Polyacrylonitrile/electroconductive TiO<Subscript>2</Subscript> nanoparticles composite fibers <Emphasis Type="Italic">via</Emphasis> wet-spinning

For the first time, novel polyacrylonitrile (PAN)/electroconductive TiO₂ (EC-TiO₂) nanoparticles composite fibers have been successfully spun via wet-spinning. The composite fibers had uniform diameter and homogeneous surface. Moreover, at low content of EC-TiO₂ nanoparticles, the composite fibers realized a transition from an insulator to a conductor. This work has provided a simple and effective avenue for the production of PAN/EC-TiO₂ nanoparticles composite fibers that have great potential applications in the antistatic textiles.     

Effect of UV irradiation on cellulase degradation of cellulose acetate containing TiO<Subscript>2</Subscript>

Cellulose acetate (CA) films containing anatase type titanium dioxide (TiO₂) nanoparticles were prepared by solution casting. The film surface was modified by UV irradiation using a grid type UV irradiator. The UV irradiation caused slight increase in photodegradation of the CA films with TiO₂ compared to the CA film alone. However, CA films irrespective of TiO₂ content did not show a significant enzymatic degradation by a cellulase fromAspergillus niger without UV irradiation. Upon UV irradiation, the biodegradability remarkably improved even in the CA film without TiO₂. The irradiation of CA films decreased both the water contact angle and the degree of substitution (DS) implying the decrease in acetyl groups of the CA film surface due to the photo-scission of the acetyl group and photooxidation, resulting in more facile biodegradation of the surface film layer. The substantial enhancement in biodegradation of the UV irradiated CA film containing TiO₂ was attributed to the increased hydrophilicity, lowered DS and zeta potential due to the photoscission and the photooxidation effect of UV light. Also the increased surface area of the CA film due to the photocatalysis of TiO₂ particles may encourage the facile biodegradation.     

Multifunctional modification of wool fabric using graphene/TiO<Subscript>2</Subscript> nanocomposite

In this study, a new finishing technique is introduced through treatment of wool fabric with graphene/TiO₂ nanocomposite. Graphene oxide/titanium dioxide nanocomposite first applied on the wool fabric by hydrolysis of titanium isopropoxide in graphene oxide suspension and then this coating chemically converted by sodium hydrosulfite to graphene/TiO₂ nanocomposite. The homogenous distribution of the graphene/TiO₂ nanocomposite on the fiber surface was confirmed by field emission scanning electron microscopy (FE-SEM), Energy-dispersive X-ray spectroscopy (EDS) and X-ray mapping. X-ray diffraction patterns proved the presence of titanium dioxide nanoparticles with a crystal size of 127 Å on the treated wool fabric. Also, the defect analysis based on X-ray photoelectron spectroscopy (XPS) established the composition of the nanocomposite. Other characteristics of treated fabrics such as antibacterial activity, photo-catalytic self-cleaning, electrical resistivity, ultraviolet (UV) blocking activity and cytotoxicity were also assessed. The treated wool fabrics possess significant antibacterial activity and photo-catalytic self-cleaning property by degradation of methylene blue under sunlight irradiation. Moreover, this process has no negative effect on cytotoxicity of the treated fabric even reduces electrical resistivity and improves UV blocking activity.     

A Novel Green Stabilization of TiO<Subscript>2</Subscript> Nanoparticles onto Cotton

Facile embedding of TiO₂ nanoparticles onto cotton fabric has been successfully attained by ultraviolet light irradiations. The adhesion of nanoparticles with fibre surface, tensile behaviour and physicochemical changes before and after ultraviolet treatment were investigated by scanning electron microscopy, energy dispersive X-ray and inductive couple plasma-atomic emission spectroscopy. Experimental variables i.e. dosage of TiO₂ nanoparticles, temperature of the system and time of ultraviolet irradiations were optimised by central composite design and response surface methodology. Moreover, two different mathematical models were developed for incorporated TiO₂ onto cotton and tensile strength of cotton after ultraviolet treatment and used further to testify the obtained results. Self-clean fabric through a synergistic combination of cotton with highly photo active TiO₂ nanoparticles was produced. Stability against ultraviolet irradiations and self-cleaning properties of the produced fabric were evaluated.     

