Preparation and characterization of bipolar membranes modified using photocatalyst nano‐TiO2 and nano‐ZnO

The nano‐ZnO and nano‐TiO₂ were added into chitosan (CS) anion layer to prepare polyvinyl alcohol (PVA) ‐ sodium alginate (SA)/ TiO₂‐ZnO‐CS (here, PVA:polyvinyl alcohol; SA:sodium alginate) bipolar membrane (BPM), which was characterized using scanning electron microscopy, atomic force microscopy (AFM), thermogravimetric analysis (TG), electric universal testing machine, contact angle measurer, and so on. Experimental results showed that nano‐TiO₂‐ZnO exhibited better photocatalytic property for water splitting at the interlayer of BPM than nano‐TiO₂ or nano‐ZnO. The membrane impedance and voltage drop (IR drop) of the BPM were obviously decreased under the irradiation of high‐pressure mercury lamps. At a current density of 60 mA/cm², the cell voltage of PVA‐SA/TiO₂‐ZnO‐CS BPM‐equipped cell decreased by 1.0 V. And the cell voltages of PVA‐SA/TiO₂‐CS BPM‐equipped cell and PVA‐SA/ZnO‐CS BPM‐equipped cell were only reduced by 0.7 and 0.6 V, respectively. Furthermore, the hydrophilicity, thermal stability, and mechanical properties of the modified BPM were increased. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation of poly(vinyl alcohol)/poly(acrylic acid)/TiO2/carbon nanotube composite nanofibers and their photobleaching properties

The composite nanofibers of poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAAc)/titanium(IV) oxide (TiO₂) were prepared by electrospinning for a novel photocatalytic treatment of waste water. To improve the photoelectronic properties of PVA/PAAc/TiO₂ composite nanofibers, carbon nanotubes (CNTs) were used as an additive. The TiO₂ and CNTs were immobilized in the PVA/PAAc hydrogels as electrospun nanofibers for an easier recovery after the wastewater treatment. The improved efficiency of pollutant dye removal was observed at pH 10 due to the pH-sensitive swelling behavior of the PVA/PAAc/TiO₂/CNTs composite nanofibers. The photocatalytic activity of TiO₂ was improved noticeably by applying electric field to the CNTs-embedded composite nanofibers.     

Synthesis,physical properties,and characterization of starch‐based blend films by adding nano‐sized TiO2/poly(methyl metacrylate‐co‐acrylamide)

The purpose of this study was to improve the physical properties and to expand the application range of starch‐based blend films added nano‐sized TiO₂/poly(methyl methacrylate‐co‐acrylamide) (PMMA‐co‐AM). Starch‐based blend films were prepared by using corn starch, polyvinyl alcohol (PVA), nano‐sized PMMA‐co‐AM, nano‐sized TiO₂/PMMA‐co‐AM particles, and additives, i.e., glycerol (GL) and citric acid (CA). Nano‐sized PMMA‐co‐AM was synthesized by emulsion polymerization and TiO₂ nanoparticles were also prepared by using sol–gel method. Nano‐sized TiO₂/PMMA‐co‐AM particles were synthesized by wet milling for 48 h. The morphology and crystallinity of TiO₂, nano‐sized PMMA‐co‐AM and TiO₂/PMMA‐co‐AM particles were investigated by using the scanning electron microscope (SEM) and X‐ray diffractometer (XRD). In addition, the functional groups of the TiO₂/PMMA‐co‐AM particles were characterized by IR spectrophotometry (FTIR). The physical properties such as tensile strength (TS), elongation at break (%E), degree of swelling (DS), and solubility (S) of starch‐based films were evaluated. It was found that the adding of nano‐sized particles can greatly improve the physical properties of the prepared films. The photocatalytic degradability of starch/PVA/nano‐sized TiO₂/PMMA‐co‐AM composite films was evaluated using methylene blue (MB) and acetaldehyde (ATA) as photodegradation target under UV and visible light. The degree of decomposition (C/C₀) of MB and ATA for the films containing TiO₂ and CA was 0.506 and 0.088 under UV light irradiation and 0.586 (MB) and 0.631 (ATA) under visible light irradiation, respectively. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Preparation and characterization of graphene oxide/poly(vinyl alcohol) composite nanofibers via electrospinning

