Sputter deposition of high transparent TiO2−xNx/TiO2/ZnO layers on glass for development of photocatalytic self-cleaning application

In this study, TiO_2−xN_x/TiO₂ double layers thin film was deposited on ZnO (80 nm thickness)/soda-lime glass substrate by a dc reactive magnetron sputtering. The TiO₂ film was deposited under different total gas pressures of 1 Pa, 2 Pa, and 4 Pa with constant oxygen flow rate of 0.8 sccm. Then, the deposition was continued with various nitrogen flow rates of 0.4, 0.8, and 1.2 sccm in constant total gas pressure of 4 Pa. Post annealing was performed on as-deposited films at various annealing temperatures of 400, 500, and 600 °C in air atmosphere to achieve films crystallinity. The structure and morphology of deposited films were evaluated by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and atomic force microscopy (AFM). The chemical composition of top layer doped by nitrogen was evaluated by X-ray photoelectron spectroscopy (XPS). Photocatalytic activity of samples was measured by degradation of Methylene Blue (MB) dye. The optical transmittance of the multilayer film was also measured using ultraviolet-visible light (UV-vis) spectrophotometer. The results showed that by nitrogen doping of a fraction (∼1/5) of TiO₂ film thickness, the optical transmittance of TiO_2−xN_x/TiO₂ film was compared with TiO₂ thin film. Deposited films showed also good photocatalytic and hydrophilicity activity at visible light.     

Strong‐Base‐Assisted Synthesis of a Crystalline Covalent Triazine Framework with High Hydrophilicity via Benzylamine Monomer for Photocatalytic Water Splitting

Methods to synthesize crystalline covalent triazine frameworks (CTFs) are limited and little attention has been paid to development of hydrophilic CTFs and photocatalytic overall water splitting. A route to synthesize crystalline and hydrophilic CTF‐HUST‐A1 with a benzylamine‐functionalized monomer is presented. The base reagent used plays an important role in the enhancement of crystallinity and hydrophilicity. CTF‐HUST‐A1 exhibits good crystallinity, excellent hydrophilicity, and excellent photocatalytic activity in sacrificial photocatalytic hydrogen evolution (hydrogen evolution rate up to 9200 μmol g^?1 h^?1). Photocatalytic overall water splitting is achieved by depositing dual co‐catalysts in CTF‐HUST‐A1, with H₂ evolution and O₂ evolution rates of 25.4 μmol g^?1 h^?1 and 12.9 μmol g^?1 h^?1 in pure water without using sacrificial agent.     

Switchable‐hydrophilicity solvent liquid‐liquid microextraction versus dispersive liquid‐liquid microextraction prior to HPLC‐UV for the determination and isolation of piperine from Piper nigrum L

Switchable‐hydrophilicity solvent liquid‐liquid microextraction and dispersive liquid‐liquid microextraction were compared for the extraction of piperine from Piper nigrum L. prior to its analysis by using high‐performance liquid chromatography with UV detection. Under optimum conditions, limits of detection and quantitation were found as 0.2–0.6 and 0.7–2.0 μg/mg with the two methods, respectively. Calibration graphs showed good linearity with coefficients of determination (R²) higher than 0.9962 and percentage relative standard deviations lower than 6.8%. Both methods were efficiently used for the extraction of piperine from black and white pepper samples from different origins and percentage relative recoveries ranged between 90.0 and 106.0%. The results showed that switchable‐hydrophilicity solvent liquid‐liquid microextraction is a better alternative to dispersive liquid‐liquid microextraction for the routine analysis of piperine in food samples. A novel scaled‐up dispersive liquid‐liquid microextraction method was also proposed for the isolation of piperine providing a yield of 102.9 ± 4.9% and purity higher than 98.0% as revealed by NMR spectroscopy.     