Coloration and Decoloration of Textiles Using a TiO<Subscript>2</Subscript> Composite Pigment

A colorable pigment was prepared by dye adsorption onto titanium dioxide and subsequent silane coating. The effects of pH value, dye concentration, and adsorption times on dye adsorption were discussed. Large adsorption capacity of an anionic dye was obtained at pH value of 2 and the adsorption process was well described by the Langmuir isotherm model. Good dyeability and color fastness of pigment dyed fabric were achieved in the normal life cycle under sunlight. The decoloration of pigment was realized through photocatalytic degradation of dye molecules by titanium dioxide under ultraviolet irradiation when reusing the pigment dyed textiles after disposal. The new absorption peaks in the FTIR spectrum at 2924.95 cm^-1, 1714.91 cm^-1, 1461.17 cm^-1, and 1289 cm^-1 verified silane modification. Silane modification improved fixation of dyes onto the pigment and immobilization of pigments onto substrates. The close attachment of silane coating layer to titanium dioxide was conducive to photodegradation of dye molecules in the pigment.     

Spherical Bacterial Cellulose/TiO<Subscript>2</Subscript> Nanocomposite with Potential Application in Contaminants Removal from Wastewater by Photocatalysis

Contaminants are often found in aquatic environments, for instance, heavy metals, dyes, parasites, pesticides, hormones and pharmaceuticals. Therefore, large amounts of these contaminants reaches wastewater via industrial and domestic effluents, causing major concern to human health. Heterogeneous photocatalysis is a technique for removing these contaminants in order to achieve better efficiency in water treatment. Then, bacterial cellulose (BC) produced in an agitated culture can form spherical bodies composed of nanofibers with high specific surface area. Moreover, Titanium dioxide (TiO₂) is a semiconductor containing high photocatalytic activity capacity. Thus, the main objective in this work was to produce spherical BC/TiO₂ nanocomposites for contaminants removal from wastewater by photocatalysis process. The incorporation of TiO₂ nanoparticles in the spherical BC matrix was performed by ex situ and in situ methods. In addition, Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Analysis (TGA) were used as tools of morphological, chemical and thermal characterizations of the nanocomposites. Besides, photocatalysis tests were performed in order to evaluate the removal efficiency of methylene blue from aqueous solutions. The results of these tests exhibited a percentage of methylene blue removal of 70.83 and 89.58 % after 35 minutes for spherical BC/TiO₂ nanocomposites both, in situ and ex situ, respectively. Therefore, these results demonstrated that BC/TiO₂ to be a low cost material with high capacity of contaminants removing and a great potential for industrial applications.     

Experimental study on dyeing technical PET yarns having different TiO<Subscript>2</Subscript> contents

TiO₂ contents in yarns can influence color yield so that dyeing quality of industrial poly ethylene terephthalate (PET) yarns can be improved through the adjustment of TiO₂ contents. To evaluate the dyeing performance of color yield, the chips which included the different TiO₂ contents of 330, 550, and 1,100 ppm respectively were used to produce the yarns of different TiO₂ content by a spin-draft machine. The physical and structural properties of the yarns were measured to investigate effect of the TiO₂ contents on them. Dye uptake and dyeing rate were also evaluated using a colorimeter to compare the yarns having different TiO₂ contents. The experimental results showed that there were no appreciable variation in physical and structural properties among the yarn samples and no difference were observed among the dyed fabric samples with regard to dyeing uptake and dyeing rate. However, the color yield of dyed fabrics increased as TiO₂ contents decreased in the yarns especially when the fabric samples were dyed to pale shade. The physical reasoning could be proposed on why the yarns having low TiO₂ contents appeared to have higher color yield after dyeing.     