Graphene oxide (GO) was well dispersed in poly(vinyl alcohol) (PVA) diluted aqueous solution, and then the mixture was electrospun into GO/PVA composite nanofibers. Electron microscopy and Raman spectroscopy on the as‐prepared and calcined samples confirm the uniform distribution of GO sheets in the nanofibers. The thermal and mechanical properties of the nanofibers vary considerably with different GO filler contents. The decomposition temperatures of the GO/PVA composite nanofiber dropped by 38–50°C compared with pure PVA. A very small loading of 0.02 wt % GO increases the tensile strength of the nanofibers by 42 times. A porous 3D structure was realized by postcalcining nanofibers in H₂. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Preparation and photoluminescent characterization of poly(phenylene vinylene)/TiO2 nanoparticles composite nanofibers by one‐step electrospinning

A simple electrospinning progress, directly mixing method, was used to produce ultrafine poly(phenylene vinylene)/TiO₂ (PPV/TiO₂) composite nanofibers with diameters ranging from 100 to 300 nm. The effects of different TiO₂ content on diameter, morphology, and structure of composite fibers were analyzed by scanning electron microscopy and transmission electron microscope. The results showed that composite polymer nanofibers with smooth surface were obtained when TiO₂ concentration was below 18 wt %. The surface of the composite nanofibers became rougher with the increase of TiO₂ content. The optical properties of the as‐prepared nanofibers were characterized by photoluminescence spectra and photographs, the results showed an increase in intensity of the high‐energy shoulder (510 nm) when the concentration of nanoparticles increased. X‐ray diffraction measurements showed that the increasing TiO₂ content enhanced the amorphous phase of PPV in composite nanofibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Study of the effect of rutile/anatase TiO2 nanoparticles synthesized by hydrothermal route in electrospun PVA/TiO2 nanocomposites

Mixed rutile–anatase TiO₂ nanoparticles were synthesized by hydrothermal treatment under acidic conditions and incorporated into poly(vinyl alcohol) (PVA). These nanocomposites were electrospun to produce nanofibers of PVA/TiO₂, which were characterized by scanning electron microscopy, transmission electron microscopy, X‐ray diffraction (XRD), UV–vis diffuse reflectance spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The photocatalytic degradation of Rhodamine B and degradation of the polymer by UV‐C lamps were also investigated. The results showed that TiO₂ nanoparticles did not change the morphology and thermal behavior of the nanofiber polymer, but were effective in modifying the UV absorption of PVA without reducing its stability. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Photosensitive antibacterial and cytotoxicity performances of a TiO2/carboxymethyl chitosan/poly(vinyl alcohol) nanocomposite hydrogel by in situ radiation construction

Nano‐TiO₂/carboxymethyl chitosan (CMCS)/poly(vinyl alcohol) (PVA) ternary nanocomposite hydrogels were prepared by freezing–thawing cycles and electron‐beam radiation with PVA, CMCS, and nano‐TiO₂ as raw materials. The presence of nano‐TiO₂ nanoparticles in the composite hydrogels was confirmed by thermogravimetry, Fourier transform infrared spectroscopy, and X‐ray powder diffraction. Field emission scanning electron microscopy images also illustrated that the TiO₂/CMCS/PVA hydrogel exhibited a porous and relatively regular three‐dimensional network structure; at the same time, there was the presence of embedded nano‐TiO₂ throughout the hydrogel matrix. In addition, the nano‐TiO₂/CMCS/PVA composite hydrogels displayed significant antibacterial activity with Escherichia coli and Staphylococcus aureus as bacterial models. The antibacterial activity was demonstrated by the antibacterial circle method, plate count method, and cell density method. Also, with the Alamar Blue assay, the cytotoxicity of the composite hydrogel materials to L929 cells was studied. The results suggest that these materials had no obvious cytotoxicity. Thus, we may have developed a novel, good biocompatibility hydrogel with inherent photosensitive antibacterial activity with great potential for applications in the fields of cosmetics, medical dressings, and environmental protection. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44150.     

