Solvent Bath Research Articles

Preparation and antifouling property improvement of Tröger's base polymer ultrafiltration membrane

Tröger's base (TB) polymers have received increasing interest for different potential applications in the field of membrane techniques. In this study, a TB polymer was used for the first time to prepare ultrafiltration (UF) membrane and its antifouling property was enhanced through membrane quaternization process. The pure water flux of TB UF membrane prepared from NMP solution was 448 L m−2 h−1 with a high rejection for solute (97% for bovine serum albumin (BSA) and 90% for humica acid). The high permeability of TB UF membrane was related to its high overall porosity, while the high separation property was attributed to its small average pore size on the surface as evidenced by SEM observations. Due to the presence of tertiary amine groups, the TB membrane was further functionalized by the quaternization with methyl iodide. Surprisingly, the antifouling property of quaternized TB (QTB)membrane was improved when using BSA as a model foulant when compared to the TB membrane. The flux recovery ratio of QTB membrane was enhanced from 55% to 91% when the quaternization degree was 10%. This may be attributed to the enhanced hydrophilicity of membrane surface after the quaternization of tertiary amino groups. More importantly,QTB membrane showed higher pure water flux, BSA solution flux and flux recovery ratio than the commercial PAN, PES, PSf and PVDF membranes through a three-cycle of membrane fouling test. Moreover, the effect of polymer concentration in the casting solution, type of solvent and coagulation bath temperature on the UF membrane morphology and ultrafiltration performance were investigated.

Transient instabilities in the swelling dynamics of a hydrogel sphere

We investigate the swelling dynamics driven by solvent absorption in a hydrogel sphere immersed in a solvent bath, through a computational model and a numerical study. We extensively describe the transient process from dry to wet and discuss the onset of surface instabilities through a measure of the lack of smoothness of the outer surface and a morphological pattern of that surface with respect to the two material paremeters driving the swelling dynamics.

Chemically Stable Atomic-Layer-Deposited Al2O3 Films for Processability.

Atomic-layer-deposited alumina (ALD Al2O3) can be utilized for passivation, structural, and functional purposes in electronics. In all cases, the deposited film is usually expected to maintain chemical stability over the lifetime of the device or during processing. However, as-deposited ALD Al2O3 is typically amorphous with poor resistance to chemical attack by aggressive solutions employed in electronics manufacturing. Therefore, such films may not be suitable for further processing as solvent treatments could weaken the protective barrier properties of the film or dissolved material could contaminate the solvent baths, which can cause cross-contamination of a production line used to manufacture different products. On the contrary, heat-treated, crystalline ALD Al2O3 has shown resistance to deterioration in solutions, such as standard clean (SC) 1 and 2. In this study, ALD Al2O3 was deposited from four different precursor combinations and subsequently annealed either at 600, 800, or 1000 °C for 1 h. Crystalline Al2O3 was achieved after the 800 and 1000 °C heat treatments. The crystalline films showed apparent stability in SC-1 and HF solutions. However, ellipsometry and electron microscopy showed that a prolonged exposure (60 min) to SC-1 and HF had induced a decrease in the refractive index and nanocracks in the films annealed at 800 °C. The degradation mechanism of the unstable crystalline film and the microstructure of the film, fully stable in SC-1 and with minor reaction with HF, were studied with transmission electron microscopy. Although both crystallized films had the same alumina transition phase, the film annealed at 800 °C in N2, with a less developed microstructure such as embedded amorphous regions and an uneven interfacial reaction layer, deteriorates at the amorphous regions and at the substrate–film interface. On the contrary, the stable film annealed at 1000 °C in N2 had considerably less embedded amorphous regions and a uniform Al–O–Si interfacial layer.