Synthesis of Ag-Loaded TiO<Subscript>2</Subscript> Electrospun Nanofibers for Photocatalytic Decolorization of Methylene Blue

Titanium dioxide (TiO₂) is one of the excellent photocatalysts used for degradation of environmetal pollutants. In this work, 2.5, 5.0 and 7.5 wt.% of silver (Ag)-loaded TiO₂ nanofibers of mean size 52–134 nm were synthesized by electrospinning method. These electrospun nanofibers were calcined at 500 °C to enable the transformation of Rutile (R) phase to Anatase (A), elimination of reaction moieties from the TiO₂ matrix and subsequently formation of Ag clusters. The effect of Ag loading on the morphology, crystal structure, phase transformation, and band gap of these electrospun nanofibers have been characterized by scannining electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), raman spectroscopy and UV-visible spectroscopy. These nanofibers exhibited a red-shift in the absorbance edge and a significant enhancement of light absorption in the wavelength range of 250–550 nm. These electrospun nanofibers were investigated for photodecomposition of methylene blue (MB), and photocatalytic decolorization rates were determined by pseudo-first-order equation. The rate constants for the pure and those of 2.5, 5.0, and 7.5 wt% Agloaded TiO₂ nanofibers were computed to be 0.1439 min^-1, 0.1608 min^-1, 0.1876 min^-1, and 0.2251 min^-1 respectively.     

Ladder-Structured Polysilsesquioxane/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> Nanocomposites for Transparent Wear-Resistant Windows

As a protective layer for deformable displays, we synthesized ladder-type polysilsesquioxanes (LPSQs) containing cyclic epoxy as a curable unit. The mechanical properties after photo- and thermal-curing of LPSQs with a small amount of added Al₂O₃ nanoparticles were compared with those of the pure LPSQs. The prepared LPSQ-Al₂O₃ nanocomposites and the pure LPSQs exhibited comparable optical transparencies and thermal stabilities. In addition, the degree of conversion of the applied epoxy units in LPSQs and the resulting mechanical properties, as monitored by Fourier transform infrared spectroscopy and nanoindentation tests, indicated that the addition of nanoparticles to LPSQs moderately enhanced the epoxy conversion rate and remarkably improved the wear resistance, including hardness, after photo-/thermal-curing processes. The LPSQ-Al₂O₃ nanocomposites achieved higher wear resistance than epoxy-silica nanocomposites containing similar curable functional groups and reinforcing fillers (silica). The excellent mechanical properties of the LPSQ-Al₂O₃ nanocomposites could be attributed to three-dimensionally interconnected networks of organic-inorganic hybrid-type chemical structures in the LPSQ as well as additional reinforcement from amine-functionalized Al₂O₃ nanoparticles covalently interconnected with the LPSQ. We believe that the devised LPSQ-Al₂O₃ nanocomposites could serve effectively as a wear-resistant platform for deformable display windows.     

In situ loading TiO<Subscript>2</Subscript> and its photocatalysis and UV resistance on cotton fabric

Anatase TiO₂ nanoparticles was in-situ formed on the cotton fabric by using tetrabutyl titanate (TBT) as a precursor through the normal pressure hydrothermal method. X-ray diffraction (XRD), Scanning electron microscopy (SEM), UV visible spectra (UV-VIS), ATR-IR were used as the characterization techniques. Photocatalytic performance of TiO₂ on the fabric surface was evaluated by methylene blue (MB), 4 kinds of the common living stains and three dyes under ultraviolet and visible light radiation. XRD analysis found that the TiO₂ loaded on the fabric was mainly anatase crystalline phase with particle size of 6.4 nm. SEM observed that a large number of nano TiO₂ particles are distributed on the fabric surface. UV-VIS test indicated that theTiO₂-coated fabric possessed an obvious absorption for ultraviolet. ATR-IR analysis indicated that the nano-TiO₂ possesses a strong affinity with the hydroxyl group of the cotton fabric, and the soaping tests showed that the TiO₂ was firmly bonded with the fabrics. The treated fabrics have good degradation ability for MB aqueous solution, and could degrade azo, anthraquinone and phthalocyanine dyes. The order of degradation of the common life stains was: pepper oil> tea > coffee > soy sauce.     