Effects of nano‐tio2 on the performance of high‐amylose starch based antibacterial films

The purpose of this article is to investigate the effects of nano‐tianium dioxide (nano‐TiO₂) on the high‐amylose starch/polyvingl alcohol (PVA) blend films prepared by a solution casting method. The results show that at the concentration of 0.6% of nano‐TiO₂, the film demonstrated the best tensile strength at 9.53 MPa, and the elongation at break was noted as 49.50%. The optical transmittance of the film was decreased and the water resistance was improved with further increase of the concentration of nano‐TiO₂. Using the techniques of Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), and field‐emission scanning electron microscopy (SEM), the molecular and the crystal structures of the films were characterized. The results indicate that the miscibility and compatibility between high‐amylose starch and PVA were increased with the addition of nano‐TiO₂ into the films due to the formation of hydrogen and C? O? Ti bonds. The antimicrobial activities of the blend films were also explored. The results show that there were inhibitory zones around the circular film disc, which is attributable to the addition of nano‐TiO₂. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42339.     

Antibacterial electrospun chitosan/poly(vinyl alcohol) nanofibers containing silver nitrate and titanium dioxide

Chitosan/poly(vinyl alcohol) (PVA) nanofibers with antibacterial activity were prepared by the electrospinning of a chitosan/PVA solution with a small amount of silver nitrate (AgNO₃) and titanium dioxide (TiO₂). Nanofibers with diameters of 270–360 nm were obtained. The yield of low‐viscosity chitosan (LCS)/PVA nanofibers was higher than that of high‐viscosity chitosan (HCS)/PVA, and the water content of the HCS/PVA nanofibers and the LCS/PVA nanofibers were 430 and 390%, respectively. The nanofibers developed in this study exhibited antibacterial activities of 99 and 98% against Staphylococcus aureus and Escherichia coli, respectively. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Electrospinning preparation and characterization of cadmium oxide nanofibers

Using a facile synthesis route, cadmium oxide (CdO) nanofibers in the diameter range of 50–60 nm have been prepared employing the electrospinning technique followed by a single-step calcination from the aqueous solution of polyvinyl alcohol (PVA) and cadmium acetate dihydrate. Electron microscopy (EM) and the Brunauer–Emmett–Teller (BET) technique were employed to characterize the as-spun nanofibers as well as the calcined product. The specific surface area of the product was calculated to be 42.6711 m² g⁻¹. Infrared (IR) absorbance spectroscopy and X-ray powder diffractometery were conducted on the samples to study their chemical composition as well as their crystallographic structure. The study on the optical properties based on the photoluminescence (PL) spectrum demonstrated that the emission peaks of CdO nanofibers are centered at 493 and 528 nm. The direct bandgap of the CdO nanofibers was determined to be 2.51 eV.     

A starch‐based biodegradable film modified by nano silicon dioxide

The purpose of this work was to improve the properties of the starch/poly(vinyl alcohol) (PVA) films with nano silicon dioxide (nano SiO₂). Starch/PVA/nano‐SiO₂ biodegradable blend films were prepared by a solution casting method. The characteristics of the films were assessed by Fourier Transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The results obtained in this study indicated that the nano‐SiO₂ particles were dispersed evenly within the starch/PVA coating and an intermolecular hydrogen bond and a strong chemical bond C? O? Si were formed in the nano‐SiO₂ and starch/PVA. That the blending of starch, PVA and nano‐SiO₂ particles led to uniform starch/PVA/nano‐SiO₂ blend films with better mechanical properties. In addition, the nano‐SiO₂ particles can improve the water resistance and light transmission of the blend films. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation of atactic poly(vinyl alcohol)/silver composite nanofibers by electrospinning and their characterization

Poly(vinyl alcohol) (PVA)/silver composite nanofibers were successfully prepared by the electrospinning method. Water‐based colloidal silver in a PVA solution was directly mixed without any chemical or structural modifications into PVA polymer fibers to form organic–inorganic composite nanofibers. The ratio of silver colloidal solution to PVA played an important role in the formation of the PVA/silver composite nanofibers. We prepared two different atactic PVA/silver nanocomposites with number‐average degrees of polymerization of 1700 and 4000 through electrospinning with various processing parameters, such as initial polymer concentration, amount of silver colloidal solution, applied voltage, and tip‐to‐collector distance. The PVA/silver composite nanofibers were characterized by field emission scanning electron microscopy and transmission electron microscopy (TEM). TEM images showed that silver nanoparticles with an average diameter of 30–50 nm were obtained and were well distributed in the PVA nanofibers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

