Superhydrophobic cotton fabric fabricated by electrostatic assembly of silica nanoparticles and its remarkable buoyancy

Highly hydrophilic cotton fabrics were rendered superhydrophobic via electrostatic layer-by-layer assembly of polyelectrolyte/silica nanoparticle multilayers on cotton fibers, followed with a fluoroalkylsilane treatment. The surface morphology of the silica nanoparticle-coated fibers, which results in the variety of the hydrophobicity, can be tailored by controlling the multilayer number. Although with the static contact angle larger than 150°, in the case of 1 or 3 multilayers, the fabrics showed sticky property with a high contact angle hysteresis (>45°). For the cotton fabrics assembled with 5 multilayers or more, slippery superhydrophobicity with a contact angle hysteresis lower than 10° was achieved. The buoyancy of the superhydrophobic fabric was examined by using a miniature boat made with the fabric. The superhydrophobic fabric boat exhibited a remarkable loading capacity; for a boat with a volume of 8.0 cm³, the maximum loading was 11.6 or 12.2 g when the boat weight is included. Moreover, the superhydrophobic cotton fabric showed a reasonable durability to withstand at least 30 machine washing cycles.     

Fabrication of superhydrophobic cotton fabrics by silica hydrosol and hydrophobization

Superhydrophobic cotton fabrics were prepared by the incorporation of silica nanoparticles and subsequent hydrophobization with hexadecyltrimethoxysilane (HDTMS). The silica nanoparticles were synthesized via sol-gel reaction with methyl trimethoxy silane (MTMS) as the precursor in the presence of the base catalyst and surfactant in aqueous solution. As for the resulting products, characterization by particle size analyzer, scanning electron microscopy (SEM), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and thermal gravimetric analysis (TGA) were performed respectively. The size of SiO₂ nanoparticles can be controlled by adjusting the catalyst and surfactant concentrations. The wettability of cotton textiles was evaluated by the water contact angle (WCA) and water shedding angle (WSA) measurements. The results showed that the treated cotton sample displayed remarkable water repellency with a WCA of 151.9° for a 5 μL water droplet and a WSA of 13° for a 15 μL water droplet.     

Direct chemical assembly of quaternary ammonium groups on a surface of highly dispersed silica

Direct assembly of quaternary ammonium groups onto a silica surface has been realized by use of many-stage chemical reactions. Adsorption of cholic acid in dependence on duration, equilibrium concentration, and pH solution onto a surface of silicas modified with quaternary ammonium groups has been studied. The main parameters of cholic acid adsorption have been calculated.     

Ultrasound irradiation based in-situ synthesis of star-like Tragacanth gum/zinc oxide nanoparticles on cotton fabric

Application of natural biopolymers for green and safe synthesis of zinc oxide nanoparticles on the textiles is a novel and interesting approach. The present study offers the use of natural biopolymer, Tragacanth gum, as the reducing, stabilizing and binding agent for in-situ synthesis of zinc oxide nanoparticles on the cotton fabric. Ultrasonic irradiation leads to clean and easy synthesis of zinc oxide nanoparticles in short-time at low-temperature. FESEM/EDX, XRD, FT-IR spectroscopy, DSC, photocatalytic activities and antimicrobial assay are used to characterize Tragacanth gum/zinc oxide nanoparticles coated cotton fabric. The analysis confirmed synthesis of star-like zinc oxide nanoparticles with hexagonal wurtzite structure on the cotton fabric with the average particle size of 62 nm. The finished cotton fabric showed a good photocatalytic activity on degradation of methylene blue and 100% antimicrobial properties with inhibition zone of 3.3 ± 0.1, 3.1 ± 0.1 and 3.0 ± 0.1 mm against Staphylococcus aureus, Escherichia coli and Candida albicans.     

Ultrasound mediation for one-pot sonosynthesis and deposition of magnetite nanoparticles on cotton/polyester fabric as a novel magnetic,photocatalytic, sonocatalytic,antibacterial and antifungal textile

A magnetic cotton/polyester fabric with photocatalytic, sonocatalytic, antibacterial and antifungal activities was successfully prepared through in-situ sonosynthesis method under ultrasound irradiation. The process involved the oxidation of Fe²⁺ to Fe³⁺ via hydroxyl radicals generated through bubbles collapse in ultrasonic bath. The treated samples were analyzed by X-ray diffraction, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and vibrating sample magnetometry. Photocatalytic and sonocatalytic activities of magnetite treated fabrics were also evaluated toward Reactive Blue 2 decoloration under sunlight and ultrasound irradiation. Central composite design based on response surface methodology was applied to study the influence of iron precursor, pH and surfactant concentration to obtain appropriate amount for the best magnetism. Findings suggested the potential of one-pot sonochemical method to synthesize and fabricate Fe₃O₄ nanoparticles on cotton/polyester fabric possessing appropriate saturation magnetization, 95% antibacterial efficiency against Staphylococcus aureus and 99% antifungal effect against Candida albicans, 87% and 70% dye photocatalytic and sonocatalytic decoloration along with enhanced mechanical properties using only one iron rich precursor at low temperature.     