Preparation and UV-protective property of PVAc/ZnO and PVAc/TiO<Subscript>2</Subscript> microcapsules/poly(lactic acid) nanocomposites

The poly(vinyl acetate) (PVAc)/zinc oxide (ZnO) microcapsule and PVAc/titanium dioxide (TiO₂) microcapsule were synthesized via in-situ emulsion polymerization method. The PVAc/ZnO microcapsule and PVAc/TiO₂ microcapsule were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis(TG), transmission electron microscopy (TEM), and UV-visible spectroscopy (UV-vis). Effect of PVAc/ZnO microcapsule and PVAc/TiO₂ microcapsule on properties of poly(lactic acid) (PLA) was evaluated by UV-vis, SEM and mechanical properties test. The results showed that the addition of PVAc/ZnO and PVAc/TiO₂ microcapsules as a UV-blocking additive could significantly enhance UV-blocking property of PLA/PVAc/ZnO microcapsule composites and PLA/PVAc/TiO₂ microcapsule composites compared with pure PLA, PLA/ZnO composites and PLA/TiO₂ composites. The mechanical properties of PLA/PVAc/ZnO microcapsule composites were better than those of PLA/ZnO composites due to good dispersability and compatibility of PVAc/ZnO microcapsule in PLA matrix. Also, the mechanical properties of PLA/PVAc/TiO₂ microcapsule composites were better than those of pure PLA and PLA/TiO₂ composites. This study demonstrates the great potentials of the intrinsically UV shield additive PVAc/ZnO and PVAc/TiO₂ microcapsules in the application of high performance matrix resin and composite material.     

Development of UV Protective,Superhydrophobic and Antibacterial Textiles Using ZnO and TiO<Subscript>2</Subscript> Nanoparticles

In this research work, multifunctional cotton fabric comprising of UV protection, superhydrophobicity and antibacterial activity has been developed using facile pad-dry-cure method. In the first step, the concentration of repellent chemical has been optimized. Then, formulations containing nanoparticles of ZnO or TiO₂ along with optimized concentration of repellent chemical and organic-inorganic binder have been applied to cotton fabric followed by the evaluation of functional properties. The surface morphology and elemental composition of treated fabric has been characterized through SEM and EDX, respectively. The treated samples have shown promising UV protection, superhydrophobicity and antibacterial properties durable upto 20 washing cycles.     

Fabric objective measurement of the plasma-treated cotton fabric subjected to wrinkle-resistant finishing with BTCA and TiO<Subscript>2</Subscript> system

Handle is an important factor when designing the end-uses of fabric as it is also a critical factor for purchasing decision. In the present study, the Kawabata Evaluation System for Fabrics (KES-F) was used for measuring the fabric handle of BTCA-TiO₂ treated cotton fabric with or without plasma pre-treatment. The results revealed that the BTCA-TiO₂ treated cotton fabrics without plasma pre-treatment had a negative effect on tensile, shearing, compressional, and surface properties while the bending properties were improved. On the other hand, the plasma pre-treatment improved the tensile and compressional properties, but not the bending, shearing, and surface properties.     

Hard Surface-adhesive Properties of TiO<Subscript>2</Subscript> Nanoparticles-encapsulated Microparticles Prepared by Spray Drying and Surface Coating Method

The aim of this study is to compare hard surface-adhesive properties of TiO₂ nanoparticles (TNPs)-encapsulated microparticles prepared by spray drying and surface coating method. Thus, TNPs were encapsulated with chitosan by spray drying and poly(L-lysine) by surface coating method, which were selected as positively charged materials. And then, the TNPs-encapsulated microparticles were investigated by particle surface properties and adhesion properties on hydroxyapatite (HAP) surface as model for hard surface-adhesion. The characteristics of TNPs-encapsulated Chitosan microcapsules (CM) and TiO₂ nanoparticles coated with cationic poly(L-lysine) polymer (TNPs-PLL) were determined with scanning electron microscope (SEM) image and zeta-potentials. The hard surface-adhesive properties on HAP surface were confirmed with SEM and whitening test. The zeta-potentials of TNPs and HAP were negative, -13 mV and -18 mV respectively, while TNPsencapsulated CM, and TNPs-PLL of positively charged polymers were positive, 13 mV and 57 mV respectively. Whitening test was carried out on model surface when shaking the samples. TNPs-PLL were adhered to HAP surface very much more than those of TNPs-encapsulated CM. Also, the change value of whiteness of the HAP surface treated with TNPs-PLL is large evidently, compared with TNPs-encapsulated CM.     

