Bio‐inspired synthesis of molecularly imprinted nanocomposite membrane for selective recognition and separation of artemisinin

Inspired from the highly bioadhesive performance of mussel protein, a simple, yet efficient synthetic method for efficiently imprinting of Artemisinin (Ars) was developed to prepare the bio‐inspired molecularly imprinted membranes (MIMs) via atom transfer radical polymerization (ATRP). In this work, attributed to the unique properties of polydopamine (pDA) modified layers and ATRP technology, the uniform recognition sites for efficiently selective extraction of the Ars with high stability could be obtained on the MIMs surfaces. In addition, the maximum adsorption capacity of the MIMs is 158.85 mg g^?1 by the Langmuir isotherm model, which is remarkable higher than NIMs. Additionally, because of the formation of the uniform specific recognition cavities on membrane surfaces, the as‐prepared MIMs exhibited a rapid adsorption dynamics and well‐fitted for the pseudo‐second‐order rate equation, also, possessed an excellent per‐selectivity performance (β_{artemether/Ars} values is 0.18) of template molecule, which clearly demonstrated the potential value of this method in the selective separation and purification of Ars. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43405.     

Fabrication of dual-layer poly(styrene-b-4-vinyl pyridine)–poly(vinylidene fluoride) membranes with tailored pore sizes under 10 nm via surface quaternization

Block copolymer membranes can be applied to precise size-based separation because of their highly ordered surface morphology and adjustable pore sizes. However, there is a lower limit of the scale of block copolymer self-assembly; this makes it a challenge to tailor the pore size down to below 10 nm. In this study, poly(styrene-b-4-vinyl pyridine) membranes were modified to quaternized selective layers with pores smaller than 10 nm and were supported by poly(vinylidene fluoride) hollow fibers as the substrate to provide a high mechanical strength. Two reactants, methyl iodide and 2-chloroacetamide, were used in the quaternization. With this one-step chemical modification, the molecular weight cutoff was reduced from 190 to 8 kDa, and the surface pore sizes were narrowed down from 20–30 to 3 nm; this bridged the gap of tailored pore sizes down to below 10 nm. Such membranes are promising candidates for low-molecular-weight separation with high resolution. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47137.     

Octadecyl‐silica—PVDF membrane of superior MD desalination performance

Despite its widespread industrial and residential uses for production of potable water, the reverse osmosis (RO) desalination process has some drawbacks by discharging harmful concentrated saline water as reject stream. A hydrophobic porous membrane can treat such environmentally unfriendly RO reject stream via Membrane Distillation (MD) process. Here, we describe preparation of superior polyvinylidenefluoride (PVDF) membrane modified with superhydrophobic silica nanoparticles for desalination application. Superhydrophobicity (contact angle of 151°) of silica nanoparticles of 7 nm sizes was achieved by reaction of the silica particles with octadecyltrichlorosilane in toluene to form ? Si? O? Si? links with C18 alkyl chain. A homogeneous polymer dope mixture containing a desired amount of modified silica colloids suspended in toluene was used for the membrane preparation. The PVDF membrane with optimal silica content exhibited excellent flux with >99% salt rejection efficiency when used for MD at room temperature from the saline water feed of 3.5 wt % NaCl. The prepared hydrophobic PVDF membrane has the potential for MD application in treating the RO reject stream and other aqueous industrial effluents. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46043.     

Adsorption of platinum(IV) from an aqueous solution with magnetic cellulose functionalized with thiol and amine as a nano‐active adsorbent

In this study, magnetic cellulose was prepared and then functionalized by the grafting of glycidyl methacrylate and reaction with thiourea/amine [to produce grafted magnetic cellulose with thiol/amine (GMC–N/S)]. Thus, GMC–N/S as a nano‐active adsorbent was investigated for the adsorption of Pt(IV) in a batch system. A response surface methodology was used to study the effects of four independent variables [Pt(IV) concentration, temperature, pH of the solution, and adsorbent dose] and to optimize the process conditions for the maximum adsorption of platinum(IV) from aqueous solutions by GMC–N/S. A high coefficient of determination (R² = 98.46) implied the adsorption of Pt(IV) onto the adsorbent in a valid manner, and only 1.54% of the total variable was not explained by the model. The equilibrium adsorption data were fitted to the Langmuir isotherm. The maximum monolayer adsorption capacity of the adsorbent (GMC–N/S) for Pt(IV) was determined to be 40.48 mg/g. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45361.     