Reason for the loss of hydrophilicity of TiO_2 film and its photocatalytic regeneration

TiO2 film was prepared on soda-lime glass by sol-gel method. The water contact angle (θ) of the fresh TiO2 film is 0°. During storage in air, the surface of TiO2 film is gradually converted to the hydrophobic state. XPS and ITD results reveal that it is due to the adsorption of organic contaminants on TiO2 surface in air ambience. The lost hydrophilicity of TiO2 film can be regenerated by UV illumination.     

Recent advances in heterogeneous TiO2 photocatalysis

Current progress in the area of photocatalysis is presented, particularly regarding technological applications. Highly efficient TiO₂ films on different substrates such as tile and glass have been developed for indoor environmental clean-up. TiO₂ films coated on SiO₂-precoated soda lime glass showed about 80% transparency and high photocatalytic activity towards the decomposition of thin oil films. A novel phenomenon, superhydrophilicity, has been observed on these transparent TiO₂ coatings. In addition, we have made use of a microelectrode system to monitor oxidation and reduction products separately. The mechanistic and kinetic aspects of TiO₂ photocatalysis are discussed.     

Thermal behaviour study of some sol-gel TiO2 based materials

Among the great number of sol-gel materials prepared, TiO₂ holds one of the most important places due to its photocatalytic properties, both in the case of powders and coatings. Impurity doping is one of the typical approaches to extend the spectral response of a wide band gap semiconductor to visible light. This work has studied some un-doped and Pd-doped sol-gel TiO₂ nanopowders, presenting various surface morphologies and structures. The obtained powders have been embedded in vitreous TiO₂ matrices and the corresponding coatings have been prepared by dipping procedure, on glass substrates. The relationship between the synthesis conditions and the properties of titania nanosized materials, such as thermal stability, phase composition, crystallinity, morphology and size of particles, and the influence of dopant was investigated. The influence of Pd on TiO₂ crystallization both for supported and unsupported materials was studied (lattice parameters, crystallite sizes, internal strains). The hydrophilic properties of the films were also connected with their structure, composition and surface morphology. The methods used for the characterization of the materials have been: simultaneous thermogravimetry and differential thermal analysis, powder X-ray diffraction, electron microscopy (TEM, SAED) and AFM.     

Modification effects of amphiphilic comb-like polysiloxane containing polyether side chains on the PVDF membranes prepared via phase inversion process

Amphiphilic comb-like polysiloxane (ACPS) containing polyether side chains was used as the modification reagent in the preparation of hydrophilic porous poly (vinylidene fluoride) (PVDF) membranes via a phase inversion process. The effects of ACPS on morphology, crystallinity, mechanical properties, reservation of ACPS in the phase inversion process, chemical structure, hydrophilicity and filterability performance of porous PVDF membranes were discussed. It was found that the addition of ACPS would result in the delayed demixing which yields “sponge-like” sublayers and longer crystallization time during the membrane formation process. It was revealed that O/F ratios of the bulk membrane were almost the same as those of the corresponding casting solutions which obviously indicated the high reservation of ACPS in the membrane formation process. The fact that the O/F ratios in the membrane surface layers were much higher than those in the bulk membrane proved the enrichment of ACPS on the surface. The filterability experiments and water contact angle testing proved the hydrophilicity of the blend membranes. Through a schematic model, the mechanism relating the membrane structure and performance was interpreted. From the observed results, it can be concluded that ACPS acts as a potential candidate material for preparing PVDF membranes with extraordinary hydrophilicity and filterability. __________ Translated from Acta Polymerica Sinica, 2007, 12: 1168–1175     

The effect of solvent composition on vancomycin hydrochloride and free base vancomycin release from in situ forming implants