Smelting of Industrial Solid Waste for Recovery of Aluminum: Effect of Charge Material

The present paper deals with the effect of charge material on the recovery of aluminum from the industrial solid waste. For the efficient recovery of aluminum metal having a lower vaporization temperature, smelting was carried out in the presence of metal (iron) solvent bath inside a graphite crucible. Nitrogen plasma arc was generated by passing the current as well as the nitrogen gas through a hollow graphite electrode. Charge containing bottom ash or a mixture of iron ore slime and bottom ash along with a reductant of different reactivity was used either in the form of powder or pellets. Liquid iron bath below the plasma arc zone was utilized as a solvent for the absorption of reduced metals after reduction of the oxides present in the wastes. The quick absorption of aluminum in the liquid iron bath subsequent to the reduction of oxides under an inert atmosphere minimized the vaporization loss of aluminum. The effects of carbon content and its reactivity, form of charge material, charge-layer thicknesses for different charge compositions on the recovery of aluminum were studied for 30 min of plasma exposure times in all cases. Maximum recovery of aluminum was found for the charge in powder form having a mixture of bottom ash and iron ore slime along with the increased carbon content as well as charge-layer thickness, respectively. The recovery of aluminum was found to be up to 40.80% for the powder charge containing 50% bottom ash and 50% iron ore slime with the char in double stoichiometry carbon.

Color optimization of red organic light emitting diodes (OLEDs) through dihydroxyphenyl-substituted zinc porphyrins emitters

Abstract Four tetrakis (dihydroxyphenyl) Zinc(II) porphyrin (Zn-TDHPP) were successfully synthesized and used as fluorescent materials in organic light-emitting diodes (OLEDs). Devices were fabricated with an indium tin oxide(ITO)/poly (3,4-ethylenedi-oxythiophene):poly (styrenesulfonate) (PEDOT:PSS) (55 nm)/polyvinylcarbazole (PVK):(2-(4-biphenyl)-5-(4-t-butylphenyl)1,3,4-oxadiazole) (PBD):Zn-TDHPP derivatives (80 nm)/Al (150 nm). The resultant devices had peak emissions ranging from 602 nm to 645 nm. It has been shown that with modification of Zn-TDHPP molecule having specific backbone with different functional groups R (R OH, COOH), we could change and control its optical properties such as band gap energy, photoluminescence (PL) and electroluminescence (EL) spectra along with its electrical properties such as current diagram of OLED devices. In addition, it is possible to modify Commission Internationale de l’Eclairage (CIE) coordinates of EL spectrum of fabricated OLED devices for application in the display industry. We used dichloromethane bath and Ultra-Violet laser (405 nm) for improvement of the morphology of layers. Atomic force microscopy (AFM) measurement showed that the morphology of the layers depends on the type of laser irradiations and solvent bath.

A research on CO2 removal via hollow fiber membrane contactor: The effect of heat treatment

The aim of this work was to investigate the effects of heat treatment applying hot air at different temperatures and durations on the morphology and the performance of polyetherimide (PEI) hollow fiber membrane contactors for CO2 separation. The membranes were fabricated via a wet spinning into non solvent bath technique. Then, the membranes were heat treated by exposing them at 80,120 and 160°C for all time intervals of 5, 15 and 30min under a hot air atmosphere. To study the influence of the hot air on the membranes structural parameters and the performance of the membranes they were characterized by: gas permeation test, membrane overall porosity measurement, critical entry pressure of water (CEPw) and gas absorption via a membrane contacting process. The experimental results revealed that, the greatest effect on the membranes structure was observed in the shortest time duration and the lowest temperature i.e. 5min and 80°C, which exhibited a pore size of 49 (nm), a maximum effective surface porosity of 26.8 (1/m) and a CEPw of 3.4bar. Also, for all the time periods and the temperatures tested, the density of the fibers reduced and the CEPws along with the overall porosities increased. In conclusion, applying heat treatment technique on PEI hollow fiber membranes is a simple and easy approach to improve the performance of hollow fiber membrane contactors for CO2 removal.

The improved breathability of polyurethane coated cotton fabric via micro-cracking

Polyurethane (PU) coating became popular in the last decades to achieve water resistance garment fabrics with enhanced visual properties. But reduced breathability of coated fabric is a setback for clothing industry. This paper represents a facile method of enhancing breathability (air and water vapor permeability) of PU coated fabrics which may be so-called micro-cracking in relevant solvent bath differed in solvent bath, concentration, and duration time. The samples were subjected to air permeability, water vapor permeability, water resistance, and tensile strength measurements and the results were also statistically analyzed. The study showed that the proposed process increased water vapor and air permeability of coated but the permeability values were still significantly lower than that of uncoated sample. This result is also verified through water resistance measurements and; tensile strength of the samples were affected at minimum after micro-cracking.

