensile stress in the PP fiber, coating/substrate interface and TiO2 films. The strength distributions of TiO2 coated PP fibers deposited at different sputtering parameters were analyzed using Weibull statistical theory. The reliability of composite functional materials was further evaluated. The methods used to improve the adhesion between the TiO2 films and fiber substrates, and the reliability of TiO2 coated composite materials was discussed.The test results indicated that the compositions, structures, surface topography and deposition rate of TiO2 films were evidently affected by the main sputtering parameters, which also had major effect on the photocatalysis activity of TiO2 films. The increase of sputtering power led to the increase in continuum and compactness of TiO2 films and the transition of the crystalline structure of TiO2 films from amorphous phase to anatase crystalline structure. The photocatalytic degradability of PET nonwoven fabric deposited with TiO2 films on MB was enhanced by increase of the sputtering power within a proper range. Lower sputtering pressure was, more even and compact TiO2 films could be prepared on PET nonwoven fabric. But the photocatalytic degradability of PET nonwoven fabric with TiO2 films prepared at a certain sputtering time process on MB was slight affected by sputtering work pressure. It was easily to synthesize stoichiometric TiO2 films with the increasing of oxygen flow in the sputtering process. The photocatalysis activity improved because of the decrease in the oxygen vacancies of TiO2 films. With the same sputtering time, if oxygen flow was too high in the process, the photocatalysis activity decreased due to the decease in deposition rate and thickness of TiO2 films. The growth model of nanostructured TiO2 films formed on PET and PP substrates could be considered as nucleus growth as a whole. The photocatalytic degradability on MB increased as the thickness of TiO2 films increased, while this trend was not very evident when the thickness of TiO2 films reached a certain degree. In addition, TiO2 coated PET nonwoven fabric prepared under confirmed processing condition showed excellent functional properties of antibacterial, anti-ultraviolet radiation, antistatic, photo-induced hydrophilicity and photocatalytic degradation for formaldehyde.The uniaxial tensile tests proved that the reliability of TiO2 coated nonwovens is controlled by the quality of the coating, and especially by its adhesion to the fiber substrate, both being influenced by the process-induced internal stress. So the first method to improve the reliability of TiO2 coating is to control sputtering parameters reasonably, in order to optimize the nanostructure of TiO2 films and reduce the influence of internal stress and interfacial adhesion strength between TiO2 films and fiber substrate. The other effective methods are to use plasma pretreatment to improve the growing condition of TiO2 nanoparticles and reasonably controlling transition interphase layer which changes gradually from Ti metal, Ti suboxide to stoichiometric TiO2 films to reduce film internal stress and improve interfacial adhesion strength.
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