Preparation Of TiO₂/SiO₂ Composite Nanoparticles And The Application On Anti-ultraviolet And Superhydrophobic Multifunctional Cotton Fabrics

With the development of science and technology, the research and development of multifunctional textiles has becoming popular. Nano TiO₂ has good ultraviolet absorption property, which can be applied on anti-ultraviolet radiation finishing of fabrics. However,it also has strong photocatalytic property, which can damage fiber fabrics treated by it,limiting its wide application. For nano composite materials, the core-shell structure composite materials have unique properties. The nano TiO₂/SiO₂ composite materials can be prepared by coating nano SiO₂ on the surface of nano TiO₂. The composite nanoparticles have ultraviolet absorption property, and the photocatalytic property of nano TiO₂ can be restrained. The anti-ultraviolet and superhydrophobic cotton fabrics can be obtained by the combination of nano composite materials and low surface energy materials.The multifunctional fabrics can be applied in life field like umbrellas, military and medical fields, which have extensive application perspective.In this paper, the TiO₂/SiO₂ composite nanoparticles were obtained by dispersing TiO₂ and guiding SiO₂ on the surface of Ti O₂ using polyvinylpyrrolidone（PVP）. The anti-ultraviolet and superhydrophobic multifunctional cotton fabrics were obtained by coating the Ti O₂/SiO₂ composite nanoparticles and modification of hexadecyltrimethoxysilane（HDTMS）. The specific contents are as follows:1. The preparation of TiO₂/SiO₂ composite nanoparticles. The TiO₂/SiO₂ composite nanoparticles（nano-TiO₂ was coated by SiO₂ based on nano-TiO₂ powder） were successfully prepared by using polyvinylpyrrolidone（PVP） as the dispersant and structural guiding agent, and tetraethyl orthosilicate（TEOS） as the precursor of SiO₂. The influence of PVP amount, the silicon and titanium ratio, the ammonium hydroxide amount and the reaction temperature on the properties of composite particles were discussed. The resultsshowed that when the PVP amount was 0.025%, the silicon and titanium ratio was 2:1, the ammonium hydroxide amount was 5mL, and the reaction temperature was 35℃, TiO₂ nanoparticles were coated well by SiO₂, and the cotton fabrics treated by TiO₂/SiO₂ composite nanoparticles and HDTMS had excellent anti-ultraviolet and superhydrophobic properties, and the superhydrophobic property of treated cotton fabrics had good stability under ultraviolet radiation.2. The characterization and primary application of Ti O₂/SiO₂ composite nanoparticles. The Fourier transform infrared spectroscopy（FT-IR） and the comparison of photocatalytic property showed that nano TiO₂ were coated with nano SiO₂. The X-ray diffraction（XRD） analysis showed that coating of nano SiO₂ on nano TiO₂ surface was not very dense, which could be good for the ultraviolet absorption of composite nanoparticles.The scanning electron microscope（SEM） of composite nanoparticles showed that Ti O₂ surface was covered with nano SiO₂, and the average diameter of composite nanoparticles was about 300 nm. When the cotton fabrics were treated by composite nanoparticles and HDTMS, the treated cotton fabrics had the ultraviolet protection factor（UPF） of 115.42, the UVA（320-420nm） transmittance of 3.35%, the water contact angle（WCA） of 156.54o and the water shedding angle（WSA） of 8o, showing excellent anti-ultraviolet and superhydrophobic properties. Besides, the treated cotton fabrics still had the WCA of 152.73o and the WSA of 9o after UV irradiation for 24 h, and had good stability under ultraviolet radiation.3. The investigation of anti-ultraviolet and superhydrophobic finishing process of cotton fabrics based on TiO₂/SiO₂ composite nanoparticles and the properties analysis of treated fabrics. The influence of nano TiO₂/SiO₂ composite particles amount, the concentration of HDTMS, curing temperature, and curing time on anti-ultraviolet and superhydrophobic properties of finishing fabrics were discussed. The best finishing process was obtained: TiO₂/SiO₂ composite nanoparticles amount was 0.6%, the concentration of HDTMS was 40g/L, the curing temperature was 160℃, and the curing time was 5min.From the SEM of fabrics, the surface of untreated cotton fabrics was relatively smooth, and the surface of treated fabrics had obvious roughness with composite nanoparticles. The cotton fabrics treated using the best finishing process had the WCA of 159.31o and the WSA of 7o, which still had the WCA of 155.24o and the WSA of 8o after UV irradiation for24 h,showing good stability under ultraviolet radiation. But the treated cotton fabrics had poor washing fastness. The breaking strength and gas permeability of treated fabrics hadbeen reduced slightly. On the whole, the treated cotton fabrics can meet the requirement of application.