Rapid fabrication and optimization of silk fibers supported and stabilized MnO<Subscript>2</Subscript> catalysts

We report on the in situ synthesis and stabilization of manganese dioxide (MnO₂) onto four different silk yarns (mulberry, tasar, muga and eri silks). A new ultrasound-assisted procedure was used to reduce permanganate (MnO₄ ^?) and yielded MnO₂ nanoparticles (NPs) on/in the different silk fibers. Using a factorial design we assessed the influence of the silk type, manganese precursor concentration, sonication time, and temperature. The results indicated no measurable effect of the process parameters on the silk structures, but significant correlation with the rate of degradation of methylene blue (MB) and the fraction of permanganate consumed. Further optimization of the factorial model identified the optimal process conditions for each silks: mulberry (150 min sonication, 20 mM permanganate), eri (360 min, 10 mM), tasar (150 min, 10 mM) and Muga (20 min, 10 mM). The operational stability (successive catalysis) of the optimum hybrids showed good performance over 5 cycles and most importantly reduced direct dye absorption relatively to dye oxidation. Overall, we found that all silks could template the formation and stabilization of different MnO₂ polymorphs and yielded catalytic instead of stoichiometric hybrid fibers.     

Self-cleaning Properties of Nylon 6 Fabrics Treated with Corona and TiO<Subscript>2</Subscript> Nanoparticles under Both Ultraviolet and Daylight Irradiations

Nylon 6 fabric with self-cleaning properties was prepared by corona discharge pre-treatment and coating with TiO₂ nanoparticles (NPs) using pad-dry-cure technique. The self-cleaning property was studied by discoloration of methylene blue (MB), ketchup, tea and coffee stains from the corona+TiO₂ treated nylon-6 fabric. Color difference (ΔΕ*), reflectance (R) and K/S of MB stain were investigated by diffuse reflectance spectrophotometry. The MB stain was almost completely removed from the corona+TiO₂ treated nylon surface after 24 h under UV light/daylight irradiation. Both of these phenomena (corona and TiO₂) led to an increase in the discoloration of stains under UV and daylight irradiations. The EDS analysis showed an increase in the concentration of deposited TiO₂ NPs coating after corona treatment. The FE-SEM images revealed that the surface of nylon 6 was coarser after the corona treatment. Also, the FE-SEM micrographs exhibited that a uniform layer of TiO₂ NPs was formed on the corona treated nylon fabric. The corona+TiO₂ treated nylon illustrated antibacterial activity against E. coli and B. subtillis microorganisms. The EDS and FE-SEM analysis confirmed that after 5 washing cycles, the amount of TiO₂ NPs was higher on the surface of corona+TiO₂ treated nylon than that of the fabric only treated with TiO₂ without corona pretreatment. This result justifies that the corona+TiO₂ treated nylon fabric with appropriate self-cleaning property can be applied cost-effectively in the textile industry.     

Ternary carboxymethyl chitosan-hemicellulose-nanosized TiO<Subscript>2</Subscript> composite as effective adsorbent for removal of heavy metal contaminants from water

A ternary composite consisting of carboxymethyl chitosan, hemicellulose, and nanosized TiO₂ (CHNT) was prepared by incorporating TiO₂ nanoparticles into the pre-synthesized carboxymethyl chitosan-hemicellulose polysaccharide network. The microstructure and chemical composition of the obtained CHNT was characterized by TEM, SEM, FTIR, and TGA. The adsorption of some toxic heavy metals including Ni(II), Cd(II), Cu(II), Hg(II), Mn(VII), and Cr(VI), onto the as-prepared CHNT composite was investigated. The effects of pH, temperature and contacting time on the adsorption process were studied. Results revealed that the CHNT composite exhibited efficient adsorption capacity of the above metal ions from aqueous solution due to its favorable chelating groups in structure. The adsorption process was best described by the pseudo-second-order kinetic model, while isotherm modeling revealed that the Langmuir equation better described the adsorption on CHNT as compared to Freundlich model. Moreover, the CHNT loaded metal ions can be easily regenerated with EDTA and reused repeatedly up to five cycles. The environmental friendly hybrids were expected to be a promising candidate for future practical application in heavy metal contaminated water treatment.     