Cyclodextrin‐dendrimer functionalized polysulfone membrane for the removal of humic acid in water

Commercial polysulfone (PSf) membranes were crosslinked with a β‐cyclodextrin‐poly (propyleneimine) (β‐CD‐PPI) conjugate which had β‐CD pendant arms using trimesoyl chloride (TMC) by interfacial polymerization. The morphology and physicochemical properties of the nanofiltration membranes were characterized using Fourier transform infrared/attenuated total reflectance (FT‐IR/ATR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and cross‐flow filtration system. Water‐contact angle, water‐intake capacity, and rejection capacities of the membranes were evaluated. The β‐CD‐G4 (generation 4)‐PPI‐PSf and β‐CD‐G3 (generation 3)‐PPI‐PSf membranes both exhibited high humic acid rejection of 72% as compared to the commercial PSf which exhibited 57%. The modified membranes were also more hydrophilic (36° to 41°) than PSf (76°). These results suggest that β‐CD‐PPI nanostructures are promising materials for the synthesis of membranes for the removal of humic acid from water. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4428–4439, 2013     

Enhancement of the hydrophobicity of recycled polystyrene films using a spin coating unit

This article describes a technique for recycling polystyrene cups (PS_r) mixed with poly(butyl methacrylate) (PBMA) to produce PS_r/PBMA films and subsequently PS_r films by removing PBMA with a selective solvent (acetic acid), with the benefit of a reduction in environmental pollution generated by polystyrene waste. Removal of PBMA increases roughness, which generates a significant increase ( 34°) in the water contact angle, reaching its highest value at 128°. By increasing the hydrophobicity of surfaces, properties with important technical applications are acquired such as those used in antifouling paints, stain‐resistant surfaces, and surfaces that avoid the formation and accretion of ice on microelectronic devices. Roughness of PS_r/PBMA films is significantly affected by the concentration of both polymers and by the spin rate, reaching its highest value at 2% PS_r and 3% PBMA at 2000 . For optimal film deposition, a cheap spin coating unit was designed and built, with a price less than 4% of that of a commercially available spin coating unit. Lastly, it was found that the data obtained with our spin coating unit is described by the Meyerhofer model with accuracy of 88% ± 3%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45365.     

Breath figure templated semifluorinated block copolymers with tunable surface properties and binding capabilities

Patterning of functionalized polymeric surfaces enables the adjustment of their characteristics and use in novel applications. We prepared breath figure (BF) films from three semifluorinated diblock copolymers, which all are composed of a polystyrene block and a semifluorinated one to compare their surface properties. “Click” chemistry was employed to one of the polymers, containing a poly(pentafluorostyrene) block to incorporate hydrophilic sugar or carboxylic acid moieties. The structure of the polymer alters the obtained porous morphology of the films. Contact angle (CA) analyses of the BF films reveals that the surface porosity increases water CAs compared with solvent cast films, and, in the case of hydrophobic polymers, leads to significant increase in the CAs of dodecane. The hydrophobicity of the BF films is further amplified by the removal of the topmost layer which leads in some cases to superhydrophobic surfaces. BF films containing glucose units are hydrophilic exhibiting water CAs below 90°. These glycosylated porous surfaces are shown to bind lectin Con A‐FITC or can be labelled with isothiocyanate marker. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41225.     

Structure and morphology of nanoporous zno and dark current‐Voltage characteristics of the glass/(TCO)/zno/poly[2,7‐(9,9‐dioctylfluorene)‐alt‐(5,5'‐bithiophene)/ag structure

The hybrid organic‐inorganic structure based on glass/(TCO)/nanoporous ZnO/poly[2,7‐(9,9‐dioctylfluorene)‐alt‐(5,5′‐bithiophene)]/Ag that was prepared by physical deposition has been investigated. The structure of the nanostructured ZnO obtained by magnetron sputtering was confirmed by X‐ray diffractometry (XRD) and energy dispersive X‐ray spectroscopy (EDX). Scanning electron microscopy (SEM) analysis proved the existence of short and interconnected zinc oxide (ZnO) fibers, which form a continuous porous network with pores having an average diameter of 100 nm. Current‐voltage (I‐V) curves of the glass/TCO/ZnO/PF‐BT/Ag hybrid structure are similar to those of typical p‐n junctions and stable until 90°C temperature. According to the I‐V characteristics, the dominant mechanism of current flow is based on the generation‐recombination of carriers in the depletion region at low direct biases and also on the injection of carriers at high biases. The reverse branch of the I‐V characteristic, calculated in log‐log scale, shows one segment with a power coefficient of 3/2 at room temperature. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42415.     

