Thin film composite nanofiltration membranes with polystyrene sodium sulfonate–polypiperazinetrimesamide semi-interpenetrating polymer network active layer

The present work depicts the preparation, characterization, and application of thin film composite nanofiltration (TFCNF) membranes. TFCNF membranes having polyacrylonitrile ultrafiltration support with active layer made of polystyrene sodium sulfonate–polypiperazinetrimesamide semi-interpenetrating polymer network (semi-IPN) are prepared. Membranes with semi-IPN active layer exhibited better hydrophilicity, higher negative zeta potential and surface roughness in comparison with NF membranes having virgin polypiperazinetrimesamide as the active layer. Semi-IPN membranes exhibited pure water permeability 103 ± 10 LMH at 150 psi pressure and rejection ratio of bivalent to monovalent salts as 2.7, whereas for virgin polypiperazinetrimesamide membrane the values, are 42 ± 5 LMH and 2.1, respectively. The semi-IPN NF membranes showed better antifouling behavior than the virgin polypiperazinetrimesamide membrane. The flux recovery ratio and total fouling ratio of semi-IPN NF membrane were observed 97.8 and 3.3% whereas for polypiperazinetrimesamide NF membranes, the values are 90.9 and 10.5%, respectively.     

Silver-doped titanium dioxide nanoparticles encapsulated in chitosan–PVA film for synergistic antimicrobial activity

The objective of the present study performed was to develop and characterize of silver (Ag)-doped titanium dioxide (TiO₂) naoparticles (NPs) encapsulated in chitosan–polyvinyl alcohol (PVA) film for synergistic antimicrobial activity. The acidic solution of chitosan with PVA was used for the reduction of silver ions into silver NPs using their functional groups such as hydroxyl, carboxyl, and amino groups. The chitosan–PVA silver nanoparticle films showed significant antimicrobial and antifungal activity against Staphylococcus aureus, Candida albicans, and Pseudomonas aeruginosa. Therefore, the present study is an alternative for conventional treatment as antimicrobial film showed synergistic, noninvasive, and economic effects.     

Bio-cellular glass–ceramic composite with embedded calcium phosphate from eggshell for alternative biomaterials in medical and dental applications

Green biomaterial foams with nontoxicity, low weight, low density, and high-compressive strength, which can be easily manufactured at low cost, are urgently sought. When implanted as a scaffold, bio-cellular glass–ceramic composite has potential for bone bonding, connective tissue growth, and reconstruction of lost tissue. The present study investigates the physical-thermo-mechanical properties of bio-cellular glass–ceramic composite supplemented with calcium phosphate from eggshell powder (0, 1, 3, or 5 wt%) and sodium-silicate binder. The composite materials were prepared by hand pressing and fired at 800 or 900°C for 1 h. The composites containing 1 and 3 wt% calcium phosphate from eggshell powder and fired at 800°C achieved suitable porosity (74–79%), pore size (20–800 μm), bulk density (0.57–0.70 g/cm³), true density (0.98–1.06 g/cm³), water absorption (10.31–21.41%), compressive strength (2.71–3.23 MPa), and thermal expansion coefficient ([5.95–5.98] × 10⁻⁶°C⁻¹) for practical applications. The obtained bio-cellular glass–ceramic composite is an alternative biomaterial for biomedical and dental applications.     

Electrospinning of polyvinylalcohol–polycaprolactone composite scaffolds for tissue engineering applications

Random nanofibrous composite scaffolds of PVA/PCL bilayer were fabricated by electrospinning method. The bilayer nanofibrous scaffolds were subjected to detailed structural, morphological, chemical, and thermal analysis using XRD, SEM, FTIR, and DSC. Morphological investigations revealed that the prepared nanofibers have uniform morphology and the average fiber diameters for bilayer samples A, B, and C are 203, 252, and 244 nm, respectively. The obtained scaffolds have a porous structure with porosity of 77, 89.2, and 78.3 % for bilayer samples A, B, and C, respectively. FTIR analysis ensured complete evaporation of solvent and formation of non-interactive bilayers. Biocompatibility of the membranes was investigated by studying the adhesion of mouse NIH 3T3 fibroblasts for 72 h, and its enhanced adhesion and proliferation proved its mettle as a potential scaffold for tissue engineering applications.     