Multiferroic based on nanoparticles consisting of a silica nucleus and a shell of spin-variable iron complexes

Cholesteric droplets dispersed in a polymer with homeotropic surface anchoring are studied. A director configuration with the bipolar distribution of the axis of the helix is formed in droplets. The untwisting of the helical structure (i.e., an increase in the pitch of the helix) is experimentally observed at a decrease in the size of droplets. This dependence is analyzed for liquid crystal droplets with various concentrations of the chiral addition. A proposed empirical relation describes well the correlation of the helix pitch and the size of droplets in the studied samples.     

Chemical modification of metal oxide carrier's surfaces with a silane coupling agent and an application of the method to catalyst preparation

Several metal oxides were modified with γ-anilinopropyltrimethoxysilane (AnPS). Variations in the physicochemical properties with the modification were investigated in detail. The adsorptivity of 12-tungstophosphate anion (PW12) was shown to be greatly improved in the carriers such as SiO₂, TiO₂, and Al₂O₃, which are porous and have a high surface area, but it was not increased in SnO₂ and MgO, which have a small surface area and a high isoelectric point. With TiO₂-carrier, quantitative studies on the adsorptivity were carried out further, and the interaction modes of PW12 on the AnPS-modified surfaces were discussed based on FT-IR and XPS analyses. The isotherm attained quite steeply to a monomolecular layer of PW12. The FT-IR bands ascribed to the anilino group deformed considerably and the N1s-peak in XPS shifted along with the PW12-adsorption. From the findings it was strongly suggested that PW12 was effectively fixed through an acid–base interaction on the AnPS-TiO₂. Catalytic activity of PW12 fixed on AnPS-TiO₂ for 2-propanol dehydration as a test reaction were examined; in the pretreatment at 300°C the activity was limited to a low level but after the treatment at 450°C it increased in proportion to the PW12-loading on the AnPS-TiO₂ surfaces. Thus, it was inferred that PW12 was quite regularly dispersed over the modified surface. In conclusion, it is suggested that the modification technique is applicable to the preparation of a metal oxide–supported heteropolyacid catalyst.     

Structural optimization and segregation behavior of quaternary alloy nanoparticles based on simulated annealing algorithm

Alloy nanoparticles exhibit higher catalytic activity than monometallic nanoparticles, and their stable structures are of importance to their applications. We employ the simulated annealing algorithm to systematically explore the stable structure and segregation behavior of tetrahexahedral Pt–Pd–Cu–Au quaternary alloy nanoparticles. Three alloy nanoparticles consisting of 443 atoms, 1417 atoms, and 3285 atoms are considered and compared. The preferred positions of atoms in the nanoparticles are analyzed. The simulation results reveal that Cu and Au atoms tend to occupy the surface, Pt atoms preferentially occupy the middle layers, and Pd atoms tend to segregate to the inner layers. Furthermore, Au atoms present stronger surface segregation than Cu ones. This study provides a fundamental understanding on the structural features and segregation phenomena of multi-metallic nanoparticles.     

Network structure consisting of chain-like arrays of gold nanoparticles and silica layer prepared using a nonionic reverse-micelle template

A nonionic reverse-micelle based approach is described for fabrication of a network structure consisting of chain-like arrays of gold nanoparticles, followed by coating process with a uniform silica layer using a sol-gel method. The hexadecyl-poly (ethylene oxide-15) ether (designated C₁₆E₁₅) is used as a template for this study. The effects of a water-to-surfactant molar ratio (w) as well as the concentration of tetraethyl orthosilicate ([TEOS]_oil) are investigated on the resulting organized structures.     

Blue organic electroluminescent devices based on a distyrylarylene derivative as emitting layer and a terbium complex as electron-transporting layer

With a blue distyrylarylene derivative, 4,4′-bis(2,2-di(2-methoxyphenyl)ethenyl)-1,1′-biphenyl (CBS) as emitting material, double-layer and triple-layer electroluminescent (EL) devices were fabricated. For the device using tris-(1-phenyl-3-methyl-4-isobutyryl-5-pyrozolone)-bis(triphenyl phosphine oxide) terbium (Tb(PMIP)₃(TPPO)₂) as the electron-transporting layer, blue EL emission with a maximum luminance of 253 cd/m² was achieved at 19 V. The difference of Tb(PMIP)₃(TPPO)₂ and tris(8-hydroxyquinolinate)aluminum (AlQ) as the electron-transporting materials in these devices were compared and discussed.     