Effects of thickness and hydrophobicity of double microporous layer on the performance in proton exchange membrane fuel cells

In this paper, a multi-layer gas diffusion layer (GDL) is designed. The GDL consists of a single carbon paper backing layer and dual microporous layers (MPLs). Moreover, the effects of thickness and hydrophobicity of double MPL on the performance of proton exchange membrane fuel cells are investigated. From the test results of the water contact angle, conductivity, pore size distribution, and the polarization curve, it is found that the thickness adjustment increases the number of 0.5 to 7 μm and 20 to 100 μm pores in GDL, which is more conducive to water discharge. Therefore, the thickness adjustment is more favorable to the cell performance under high humidity. While the gradient hydrophobic design makes the MPL of the modified intermediate layer have a certain water-retaining capacity to humidify the reaction gas, which has better effect under low humidity. At last, the results show that the optimized GDL meets a limit power density of 1.772 W/cm² under 60% humidification and 1.600 W/cm² under 100% humidification.     

Sol–gel preparation of ultralow refractive index silica coatings with hydroxypropyl‐beta‐cyclodextrin as porogen

Ultralow refractive index films were prepared based on a base‐catalyzed sol–gel process using methyltriethoxysilane (MTES), tetraethylorthosilicate (TEOS) as co‐precursors, and hydroxypropyl‐beta‐cyclodextrin (HPCD) as porogen. After further modification by hexamethylisilazane (HMDS), the lowest refractive index of these silica coatings obtained from the hybrid sol was 1.05 and the static water contact angles of the coatings increased from 66.4° to 128.7°. The effect of weight ratio of HPCD to SiO₂ on the refractive index and on the formation of coating films were systematically studied. The data showed that the films prepared with HPCD as porogen got a pore diameter around 4 nm. Compared with those templates such as poloxamer (F127), HPCD not only perform well in decreasing the refractive index of films, but also eliminate light scattering caused by mesopore of the film, will have potential value in the field of surfactant‐templated methods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44686.     

Effect of solvents on morphology and polymorphism of polyvinylidene fluoride membrane via supercritical CO2 induced phase separation

Poly vinylidene fluoride (PVDF) membranes were prepared via supercritical CO₂ induced phase separation. The effects of solvent power on PVDF membrane morphology and polymorphism were investigated using N‐N‐dimethylformamide (DMF), triethyl phosphate (TEP), and their mixture respectively. The morphology evolution including cross‐section and surfaces were thoroughly studied by scanning electron microscope (SEM) and atomic force microscopy (AFM). The differences of solubility parameters between the solvent and PVDF affected the phase separation and the resultant morphology. The various crystalline phases of the membranes were mainly investigated by Fourier transform infrared spectroscopy (FTIR) and X‐ray diffractometer (XRD). Solvent with larger dipole moment tended to form polar β phase. Decreasing the difference of solubility parameters favored the formation of α phase. Furthermore, the effects of salt additive on PVDF membrane morphology and crystalline form were studied as well. Results turned out that lithium chloride (LiCl) induced a porous top surface and boosted the formation of β phase. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41065.     

Action of silicic acid derived from sodium silicate precursor toward improving performances of porous gelatin membrane

To gain an insight into understanding how the silica network generated from hydrolysis and condensation of silicic acid, derived from sodium silicate, enhancing hydrothermal stability and mechanical properties of the leather, and particularly which active groups playing a main role for interaction of silica with collagen protein molecules, herein, effects of incorporated amino or carboxyl groups on the properties of silicic acid modified gelatin (GE) membrane were intensively studied. We found when lots of amino groups were introduced by adding a modified melamine, the thermal denaturation temperature, uniformity of pore diameter distribution and mechanical strength of GE membrane distinctly increased, while incorporating plenty of carboxyl groups by adding low polymerization degree acrylic acid polymer, no obvious change of performances of GE film was discovered. In addition, utilization of γ-glycidoxypropyltrimethoxysilane had a positive effect on the porosity and flexibility of GE membrane. Importantly, our results indicated that hydrogen bonding probably played the most important role toward improving performances of porous GE film when treated with silicic acid. These findings are greatly beneficial for developing a chrome-free tanning technology based on silicon containing materials, and are also suggestive for fabricating porous silica-GE hybrid materials using sodium silicate as a precursor. © 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48912.     