Processing and characterization of elastomeric polycaprolactone triol–citrate coatings for biomedical applications

In this paper we describe the synthesis, processing and characterization of a novel elastic polyester coating created by carrying out catalyst-free polyesterification between biocompatible and non-toxic multifunctional reactants, namely polycaprolactone triol and citric acid. The physico-chemical and surface properties of the resulting polyester coatings and films have been investigated. This new material has been characterized by matrix-assisted laser desorption time-of-flight mass spectrometry (MALDI-ToF-MS), nuclear magnetic resonance spectroscopy (NMR), Fourier-transform infra-red spectroscopy (FTIR), water-in-air contact angle measurements, scanning electron microscopy (SEM), thermal analysis (DSC), mechanical tests and swelling experiments. The polymer structure, surface properties (morphology and chemistry), mechanical integrity and hydration of the elastomer can be controlled by simple variation of the initial citric acid concentration in the polymer formation. This feature of the novel polyester material presents a significant development in the production of advanced coatings for biomedical applications.     

Graphene oxide–polyoctahedral silsesquioxane–chitosan composite films with improved mechanical and water-vapor-transport properties

Graphene oxide (GO) and ball-milled maleamic acid–isobutyl polyoctahedral silsesquioxanes (MAIPSs) were incorporated simultaneously into chitosan (CS) via solution blending to evaluate their combined effects on the structures and properties of composite films. GO and MAIPS aggregates were homogeneously dispersed in CS and affected the crystallinities of the composite films. The binary addition of GO and MAIPS resulted in synergistic enhancements of the tensile strength and elongation at break of the composite films. Composite films containing 3% w/w MAIPS and 0.25% w/w GO (CS–GO–MAIPS-3) exhibited the highest strength and modulus, which were 48 and 42.2% higher, respectively, than the values of the CS film. The water-vapor-sorption isotherms revealed that monolayer sorption sites decreased with the addition of GO or/and MAIPS, but the dissolution process was not significantly influenced. The water-vapor permeability reached its lowest value for the CS–GO–MAIPS-3 film because of hindered diffusion with the presence of impermeable nanoparticles. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47748.     

Characterization of sol–gel coated 316L stainless steel for biomedical applications

Silica based organic–inorganic hybrid coatings were deposited on 316L stainless steel by sol–gel technique. The hybrid sols were prepared by hydrolysis and condensation of 3-methacryloxypropyltrimethoxysilane (TMSM) and tetraethylorthosilicate (TEOS) at different molar ratios. Electrochemical experiments were performed to evaluate the corrosion resistance properties of the coatings. Structural characterization of the coatings was performed using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. Contact angle measurement and cell morphology assay were performed to investigate the hydrophilicity and in vitro cytotoxicity of the coatings, respectively. The results indicate formation of a crack-free and highly adherent film acting as a protective barrier against the physiological medium. Corrosion resistance of hybrid coatings was influenced by the molar ratios of TMSM:TEOS. The best corrosion protection was obtained at TMSM:TEOS molar ratio of 1:1. Sol–gel coatings enhanced the hydrophilicity of 316L steel surfaces. Also, these coatings showed non-toxicity for L929 cells.     

Preparation and performance of PANI–PVA composite film doped with HCl

The polyaniline (PANI)–poly (vinyl alcohol) (PVA) composite film doped with HCl was prepared by adopting PVA as matrix. Effects of PVA content and film drying temperature on properties of HCl–PANI–PVA composite film were studied. A comparison was made for tensile strength, elasticity, conductivity and thermal stability of PVA, HCl–PANI or HCl–PANI–PVA. PVA film presented the highest tensile strength and elasticity (150.8?MPa and 300.0%), but its conductivity was the lowest. The conductivity of HCl–PANI–PVA was the highest (1500?S?m^?1), and tensile strength and elasticity of HCl–PANI–PVA were higher than those of HCl–PANI. The order of their thermal stability is PVA?>?HCl–PANI?>?HCl–PANI–PVA before 260°C, and the order of their thermal stability is HCl–PANI?>?HCl–PANI–PVA?>?PVA after 260°C. At the same time, the structure and conductive mechanism of composite materials were characterised and analysed through infrared and scanning electron microscopy (SEM).     

Adhesion evaluation of different bioceramic coatings on Mg–Ca alloys for biomedical applications

The aim of this study was to evaluate the adhesion of different bioceramic coatings deposited by radio frequency magnetron sputtering on the biodegradable implant-type magnesium–calcium (MgCa) alloys. Hydroxyapatite (HA) and bioactive glass (BG) were chosen as coating materials, due to their remarkable biological potential. The morphology, composition, structure and adhesion of the deposited thin coatings was characterized by scanning electron microscopy, atomic force microscopy, energy dispersive X-ray spectroscopy, grazing incidence X-ray diffraction, Fourier transform infrared spectroscopy and pull-out adherence measurements. A variation of the coating-to-substrate adhesion has been recorded and correlated with the physico-chemical results. The bonding strength values of the coatings were promising (being superior to the ISO13779-2:2008 fabrication standard for load-bearing biomedical coatings), and thus, encourage us to further proceed with the biological evaluation of the HA or BG coatings-MgCa substrate couples.     