Preparation and characterization of a novel antistatic poly(vinyl chloride)/quaternary ammonium based ion-conductive acrylate copolymer composites

Antistatic poly(vinyl chloride)/quaternary ammonium salt based ion-conductive acrylate copolymer (PVC/QASI) composites were successfully prepared in a Haake torque rheometer. The surface resistivity of the PVC/QASI composites could be reduced to 10⁷ Ω sq^?1 order of magnitude when the QASI content reached 20 phr (parts per hundreds of resin). The surface resistivity of the composites was slightly sensitive to the relative humidity (RH), showing a good antistatic ability under an RH of 12%. Mechanical properties tests, differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were also used to investigate the tensile strength, elongation at break, thermal properties, and morphology of the PVC/QASI composites, respectively.     

Effect of sintering temperature on mechanical behaviour and bioactivity of sol-gel synthesized bioglass-ceramics using rice husk ash as a silica source

Bioglass-ceramics with SiO₂-Na₂O-CaO composition was prepared by sol-gel method using rice husk ash as a silica source. Material was sintered at different temperatures ranging from 900 to 1050 °C for 2 h. Phase-formation behaviour, densification characteristics, and mechanical strength of glass-ceramics were investigated. The material sintered at 1000 °C showed a good mechanical strength. Mechanical properties were correlated with microstructural features. Both in vitro bioactivity and biodegradability of sintered material were investigated by incubating in simulated body fluid and Tris buffer solution, respectively. Scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction were used to investigate the surface deposition during body fluid incubation. Both bioactivity and degradability decreased with increase in sintering temperature.     

Comparison of ZnO thin films grown on a polycrystalline 3C-SiC buffer layer by RF magnetron sputtering and a sol-gel method

Zinc oxide (ZnO) thin films were deposited on a polycrystalline (poly) 3C-SiC buffer layer using RF magnetron sputtering and a sol-gel method. The post-deposition annealing was performed on ZnO thin films prepared using both methods. The formation of ZnO piezoelectric thin films with less residual stress was due to a close lattice mismatch of the ZnO and SiC layers as obtained by the sputtering method. Nanocrystalline, porous ZnO film prepared using the sol-gel method showed strong ultraviolet UV emission at a wavelength of 380 nm. The 3C-SiC buffer layer improved the optical and piezoelectric properties of the ZnO film produced by the two deposition methods. Moreover, the different structures of the ZnO films on the 3C-SiC intermediate layer caused by the different deposition techniques were also considered and discussed.     

The effects of activated carbon supports on the structure and properties of TiO2 nanoparticles prepared by a sol-gel method

TiO₂-coated activated carbon (TiO₂/AC) composites and pure TiO₂ powders were prepared by a sol-gel method using tetrabutylorthotitanate as a precursor. The samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential thermal analysis (DTA), X-ray photoelectron spectrum (XPS) and nitrogen absorption. The photoactivity of samples was evaluated by methylene blue (MB) degradation. The analysis results show that compared with pure TiO₂ powders, the spherical-shaped TiO₂ particles are well-dispersed in the AC matrix and the size of the resulting TiO₂ crystallites decreases to below 40 nm with increasing phase transformation temperature. The AC matrix creates anti-calcination effects and shows interfacial energy effects that control the growth of the TiO₂ particles, baffle the anatase to rutile phase transition, and cumber the TiO₂ particles to agglomerate. Compared with the surface areas of TiO₂ powders, the combination of TiO₂ and AC forms composites with high surface areas which are slightly affected by calcination temperature. By AC support, the photoactivity of TiO₂ is increased in MB photocatalytic course, possible because active carbon increases photocatalytic activity of TiO₂ particles by producing high concentration of organic compound near TiO₂, and small-size TiO₂ particles are well-dispersed on the surface of AC.     