Ultrafast photophysical studies of a multicomponent sunscreen: Oxybenzone–titanium dioxide mixtures

Recent studies of the sunscreen constituent oxybenzone have suggested that the dominant mechanism underlying the efficient photoprotection it offers relies on an initial ultrafast enol→keto tautomerisation, followed by nonadiabatic transfer to the ground electronic state. Subsequent collisions with the solvent bath then reform the original enol-tautomer. Utilising femtosecond transient electronic absorption spectroscopy we explore the dissipation of electronic excitation energy in oxybenzone in the presence of titanium dioxide, a widely used, and complementary sunscreen component. We find the relaxation dynamics of this popular organic filter are unaltered by the presence of this favoured inorganic scatterer and the overall dynamics can be described by the additive contribution of the individual constituents. The combination of the two components provides broadband photoprotective properties justifying the widely used organic filter and inorganic scatterer mixtures in commercial sunscreen products.

Comparison of different coupling schemes between counterions and charged nanoparticles in multiparticle collision dynamics.

We applied the multiparticle collision dynamics (MPC) simulation technique to highly asymmetric electrolytes in solution, i.e., charged nanoparticles and their counterions in a solvent. These systems belong to a domain of solute size which ranges between the electrolyte and the colloidal domains, where most analytical theories are expected to fail, and efficient simulation techniques are still missing. MPC is a mesoscopic simulation method which mimics hydrodynamics properties of a fluid, includes thermal fluctuations, and can be coupled to a molecular dynamics of solutes. We took advantage of the size asymmetry between nanoparticles and counterions to treat the coupling between solutes and the solvent bath within the MPC method. Counterions were coupled to the solvent bath during the collision step and nanoparticles either through a direct interaction force or with stochastic rotation rules which mimic stick boundary conditions. Moreover, we adapted the simulation procedure to address the issue of the strong electrostatic interactions between solutes of opposite charges. We show that the short-ranged repulsion between counterions and nanoparticles can be modeled by stochastic reflection rules. This simulation scheme is very efficient from a computational point of view. We have also computed the transport coefficients for various densities. The diffusion of counterions was found in one case to increase slightly with the volume fraction of nanoparticles. The deviation of the electric conductivity from the ideal behavior (solutes at infinite dilution without any direct interactions) is found to be strong.

Polyamide/polyacrylonitrile thin film composites as forward osmosis membranes

ABSTRACTThin film composites (TFCs) as forward osmosis (FO) membranes for seawater desalination application were prepared. For this purpose, polyacrylonitrile (PAN) as a moderately hydrophilic polymer was used to fabricate support membranes via nonsolvent‐induced phase inversion. A selective thin polyamide (PA) film was then formed on the top of PAN membranes via interfacial polymerization reaction of m‐phenylenediamine and trimesoyl chloride (TMC). The effects of PAN solution concentration, solvent mixture, and coagulation bath temperature on the morphology, water permeability, and FO performance of the membranes and composites were studied. Support membranes based on low PAN concentrations (7 wt %), NMP as solvent and low coagulation bath temperature (0 °C) demonstrated lower thickness, thinner skin layer, more porosity, and higher water permeability. Meanwhile, decreasing the PAN solution concentration lead to higher water permeance and flux and lower reverse salt flux, structural parameter, and tortuosity for the final TFCs. Composites made in N,N‐dimethylformamide presented lower permeance and flux for water and salt and higher salt rejection, structural parameter, and tortuosity. FO assay of the composites showed lower water permeance values in saline medium comparing to pure water. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44130.

A highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) film with the solvent bath treatment by dimethyl sulfoxide as cathode for polymer tantalum capacitor

The highly conductive poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) films were prepared on porous tantalum pentoxide surface as cathode for polymer tantalum capacitors (PTC). The electrical performances of PTC with PEDOT:PSS films as cathode were optimized by dimethyl sulfoxide (DMSO) bath treatment. With the DMSO-bath treatment of PTC, the equivalent series resistance (ESR) of PTC decreased from 25mΩ to 9mΩ. The ultralow ESR led to better capacitance-frequency performance. The device reliability investigation revealed the enhanced environmental stability of PTC. The enhanced performances were attributed to the conductivity improvement of PEDOT:PSS cathode films and the removal of excess PSS from PEDOT:PSS films.