A kinetic study of in situ polyaniline–gold composite film formation

Chloroaurate acid (HAuCl₄) was used as an oxidant and aniline (ANI) was used as a reducing agent to prepare a polyaniline–gold (PANI-Au) composite film by in situ polymerization. The formation of the composite film was monitored using a quartz crystal microbalance (QCM). The effects of the concentrations of HAuCl₄ and ANI as well as the reaction temperature on the formation of the PANI-Au composite film are discussed. The kinetics of the reaction were investigated by the QCM technique. The results indicate that the kinetics of the reaction are of order 0.5 with respect to HAuCl₄ and 1.5 with respect to aniline. The film growth rate increased with increasing ANI, HAuCl₄ concentration and reaction temperature. The activation energy calculated from the temperature dependence of the growth rate was 40.32 ± 0.15 kJ/mol. In situ UV-visible spectra of the reaction process were obtained and compared to the reaction process using the QCM technique.     

Physical modification of polymeric support layer for thin film composite forward osmosis membranes by metal–organic framework-based porous matrix membrane strategy

Physical modification of support layers (SLs) for thin-film composite (TFC) forward osmosis (FO) membranes is the main goal of this study. Accordingly, the strategy of metal–organic framework (MOF)-based porous matrix membrane (PMM) was used for the fabrication of controllable SLs. Fourteen different TFC FO membranes were successfully fabricated by interfacial polymerization (IP) technique over the fourteen different SLs made of polyetherimide (PEI), polyethersulfone (PES), and twelve MOF-based PMM. The controllable MOF particles, fabricated SLs, and TFC membranes were characterized by Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (PXRD), dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), contact angle (CA), inductively coupled plasma (ICP), and developed SHN1 method. The results showed that the PMM strategy can lead to an increase in the degree of crosslinking of polyamide (PA) as a result of physical modification of the original SLs. Also, the PMM strategy reduced the structural parameters and hence the internal concentration polarization (ICP) was controlled. However, according to the characteristic curve, physical modification of the structure of PES and PEI by MOF-based PMM strategy caused a small and dramatic effect (respectively) on the performance of the TFC FO membranes. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 137, 48672.     

Ag/Ag2S–TiO2 composite film formed using dual phase Ag/Ag2O layer as a sulfurized layer for enhanced photocatalytic activity

The Ag/Ag₂S–TiO₂ composite films were synthesized through vulcanizing sputtering Ag/Ag₂O dural-phase template capping layer on the TiO₂ film. After hydrothermal vulcanization using thiourea as a sulfur precursor, the initially decorated Ag₂O layer transformed into the Ag₂S. The surface morphology of the continuous block structure of the Ag/Ag₂S composite layer gradually shrinks to form irregular island grains dispersed on the surface of the composite film, with vulcanization reaction duration increased from one to 3 h. The light absorption ability of the Ag/Ag₂S–TiO₂ composite film was enhanced substantially compared to the TiO₂ film because of the surface plasmon resonance effect from the Ag particles and the narrow energy band of the Ag₂S. Among various surface morphologies of the Ag/Ag₂S–TiO₂ composite films, the irregular island Ag/Ag₂S grains-decorated TiO₂ composite film presents superior photoelectrochemical and photocatalytic degradation performances than the composite films consisting of continuous block and spider-web structure of the Ag/Ag₂S decorated layers. The synergistic effects of surface plasmon resonance, Ag pathway between the semiconductors, and Z-scheme charge transfer mechanism explain the high-efficiency photocatalytic activity of the Ag/Ag₂S–TiO₂ composite films.     

Preparation of erythritol–graphite foam phase change composite with enhanced thermal conductivity for thermal energy storage applications

Three-dimensional interconnected graphite composite foam as a heat conductive matrix was fabricated by using low cost polymeric precursors and polyurethane (PU) foam as carbon source and sacrificial macroporous template, respectively. Erythritol–graphite foam as a stable composite phase change material (PCM) was obtained by incipient wetness impregnation method. The thermophysical properties such as thermal diffusivity, specific heat, thermal conductivity and latent heat of the erythritol–graphite composite foam were measured. From the results, it was found that the thermal conductivity of the erythritol–graphite composite foam (3.77 W/mK) was enhanced 5 times as compared with that of pristine erythritol (0.72 W/mK). This enhancement can significantly reduce the charging and discharging times of the PCM storage system. There is no chemical reaction between erythritol and graphite as confirmed by X-ray diffractometer (XRD). The PCM/foam composite has a melting point of 118 °C and latent heat of 251 J/g which corresponds to the mass percentage (75 wt.%) of the erythritol within the composite foam. The obtained results confirmed the feasibility of using erythritol–graphite foam as a new phase change composite for thermal energy storage (TES) applications, thus it can contribute to the efficient utilization and recovery of solar heat or industrial waste heat.     