Fabrication of superhydrophobic coating via a facile and versatile method based on nanoparticle aggregates

Herein, we report a facile and low cost method for the fabrication of superhydrophobic surface via spin coating the mixture of polydimethylsiloxane precursor (PDMS) and silicon dioxide (SiO₂) nanoparticles. The surface hydrophobicity can be well tuned by adjusting the weight percent of PDMS and SiO₂. The water contact angle (WCA) can increase from 106.8 ± 1.2° on PDMS film to 165.2 ± 2.3° on PDMS/SiO₂ coating, companying with a change from adhering to rolling which was observed from tilting angle (TA) characterization. Multi-scale physical structures with SiO₂ nanoparticle aggregates and networks of SiO₂ nanoparticle aggregates are characterized by scanning electron microscopy (SEM) and atomic force microscope (AFM), and they can be observed more clearly from the AFM images treated with software (WSxM). Then the relationship between surface hydrophobicity and structures is further discussed based on Wenzel and Cassie models, indicating that the appearance of networks of nanoparticle aggregates is important in the Cassie state. The superhydrophobic coating can keep the superhydrophobicity at least for one month under environment conditions and readily regenerate after mechanical damage. Additionally, the superhydrophobic coating can be fabricated using other methods including dip coating, spray coating and casting. Thus, a large area of superhydrophobic coatings can be easily fabricated. Therefore the range of possible applications for these facile and versatile methods can be expanded to various actual conditions.     

Synthesis and characterization of a novel two-component organogelator based on ion-bonded discotic complex

A novel ion-bonded discotic complex was prepared from 2,3,6,7,10,11-hexakis(N,N-dimethylaminopropylaminocarbonylmethoxy)triphenylene (HDTP) and 4′-dodecyloxybiphenyl-4-carboxylic acid (DBC) by ionic self-assembly (ISA) route and characterized by Fourier transform infrared (FTIR) spectrum. We found that the complex can self-assemble into stable gels in aromatic hydrocarbons. Nanofibers with diameters of 50–130 nm were observed in the gels by transmission electron micrograph (TEM). The FTIR data in conjunction with UV–vis and fluorescence spectra suggested that the aggregation of the complex into elongated fibers in solution was induced by a directional extended network of hydrogen bonds and π–π interactions. Based on the experiment analysis, we proposed a tentative model of the self-assembly of this two-component gel-phase material.     

Synthesis and properties of magnetic fluid based on iron nanoparticles prepared by a vapor-phase condensation process

Magnetic fluid containing metallic iron nanoparticles was successfully fabricated in this work. The iron nanoparticles were synthesized by chemical vapor condensation process and then dispersed in water-base solution (pH 11) with oleic acid as surfactant. More than 80% of iron nanoparticles were fully dispersed in the fluid and remained stable without any further oxidation over 200 h. Both the iron nanoparticles and the subsequent magnetic fluid exhibited typical ferromagnetic behavior.     

Polyamorphism of liquid silica under compression based on five order-parameters and two-state model: a completed and unified description

The polyamorphism of liquid silica (SiO₂) at 3200?K and in a wide pressure range is investigated by molecular dynamics simulation. Results show that the structure of liquid SiO₂ consists of five order-parameters that do not depend on compression. Three order parameters that relate to the short-range order are SiO_x coordination units (x?=?4, 5, 6) and two order parameters that relate to the intermediate-range order are OSi₂ and OSi₃ linkages. The structure of liquid silica under compression can be described by the two-state model: low-density and high-density states. The low-density state is formed by clustering of OSi₂ linkages (in the low-density state, the short-range order (SRO) is mainly characterized by SiO₄ coordination units), conversely, clustering of OSi₃ linkages will form high-density state (in the high-density state, the SRO is mainly characterized by SiO₅ and SiO₆ coordination units). Under compression, in the liquid silica co-exist two phases: low-density and high-density phases. The size of phase regions significantly depends on compression.     

用RC电路测量并分析介电频率谱

介绍了用自搭式RC电路测量电介质介电频率谱的方法,并对样品PZT5介电谱的两个谐振峰做了分析.与精密的阻抗分析仪的测量结果相比较,证明该实验方法可行.     

SERS study of a tetrapeptide based on histidine and glycine residues,adsorbed on copper/silver colloidal nanoparticles

Surface‐enhanced Raman scattering has been employed to characterize the adsorption of an oligopeptide containing histidine residues on colloidal nanoparticles of metals as Ag and Cu obtained by laser ablation. The title molecule consists of two histidine and glycine residues alternating along the chain and terminating with an acetyl on one side and an amide group on the other. Histidine residues are found to act as docking sites of the molecule to the surface of the metal nanoparticles. Semiempirical parameterized model number 3 (PM3) calculations performed on molecule/metal model complexes suggest possible different adsorption geometries depending on the metallic substrate. This investigation could provide useful information to address the interaction of protein systems with metal ions, which is often related to fundamental biological process in living systems and can play an important role in different neuropathological diseases. Copyright © 2014 John Wiley & Sons, Ltd.