Finite bending solutions for layered gel beams

We investigate the swelling–induced bending of a gel bilayer beam with homogeneous beam–like components, when the beam is embedded in a solvent bath of assigned chemical potential. We set the problem within the limits of finite elasticity with large distortions, with these latter determined via chemical equilibrium, by the elastic modulus of the gel, the chemical potential of the bath and the solvent–gel interaction parameter. We borrow our method of solution from finite bending of soft and incompressible beams, and get a non dimensional nonlinear equation governing the solution of the problem, whose solution is validated through a campaign of numerical experiments based on a complete stress–diffusion model.

Dynamics of bimolecular reactions in solution.

Mechanisms of bimolecular chemical reactions in solution are amenable to study on picosecond timescales, both by transient absorption spectroscopy and by computer simulation. The dynamics of exothermic reactions of CN radicals and of Cl and F atoms with organic solutes in commonly used solvents are contrasted with the corresponding dynamics in the gas phase. Many characteristics of the gas-phase reaction dynamics persist in solution, such as efficient energy release to specific vibrational modes of the products. However, additional complexities associated with the presence of the solvent are open to investigation. These features of liquid-phase reactions include the role of solvent-solute complexes, solvent caging, coupling of the product motions to the solvent bath, thermalization of internally excited reaction products, incipient hydrogen bond formation, and involvement of charge-separated states that arise from proton transfer.

Swelling-induced and controlled curving in layered gel beams.

We describe swelling-driven curving in originally straight and non-homogeneous beams. We present and verify a structural model of swollen beams, based on a new point of view adopted to describe swelling-induced deformation processes in bilayered gel beams, that is based on the split of the swelling-induced deformation of the beam at equilibrium into two components, both depending on the elastic properties of the gel. The method allows us to: (i)determine beam stretching and curving, once assigned the characteristics of the solvent bath and of the non-homogeneous beam, and (ii) estimate the characteristics of non-homogeneous flat gel beams in such a way as to obtain, under free-swelling conditions, three-dimensional shapes. The study was pursued by means of analytical, semi-analytical and numerical tools; excellent agreement of the outcomes of the different techniques was found, thus confirming the strength of the method.

Characterization of the microstructure of GaP films grown on {111} Si by liquid phase epitaxy.

The development of a cost-effective Si based platform on which III-V's can be grown is of great interest. This work investigates the morphology of gallium phosphide (GaP) films grown on {111} silicon (Si) substrates by means of liquid phase epitaxy in a tin (Sn) - based solvent bath. Two types of single-crystal {111} Si substrates were used; the first type was oriented exactly along the ⟨111⟩ surface (no-miscut) and the second was miscut by 4°. The growth rate of the GaP films was found to be markedly different for the two types of substrates; the GaP films on the miscut Si substrate grew ∼4 times faster than those on the no-miscut substrate. The GaP films grew epitaxially on both types of substrates, but contained Si and Sn as inclusions. In the case of the no-miscut substrate, a number of large Sn particles were incorporated at the GaP/Si interface. As a result, these interfacial Sn particles affected the strain state of the GaP films dramatically, which, in turn, manifested itself in the form of a duplex microstructure that consists of strained and strain-free regions.

Effects of different solvent baths on the performances of dye-sensitized solar cells: Experimental and theoretical investigation

Combining experimental analyses and computational modeling, we investigated CD-7-sensitized solar cells (DSSCs) by THF or DMF bath with aim to understand the effects of different solvent baths on the performances of the corresponding DSSCs. In experiment, the photophysical, photovoltaic and electrochemical impedance properties of the DSSCs based on THF or DMF bath were investigated. The UV–vis spectrum of CD-7 in THF is red-shifted in comparison with it in DMF, indicating that there are different interactions between CD-7 and the solvent molecules. The UV–vis spectrum of CD-7 adsorbed on TiO2 film suggested that different solvent baths have different effects on the J-aggregation and absorption strength. Monochromatic incident photon-to-electron conversion efficiency (IPCE) and electrochemical impedance analyses showed that different solvent baths have significant influences on the IPCE values and electron lifetimes of the corresponding DSSCs. The analysis results of computational modeling showed that the solvent molecules would affect the energy level of TiO2, adsorption structure and adsorbed amount of CD-7 on the TiO2 film. The above analysis results illuminate a big difference in the performances of DSSCs by THF or DMF bath. The DSSCs based on THF bath obtained the η value 1.53%, which is about twice as much as that of DMF bath.