A novel mass production method for Li2TiO3 tritium breeder ceramic pebbles using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) assisted granulation method

A novel mass production method of lithium titanite (Li₂TiO₃) tritium breeder ceramic pebbles using polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP) assisted granulation method (APG) was proposed. A binder solution of polyvinyl alcohol (PVA) was used to modify the Li₂TiO₃ precursor powder. The powders with adhesive properties were prilled to form green pebbles (GPs) by spheronization at a low rotation speed and spraying with polyvinyl pyrrolidone (PVP), in several cycles. Then, the density and the crush load of the GPs were improved by high-speed rolling. Finally, the ceramic pebbles were produced by sintering. The phase, the microstructure, and the crush load of the ceramic pebbles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and with a universal tester, respectively.     

Preparation of renewable porous TiO<Subscript>2</Subscript>/PVA composite sphere as photocatalyst for methyl orange degradation

Firstly, preparation of porous polyvinyl alcohol (PVA) spheres were investigated in detail by phase inversion method using N,N-dimethylacetamide (DMAc) and polyvinylpyrrolidone (PVP) as pore-forming additives. The morphology and pore structure of PVA spheres were characterized by SEM and BET measurements. It was found that the addition of DMAc and PVP increased the pore volume and the surface pore size of PVA sphere respectively. The maximum surface area of the porous PVA sphere reached 220 m²/g. Secondly; the synthesis of photoactive TiO₂ NPs (anatase type) at the low temperature was developed by controlling the aging process of the TiO₂ precursors. The crystallinity and photoactivity of TiO₂ NPs increased with the aging time. Finally, TiO₂ NPs/PVA composite spheres were prepared by immersing PVA sphere into TiO₂ precursor solution. Their structures were characterized by XRD pattern, TEM and TGA measurement. It was found that TiO₂ NPs were successfully immobilized into PVA spheres. The photodegradation of methyl orange (MO) under UV light by TiO₂/PVA spheres showed a good photocatalytic efficiency. Moreover, TiO₂/PVA spheres can be easily regenerated by the repeated immersion process. Overall, the porous TiO₂/PVA sphere displays a good photoactive property and an advantage of easier recovery, which facilitates its application in large-scale wastewater treatment.     

Effect of nano‐silica on the mechanical,thermal, and crystalline properties of poly(vinyl alcohol)/nano‐silica films

Poly(vinyl alcohol)/nano‐silica (PVA/nano‐SiO₂) films were prepared through extrusion blowing with the addition of water and glycerin as plasticizer. The characteristic properties of PVA/nano‐SiO₂ films were investigated by differential scanning calorimetry, dynamic mechanical analysis, Haake torque rheometry, and atomic force microscopy (AFM). The results showed that the mechanical properties of PVA/nano‐SiO₂ were improved dramatically. The tensile strength of the nanofilms increased from 62 MPa to 104 MPa with loading 0.3 wt % nano‐SiO₂ and the tear strength was improved from 222 KN/m to 580 KN/m. The crystallinity of the films loaded with 0.4 wt. % nano‐SiO₂ decreased from 32.2% to 21.0% and the AFM images indicated that the amorphous region of nanofilms increased with increasing nano‐SiO₂ content. The storage modulus and loss modulus increased to two and nearly three times with 0.3 wt % nano‐SiO₂ loading. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Electrospinning preparation and characterization of alumina nanofibers with high aspect ratio

Alumina nanofibers were successfully prepared via an electrospinning technique combined with a sol–gel method. The electrospinning solution was prepared by dissolving aluminum isopropoxide (AIP) in distilled water and then mixing with a polyvinyl alcohol (PVA) aqueous solution. The as-spun fibers were calcined at different temperatures and characterized by TG–DTA, XRD, SEM–EDS, TEM–SAED, and BET analysis. Results showed that the average fiber diameter decreases with increasing calcination temperature. The as-spun nanofibers were amorphous. After calcination at 1000 °C, the nanofibers formed were composed of α-Al₂O₃ and γ-Al₂O₃, showing an average diameter of 30–90 nm and an aspect ratio of greater than 1000. The pore size of the obtained fibers was approximately 5 nm, which implies that these fibers are mesoporous materials.     