A selective organosilica membrane for ethyl acetate dehydration by pervaporation

Organosilica bis(triethoxysilyl) ethane (BTESE) membranes were explored for pervaporation dehydration of binary and ternary mixtures of ethyl acetate (EA) by undiluted sol coating combined with flash firing. Three BTESE membranes (M1, M2, and M3) were fabricated on macroporous supports by varying BTESE concentrations (0.5, 2.5, and 5 wt% BTESE, respectively) in polymer sols. The membranes were characterized by DLS, SEM, FTIR, XRD, contact angle, AFM, and pervaporation performance to discuss the effect of the BTESE contents in the polymer sol on the formation and dehydration performance of resulting organosilica membranes. It was found that 5 wt% loading of BTESE led to a highly selective membrane for dehydration of EA/H₂O mixture. Among the synthesized membranes, M3 delivered flux of 0.84 ± 0.05 kg.m⁻².h⁻¹ with a selectivity of >10,000 for EA/H₂O mixture (98/2 wt%) at 60°C. The time course of pervaporation dehydration for the EA/H₂O mixture (95/5 wt%) confirms the stability of BTESE membrane in the investigated time period of 120 h. Further, the membrane exhibited excellent selectivity larger than 10,000 for separation of ternary mixtures (90/2/8 wt%) of ethyl acetate/ethanol/water and n-propyl acetate/isopropanol/water respectively, the composition of which is similar to the top product of the distillation column used in the industrial esterification process. The best separation performance and excellent acid stability of BTESE membranes in this study suggest that the simple synthesis protocol of undiluted sol coating and flash firing will provide a cost-effective, quick, and efficient synthesis route for practical membrane based applications.     

Latex‐templated biomineralization of silica nanoparticles with porous shell and their application for drug delivery

A latex‐templating method for synthesizing the core‐shell silica nanoparticles (NPs) with porous shell was developed via biomineralization in the presence of poly[2‐(methacryloyloxy)ethyl] trimethylammonium chloride (pDMC)‐modified polystyrene latex. Calcination of the as‐obtained SiO₂ NPs led to the removal of the latex core and consequently to hollow silica NPs with porous shell. In particularly, the microstructure and thickness of silica shell could be controlled by simply changing the reaction parameters of silicification. Furthermore, facile encapsulation of a drug molecules and its sustained release were demonstrated. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44200.     

Effective treatment for environmental enhancing the performance of undesirable agro-waste in production of carbon nanostructures as adsorbent

The work in this article deals with enhancing the performance of rice straw (RS) for production of carbon nanostructures (CNSs), as aqueous phase adsorbents, as well as benefit solution for disposing of this undesirable waste and for avoiding the environmental risk from burning. In this respect, controlling the constituents of RS by enzymatic treatment, followed by hydrothermal treatment and carbonization was carried out. The benefit role of the performed treatments was supported via comparing these CNSs with those obtained from RS pretreated by chemical pulping processes; moreover, literature reported CNSs. Results deduced from SEM and TEM analyses showing that, the two investigated CNSs samples have different surface morphologies and comprised of graphitic carbons as nodules and multi-layer graphene sheets. The investigated RS-based CNSs own numerous of oxygen-containing functional groups with low specific surface area and high mesopore volume; thus, they exhibited high iodine number of 959 and 863 mg/g, respectively. The CNSs from hydrochar of peroxidase treated RS has higher uptake to methylene blue (MB) dye (358 mg/g) than that produced from hydrochar of cellulase treated RS (202 mg/g), this may be related to its unique nanostructure. Both values are higher than that of reported CNSs, which obtained from chemical pulping processes (~ 54–119 mg/g). The adsorption of MB dye is well-fitted with Langmuir and described by pseudo-second order kinetic model.     