Effect of phase transformation on physical and biological properties of PVA/CaFe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocomposite

The thermal treatment method was employed to achieve higher homogeneity of calcium ferrite (CaFe2O4) and Poly (vinyl alcohol) (PVA) nanocomposites. The influences of phase transformation on physical and biological properties of calcined specimens were investigated by various experimental techniques including X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), high resolution Field emission scanning electron microscope (FESEM) and Fourier transform infrared spectroscopy (FT-IR). Heat treatment was conducted at temperatures between 723 and 923 K, so that a phase transformation occurred from cubic to orthorhombic spinel structure at 923 K. The chemical analysis of the PVA/CaFe₂O₄ nanocomposite was performed by energy dispersion X-ray analysis (EDXA), demonstrated the PVA/CaFe₂O₄ nanocomposites contained the elements of C, Ca, Fe, and O. The formed nanocomposites exhibited ferromagnetic behaviors which were confirmed by using a vibrating sample magnetometer (VSM). The calcined specimens were carried out to an antimicrobial or antifungal test.     

Fabrication and characterization of nano Al<Subscript>2</Subscript>O<Subscript>3</Subscript> filled PVA:NH<Subscript>4</Subscript>SCN electrolyte nanofibers by electrospinning

Present paper reports a method of preparing polymer composite electrolyte nanofiber mat using polyvinyl alcohol (PVA), ammonium thiocynate (NH₄SCN) salt, and aluminium oxide (Al₂O₃) nano particles based on electrospinning technique. Two-stage process of preparation of nanofibers, namely, preparation of nano particles filled PVA electrolyte gel solution followed by its electrospinning has been used. The so obtained nanofibers have been characterized by XRD, DSC, SEM, and Conductivity measurements. XRD patterns affirm the formation of nanocomposite while SEM pictures reveal formation of fibers on a nano scale format (300–800 nm). Fibers of the electrolytes are seen to be thermally stable. Ionic conductivity of electrolyte fiber is seen to improve in the presence of nano filler at room temperature with a maximum at 5.31×10⁻³ Scm⁻¹ for 4 wt% filler concentration, which is comparable to that for corresponding dried gel electrolyte films.     

Electrospun in-situ hybrid polyurethane/nano-TiO<Subscript>2</Subscript> as wound dressings

By combining the organic-inorganic hybridization, wet phase inversion, and electrospinning, novel electrospun polyurethane (PU) membranes with in-situ generated nano-TiO₂ were prepared, which satisfied the requirements of an ideal wound dressing. The morphology of the PU-TiO₂ mats and the cross sectional morphologies of the membranes were characterized by a scanning electron microscopy (SEM). The average diameter of the individual fibers obtained from the solutions was 341±12 nm. SEM micrographs with higher magnification further showed that the in-situ generated TiO₂ particles were well-separated and dispersed homogeneously in the membranes. The average sizes of TiO₂ particles were increased from 31 to 57 nm, with the increase of nano-TiO₂ concentration. The water vapor transmission rates (WVTRs) of the membranes were in the range of 373.55–3121.86 g/m²·d and decreased gradually with the increase of nano-TiO₂ concentration. The water absorption of various PU membranes was in the range of 210.90–397.98 % which was enough to prevent wound beds from exudate accumulation. Shake flask testing indicated that the PU membrane exhibited antibacterial efficiency against Pseudomonas aeruginosa (Ps. aeruginosa) and Staphylococcus aureus (S. aureus) due to in-situ generated of nano-TiO₂. These electrospun nanofibrous membranes also had no toxic effect and showed good and immediate adherence to L929 cells.