聚乙烯醇/淀粉纳米晶复合膜的制备及表征

利用蜡质玉米淀粉通过硫酸酸解制备淀粉纳米晶（SN）,并采用溶液流延法制备聚乙烯醇（PVA）/SN复合膜,研究SN对复合膜结构和性能的影响。结果表明,制备的SN样品为盘状颗粒,平均直径为30～60 nm;随着SN含量的增加,PVA/SN复合膜的力学性能和阻隔性能均呈现先增后减的变化;在SN含量为10 %时,复合膜的拉伸和阻隔性能最好,拉伸强度由纯PVA膜的47 MPa提高至54 MPa,气体透过系数相对于纯PVA膜也降低了70 %。     

Effect of TiO2 nanoparticle on rheological behavior of poly(vinyl alcohol) solution

In recent years, addition of nanoparticles to fluids and polymers has been used as a way of modifying rheological properties. Poly(vinyl alcohol) (PVA) and titanium dioxide (TiO₂) nanoparticles aqueous composite nanofluids were prepared through the use of ultrasonic vibration. In fact, ultrasonic vibration is an advantageous method for nanoparticle dispersion. The preparation method prevents reduction of the polymer's molecular weight. TiO₂ nanoparticles with different concentrations were employed to investigate the rheological characteristics of composite nanofluids. Rheological characteristics of base fluids and composite nanofluids were measured at different temperatures. Based on the results, all composite nanofluids, as well as base fluids, exhibited non‐Newtonian behavior and rheological characteristics of composite nanofluids, following the Herschel‐Bulkley model. In addition, model parameters are functions of temperature, PVA, and TiO₂ nanoparticle concentrations. Also, two‐way interactions among temperature, PVA, and TiO₂ nanoparticle concentrations affect flow index and consistency index of the Herschel‐Bulkley model. J. VINYL ADDIT. TECHNOL., 23:234–240, 2017. © 2015 Society of Plastics Engineers     

Photocatalytic Deposition of Silver Nanoparticles onto Organic/Inorganic Composite Nanofibers

Summary: In this work, silver nanoparticles were embedded in electrospun organic/inorganic composite nanofibers consisting of PAN and TiO₂ through photocatalytic reduction of the silver ions in silver nitrate solutions under UV irradiation. The morphology and diameter of PAN/TiO₂ composite nanofibers could be controlled by varying the initial contents of TiO₂ in the spinning solution. From TEM images and UV‐Vis spectra, it has been confirmed that monodisperse silver nanoparticles with a diameter of ≈2 nm were deposited selectively upon the titania of the as prepared composite nanofibers. The amount of Ag nanoparticles embedded on composite nanofibers was greatly influenced by the amount of TiO₂ in composite nanofibers, reflecting the role of titania as the inorganic stabilizer and photocatalyst.

Morphology of silver nanoparticles embedded on PAN/TiO₂ composite nanofibers.     

Photoluminescent electrospun polymeric nanofibers incorporating germanium nanocrystals

The photoluminescent germanium nanocrystals (Ge-NCs) were successfully incorporated into electrospun polymeric nanofiber matrix in order to develop photoluminescent nanofibrous composite web. In the first step, the synthesis of Ge-NCs was achieved by nanosecond pulsed laser ablation of bulk germanium wafer immersed in organic liquid. The size, the structural and the chemical characteristics of Ge-NCs investigated by TEM, XPS, XRD and Raman spectroscopy revealed that the Ge-NCs were highly pure and highly crystalline having spherical shape within 3–20 nm particle size distribution. In the second step, Ge-NCs were mixed with polyvinyl alcohol (PVA) polymer solution, and then, Ge-NC/PVA nanofibers were obtained via electrospinning technique. The electrospinning of Ge-NCs/PVA nanoweb composite structure was successful and bead-free Ge-NCs/PVA nanofibers having average fiber diameter of 185 ± 40 nm were obtained. The STEM analysis of the electrospun Ge-NCs/PVA nanofibers elucidated that the Ge-NCs were distributed homogeneously in the polymeric nanofiber matrix. The UV–Vis absorption and photoluminescence spectroscopy studies indicated the quantum confinement effect of Ge-NCs on the optical properties of the electrospun Ge-NCs/PVA nanoweb.