Fabrication of efficient pervaporation desalination membrane by reinforcement of poly(vinyl alcohol)–silica film on porous polysulfone hollow fiber

Pervaporation membrane technology is commercially successful in the dehydration of organic solvents, and the technology has potential for seawater desalination with high recovery because of its capability to treat highly saline water. But to make the technology advantageous over the other available membrane desalination technologies in terms of productivity flux without additional energy cost, the selective barrier layer is required to be extremely thin, defect‐free, hydrophilic, and selective to water. In this work, we prepared an efficient membrane by reinforcing a highly water‐permeable but continuous barrier layer of poly(vinyl alcohol)–silica (PVA‐SiO₂) hybrid material on porous polysulfone hollow fibers. The PVA‐SiO₂ in acidified and hydrated ethanol was aged at room temperature for a period to allow solvent evaporation to obtain the solution concentration desired for the reinforcement. The reinforced hollow fiber membrane with optimal PVA‐SiO₂ barrier layer thickness exhibited a performance with a flux of 20.6 L m^?2 h^?1 and 99.9% salt rejection from a saline feed of 2000 ppm NaCl at 333 K. The effects of PVA‐SiO₂, temperature, and feed salinity on the pervaporation performance of the membrane were also studied. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45718.     

Influence of solvent and nanoparticles on the morphology and gas separation properties of copolyimide membranes

In this study, the effect of solvent type and nanoparticles of silica and zeolite 4A on the gas separation properties of polyimide (PI) membranes were investigated. Gas separation of the membranes based on pure solvents of dimethylformamide (DMF), n-methyl-2-pirrolidone (NMP), dimethylacetamide (DMAc), and dimethylsulfoxide (DMSO) were studied. The prepared PI membranes using DMAc and DMSO showed the highest selectivity and permeability, respectively. In this regard, the influence of their mixing on transport properties of the PI was evaluated. The prepared membrane using the mixture of DMSO/DMAc with the volume ratio of 1:3 showed the best gas separation performance in comparison to the Robeson's upper bound. Incorporation of 20 wt% of silica and zeolite 4A nanoparticles into the PI membrane indicated that the selectivity of CO₂/CH₄ increased from 39.4 to 57.6 and 68.5, respectively. Besides, gas transport properties of the PI-based mixed matrix membranes were satisfactory predicted by modified Maxwell model. Furthermore, characteristic parameters of the encapsulated particles by interfacial layer were determined.     

Preparation of highly selective nanofiltration composite membranes based on a novel soluble rigidly contorted monomer

Nanofiltration composite membranes with high selectivity are one of the most critical cores in water treatment, and regulating the surface charge and pore structure of active separation layers in thin film composite membranes is one of the most effective means to improve the selectivity of composite membranes. This article synthesized a novel monomer with positive charge and a rigid twisted Tröger's base structure (named TBDA-SO₃), which was manipulated to improve the microporous structure and surface charge of the composite membrane. By interfacial polymerization, TBDA-SO₃, and piperazine were co-reacted with trimesoyl chloride to successfully prepare positively charged, highly selective, and strongly microporous polyamide composite nanofiltration membranes. The best-performing composite nanofiltration membrane in this article has a permeability similar to that of the control group's poly(piperazine amide) (PPA) membrane (pure water flux, 7.8 L m⁻² h⁻¹ bar⁻¹), but has excellent divalent cation selectivity (52.57), which is 4.4 times that of the control group's PPA membrane.     

Variable infrared emissivity based on polyaniline electrochromic device influenced by porous substrate

Polyaniline (PANI) films and its electrochromic devices based on various porous substrates were obtained by electrochemical deposition. The pore size distribution of the porous substrate has shown important influence on the infrared emissivity variation (∆ε) of the device. Morphology and structure of PANI were characterized by scan electronic microscopy (SEM) images and Fourier transform infrared spectra (FTIR). SEM images present the morphology difference of PANI on different substrates, which suggest that large pores will prevent PANI particles from forming orderly and compactly films. FTIR spectrum indicates that pore size of substrates affects the orientation of PANI chains. Furthermore, electrochemical properties and stability of PANI films were analyzed by cyclic voltammetry (CV) curves. And the CV curve revealed that the generation of irreversible degradation products is the reason for poor stability of PANI films. Finally, greatly improved ∆ε of 0.559 in 3–5 μm waveband and 0.39 in 8–14 μm waveband is achieved by choosing a small pore substrate.