The Influence of Cholesterol on Fast Dynamics Inside of Vesicle and Planar Phospholipid Bilayers Measured with 2D IR Spectroscopy.

Phospholipid bilayers are frequently used as models for cell membranes. Here the influence of cholesterol on the structural dynamics in the interior of 1,2-dilauroyl-sn-glycero-3-phosphocholine (dilauroylphosphatidylcholine, DLPC) vesicles and DLPC planar bilayers are investigated as a function of cholesterol concentration. 2D IR vibrational echo spectroscopy was performed on the antisymmetric CO stretch of the vibrational probe molecule tungsten hexacarbonyl, which is located in the interior alkyl regions of the bilayers. The 2D IR experiments measure spectral diffusion, which is caused by the structural fluctuations of the bilayers. The 2D IR measurements show that the bilayer interior alkyl region dynamics occur on time scales ranging from a few picoseconds to many tens of picoseconds. These are the time scales of the bilayers' structural dynamics, which act as the dynamic solvent bath for chemical processes of membrane biomolecules. The results suggest that at least a significant fraction of the dynamics arise from density fluctuations. Samples are studied in which the cholesterol concentration is varied from 0% to 40% in both the vesicles (72 nm diameter) and fully hydrated planar bilayers in the form of aligned multibilayers. At all cholesterol concentrations, the structural dynamics are faster in the curved vesicle bilayers than in the planar bilayers. As the cholesterol concentration is increased, at a certain concentration there is a sudden change in the dynamics, that is, the dynamics abruptly slow down. However, this change occurs at a lower concentration in the vesicles (between 10% and 15% cholesterol) than in the planar bilayers (between 25% and 30% cholesterol). The sudden change in the dynamics, in addition to other IR observables, indicates a structural transition. However, the results show that the cholesterol concentration at which the transition occurs is influenced by the curvature of the bilayers.

Electrodeposition of Aluminum from 1,3-Dimethyl-2-Imidazolidinone/AlCl3 baths

This study investigated the use of novel organic solvent baths for the electrodeposition of aluminum at near-ambient temperatures. It was found that Al metal can be electrodeposited from baths that were composed of 1,3-dimethyl-2-imidazolidinone (DMI) and AlCl3, with an AlCl3 concentration greater than 50 mol%. IR spectroscopy indicated that Al2Cl7− ions were present in the baths that contained >50 mol% AlCl3, where the electrodeposition of Al occurs from Al2Cl7− ion. The DMI/AlCl3 baths with AlCl3 concentrations between 59 and 64 mol% retained a single liquid phase without precipitation at 25°C, and therefore, they can be used for Al electrodeposition near room temperature. Smooth Al films could be obtained by galvanostatic electrodeposition at 40°C using a DMI/AlCl3 bath with the addition of a trace amount of 1,10-phenanthroline.

Alumina nanostructured coating for corrosion protection of 316L stainless steel

Nanostructured alumina thin films were coated on stainless steel by Sol-Gel dip coating method. In order to prevent crack formation, Al2O3 films were kept in a solvent bath immediately after coating to reduce the rate of drying. Effects of calcination temperature and withdrawal speed on structural properties were analyzed using XRD and SEM. Topography and thickness of coatings were analyzed by AFM. Effects of the above parameters on anticorrosion performance of coats have been evaluated through electrochemical polarization technique. The results indicated that the optimum calcination temperature to achieve the best corrosion protection was 400oC. The thickness of one time coating with 1mm/s withdrawal speed was about 146 nm.

Size-dependent ultrafast structural dynamics inside phospholipid vesicle bilayers measured with 2D IR vibrational echoes

The ultrafast structural dynamics inside the bilayers of dilauroylphosphatidylcholine (DLPC) and dipalmitoylphosphatidylcholine vesicles with 70, 90, and 125 nm diameters were directly measured with 2D IR vibrational echo spectroscopy. The antisymmetric CO stretch of tungsten hexacarbonyl was used as a vibrational probe and provided information on spectral diffusion (structural dynamics) in the alkyl region of the bilayers. Although the CO stretch absorption spectra remain the same, the interior structural dynamics become faster as the size of the vesicles decrease, with the size dependence greater for dipalmitoylphosphatidylcholine than for DLPC. As DLPC vesicles become larger, the interior dynamics approach those of the planar bilayer.