In situ forming drug delivery systems that are formed by solvent‐induced phase inversion have attracted extensive attention in sustained delivery of peptides and proteins. Based on the findings of our previous studies, N‐methyl‐2‐pyrrolidone (NMP) and acetone are two solvents that could improve the release profile of vancomycin from in situ forming systems based on poly(D,L‐lactide‐co‐glycolic acid). In this study, the effect of different compositions of these solvents on the release profile of hydrochloride and free base forms of vancomycin was investigated. To this end, several formulations with vancomycin (either hydrochloride or free base form) and different proportions of NMP and acetone were prepared. The cumulative drug release at specified time was determined and tested against conventional kinetic models. The surface and cross‐sectional morphology of implants were investigated by SEM. The experimental results showed that as solvent composition changed, the amount of vancomycin release during the first 12 h changed, too. The use of free base vancomycin resulted in an extended vancomycin release profile with less initial burst release. The formulation containing free base vancomycin and mixed solvents of acetone and NMP in 2:1 ratio released 70% of loaded drug in 6 weeks with near zero‐order kinetic. The best kinetic model to fit the in vitro release profiles was found to be Peppas–Sahlin model. Copyright © 2016 John Wiley & Sons, Ltd.     

Improved Hydrophobicity of Macroalgae Biopolymer Film Incorporated with Kenaf Derived CNF Using Silane Coupling Agent

Hydrophilic behaviour of carrageenan macroalgae biopolymer, due to hydroxyl groups, has limited its applications, especially for packaging. In this study, macroalgae were reinforced with cellulose nanofibrils (CNFs) isolated from kenaf bast fibres. The macroalgae CNF film was after that treated with silane for hydrophobicity enhancement. The wettability and functional properties of unmodified macroalgae CNF films were compared with silane-modified macroalgae CNF films. Characterisation of the unmodified and modified biopolymers films was investigated. The atomic force microscope (AFM), SEM morphology, tensile properties, water contact angle, and thermal behaviour of the biofilms showed that the incorporation of Kenaf bast CNF remarkably increased the strength, moisture resistance, and thermal stability of the macroalgae biopolymer films. Moreover, the films’ modification using a silane coupling agent further enhanced the strength and thermal stability of the films apart from improved water-resistance of the biopolymer films compared to unmodified films. The morphology and AFM showed good interfacial interaction of the components of the biopolymer films. The modified biopolymer films exhibited significantly improved hydrophobic properties compared to the unmodified films due to the enhanced dispersion resulting from the silane treatment. The improved biopolymer films can potentially be utilised as packaging materials.     

Surface roughness and hydrophilicity enhancement of polyolefin‐based membranes by three kinds of plasma methods

The introduction of antibacterial property, conductivity, wettability and antithrombogenicity into polyolefin‐based membranes has evoked much attention, which can be achieved by coating hydrophilic polymers. Therefore, it is necessary to modify the roughness and hydrophilicity of polyolefin‐based membranes to enhance the coating ability. In this paper, three kinds of plasma methods, including inductively coupled (ICP) plasma, radio frequency low pressure (RFP) plasma and atmospheric dielectric barrier discharge (DBD) plasma, were used to modify the surface of the polyethylene (PE), polypropylene (PP) and polyester‐polypropylene (PET–PP) membranes. The surface roughness of the plasma‐modified PE, PP and PET–PP films was investigated by scanning electron microscopy (SEM) and atomic force microscope (AFM). The polar functional groups of films were observed by energy dispersive spectrometer (EDX) and X‐ray photoelectron spectroscopy (XPS). Besides, the hydrophilicity of the plasma‐modified PE, PP and PET–PP films was evaluated by water contact angle measurement. It was found that the surface roughness and hydrophilicity of plasma‐modified PE, PP and PET–PP films increased with the generation of oxygen‐containing functional groups (i.e. C―O, and C?O). The PET–PP membranes were treated by RFP plasma at different processing powers and times. These results indicated that plasma is an effective way to modify films, and the treatment time and power of plasma had a certain accumulation effect on the membranes' hydrophilicity. As for the roughness and hydrophilicity, the DBD plasma modifies the PE film, which is the optimum way to get the ideal roughness and hydrophilicity. Copyright © 2015 John Wiley & Sons, Ltd.