Preparation of PANI–PVA composite film with good conductivity and strong mechanical property

The polyaniline (PANI)–polyvinyl alcohol (PVA) conductive composite films [doped with hydrochloride (HCl), dodecylbenzene sulphonic acid and amino sulphonic acid (NH₂SO₃H) aqueous solution] were synthesised by ‘in situ’ polymerisation, and their conductivities were compared. Among these composite films, HCl–PANI–PVA composite film possessed the highest conductivity that reached 1360?S·m^??1 [w_(PVA)?=?40%]. Meanwhile, the effects of PVA content, HCl concentration, oxidant ammonium persulphate (APS) dosage, reaction time and film drying temperature on tensile strength of the HCl–PANI–PVA composite films were studied. The tensile strength of the film was improved greatly due to effective mixture of PANI and PVA. When the PVA content was 40%, C_(HCl)?=?1.0?mol·L^??1, reaction time was 4.0?h, n_(APS)/n_(aniline)?=?1.0 and film drying temperature was 80°C, and the tensile strength of the HCl–PANI–PVA composite film reached the maximum of 60.8?MPa. At the same time, the structure of composite materials was characterised and analysed through ultraviolet spectrum and SEM.     

Diamond–carbon nanocomposites: applications for diamond film deposition and field electron emission

Diamond–carbon nanocomposites (DCN) containing diamond and graphitic particles, both a few nanometers in size, were studied as the material for field electron emission. Diamond–carbon mass ratio and grain size were varied to optimize field emission properties. The stable and uniform electron emission was observed at fields E=10 V μm⁻¹ with a negligible hysteresis of I–V curves. Treatment in microwave hydrogen plasma was found to reduce the threshold field for emission owing to preferential etching of carbon component and surface relief sharpening. Ultrathin chemical vapour deposition diamond films can be easily grown on DCN due to the very high nucleation density inherent to this composite.     

Correlating the microstructure of Mn–Zn ferrite with magnetic noise for magnetic shield applications

Many sensitive atomic devices require magnetic shield to reduce external magnetic field interference. Mn–Zn ferrites are optimistic candidates for shielding because they provide a high shielding factor and a low magnetic noise. This study evaluated the magnetic noise of Mn–Zn ferrite magnetic shield based on its grain size. The morphologies of Mn–Zn ferrite samples were characterized to establish a correlation between their grain sizes and magnetic permeability, which can be used to calculate magnetic noises. The correlation was then used to evaluate the shielding performance of another Mn–Zn ferrite, where the magnetic noise of the magnetic shield made from the ferrite was calculated to be 2.53 f ^−1/2fT. The magnetic noise of the magnetic shield was also measured experimentally using a spin-exchange relaxation-free atomic magnetometer. The measured magnetic noise of ferrite shield was 2.61 f ^−1/2fT, while the white noise of the atomic magnetometer was 0.71 fT/Hz^1/2 below 100 Hz. The consistency between the experimental results and predicted values suggests the viability of the proposed approach, providing a convenient, efficient, and precise method for developing ferrite ceramics materials for low-noise magnetic shields.     

Transparent Al–In–Zn–O Oxide semiconducting films with various in composition for thin-film transistor applications

Al–In–Zn–O thin-film transistors were fabricated. To examine the effect of In composition, we adopted a co-sputtering method using Al–Zn–O and In₂O₃ targets. The sputtering power of In₂O₃ was varied to 200, 150, and 50 W. The mobility and turn-on voltage of each device were 27.8 cm²V⁻¹ s⁻¹ and −4.2 V, 4.5 cm²V⁻¹ s⁻¹ and −3.5 V, 0.7 cm²V⁻¹ s⁻¹ and −3 V, respectively. We also investigated instabilities under negative gate bias stress (NBS) and negative bias illumination stress (NBIS). While the NBS was not influenced by the In contents, the NBIS characteristics were optimized for the device with In₂O₃ sputtering at 150 W.     

A solution strategy for the film model for non-isothermal gas–liquid reactions

A general solution strategy for the film model for gas–liquid reaction has been proposed using the boundary element method (BEM) of discretization over subintervals in gas–liquid films. Non-isothermal effects in the film are included and the associated temperature changes near the gas–liquid interface are computed. The accuracy of the solution procedure is first established using some simple isothermal and non-isothermal benchmark problems and with semi-analytical solutions. Then illustrative results are presented for a non-isothermal series reaction system to illustrate effects of various parameters such as Arrhenius number, solubility changes with temperature, effect of volatility of the liquid phase reactant, etc. The proposed solution method provides fast and accurate values for interfacial fluxes and fluxes into the bulk liquid in addition to concentration profiles. Hence the method is extremely useful for coupling local effects of the film model with global effects based on CFD coupled compartmental model for gas–liquid reactors.