Pickering emulsions stabilized with PANI-NP. Study of the thermoresponsive behavior under heating and radiofrequency irradiation

Micrometric Pickering emulsions in 1-octanol or cyclohexane were stabilized with water-dispersible electroactive polyaniline nanoparticles (PANI-NP). The emulsions were characterized by optical and electronic microscopy as well as spectroscopic techniques. It was demonstrated that nanoparticles maintain their functional properties (e.g., pH sensitivity and electromagnetic absorption) in the emulsion. Furthermore, as a proof of concept, smart Pickering emulsions employing PANI-NP stabilized with a thermosensitive polymer (PNIPAM) were obtained. The thermal behavior of the obtained structures was evaluated by turbidimetric techniques and an IR camera. The thermoresponsive emulsions have shown an important increment of the local temperature (>12°C) under radiofrequency (RF) irradiation. Phase transition of PNIPAM induced by heating or RF absorption provokes the breaking of the emulsions. In this context, the proposed systems herein could induce endothermal reactions carried out in organic solvents. Besides, Pickering emulsions formed by using electroactive PANI-NP could be applied in several medical or industrial applications.     

Synthesis of a novolac‐based 3‐aminopropylsiloxane resin and its application for the removal of Cu2+, Cr3+, and Ni2+ from electroplating wastewater

Novolac resin was modified with 3‐aminopropyltrimthoxysilane to obtain phenol‐formaldehyde‐aminopropylsiloxane resin (PF‐APS). Fourier transformation infra‐red spectra, thermogravimetric analysis, elemental analysis, and pH‐metric titration were used to characterize PF‐APS. Its chemical formula was suggested to be C₁₄H_12.49N_0.1O₂Si_0.1. The resin shows high experimental metal ions uptake capacity within short time of equilibration. The metal capacity was determined by atomic absorption spectrometry to be 0.787 mEq Cu/g. Maximum separation efficiencies of Cu²⁺, Cr³⁺, and Ni²⁺ from aqueous solutions on PF‐APS were at pH 8.0 and time of stirring 60 min; 94.0%, 90.8%, 83.2%, respectively. No significant interference from the background ions Na⁺, Cl^?, and was observed on the separation process. The heavy metal ions were eluted using 0.01 mol L^?1 EDTA at 65°C releasing >94% of the separated metal ions. The method of separation was applied successfully to remove the heavy metal ions Cu²⁺, Cr³⁺, and Ni²⁺ from electroplating wastewater from Dekirnis, Dakahlia Governorate, Egypt. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40993.     

Characterization of multifunctional PAN/ZnO nanofibrous composite filter for fine dust capture and photocatalytic activity

The multifunctional air filter, which can provide low resistance to airflow, was prepared from polyacrylonitrile (PAN) nanofibers (NFs) by impregnating zinc oxide (ZnO) nanoparticles (NPs) with photocatalytic activity. Incorporation of ZnO NPs improved the surface roughness and electrostatic charge of electrospun NFs. The PAN/ZnO composite filter with 12 wt%-ZnO showed a filtration efficiency of 98.8% and a pressure drop of 48 Pa for 300 nm aerosol particles, resulting in a quality factor of 0.092 Pa⁻¹. In addition, PAN/ZnO composite exhibited excellent photocatalytic activity in methylene blue (MB) decomposition at 100 and 70.2% efficiencies, respectively, under UV and visible light.     

Spray-coated PDMS/PVDF composite membrane for enhanced butanol recovery by pervaporation

In this study, spray-coating was used to prepare dihydroxypolydimethylsiloxane (PDMS) composite membranes with high flux and separation factor for biobutanol recovery from aqueous solution. A thin, smooth, and defect-free PDMS layer was prepared by spray-coating on polyvinylidene difluoride ultrafiltration membrane with little PDMS penetration. The effects of process parameters for membrane fabrication and pervaporation on membrane performance were investigated. A membrane with 2 μm active layer was obtained with a high flux of 1306.9 g/m² h. The optimal membrane with the highest pervaporation separation index (PSI) (19.15 kg/m² h) showed a total flux of 530.6 g/m² h and a separation factor of 36.1 at 37°C, and a PSI of 65.61 kg/m² h and a flux of 1927.0 g/m² h at 70°C. Membrane performance was affected by feed composition and temperature. Acetone-butanol-ethanol solution and fermentation broth gave lower butanol fluxes and separation factors compared to butanol model solution.     

The synthesis of modified alginate flocculants and their properties for removing heavy metal ions of wastewater

A new flocculant was synthesized through the modification of sodium alginate with thiosemicarbazide. In the preparation, amino thiourea groups which had excellent adsorption properties for heavy metal ions were introduced to the flocculant. The structure of the flocculant was confirmed by elemental analysis, Fourier transform infrared, UV spectrophotometry, nuclear magnetic resonance, and thermal analysis. The flocculation behaviors of the flocculant for three heavy metal ions were investigated. The results showed that the removal rates of the flocculant for Pb²⁺, Cd²⁺, and Cu²⁺ reached up to 97.8%, 86.3%, and 80.0%, respectively, and the flocculation capacities were as high as 489, 215, and 160 mg/g, respectively. The excellent adsorption was ascribed to the double effects of electronic interaction and chelation between the flocculant and heavy metal ions. The flocculant had particular flocculation selectivity for Pb²⁺ in the mixed heavy metal ion solutions containing Cd²⁺or Cu²⁺, respectively. The flocculation process corresponded to Langmuir isotherm model, the flocculation kinetics agree with pseudo second order. The flocculant had potential applications for treatment of wastewater. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46577.     

Highly porous,water-swellable,and reusable chelating polymeric gels for heavy metal ion removal from aqueous waste

Sequestration and removal of heavy metal ions from aqueous solutions pose multiple challenges. Ease of synthesis, high adsorption capacity and ease of regeneration are important considerations in the design of polymeric adsorbent materials developed for this purpose. To meet this objective, a new approach was used to design and synthesize a highly porous polystyrene-based resin (IDASR15) bearing iminodiacetate functional groups in every repeat unit by free radical polymerization with N, N'-methylenebisacrylamide as crosslinker followed by base hydrolysis. The physiochemical chemical properties of the resin were characterized by Fourier transform infrared spectroscopy, scanning electron microscope, equilibrium swelling value (ESV) and thermogravimetric analysis. Metal uptake capacity of IDASR15 towards low concentrations of various toxic heavy metal ions such as Cu²⁺, Cd²⁺, Mn²⁺, Zn²⁺, Pb²⁺, Ni²⁺, Co²⁺, Co³⁺, Cr³⁺, Fe²⁺, Fe³⁺, and Al³⁺ were investigated from their aqueous solution by batch method and found to be 0.943–2.802 mmol/g. The maximum capacity was 2.802 mmol/g obtained for Cu²⁺ ion at pH 5. The potential for regeneration and reuse has been demonstrated with Cu²⁺ ion by batch and column methods. The reported results suggest that IDASR15 is a highly efficient and porous complexing agent for commonly found toxic metal ions in aqueous streams with a high ESV of 68.55 g of water/1.0 g of IDASR15. It could also be reused ~99.5% of adsorption efficiency which is very promising and holds significant potential for waste-water treatment applications.     

Structure characterization and adsorption properties of tetraethylenepentamine ion exchange fiber

A novel tetraethylenepentamine ion exchange fiber (TAIEF) was prepared using polypropylene grafted styrene (PP‐g‐ST) fiber as raw material. The chemical structure of TAIEF was characterized using infrared spectrum (IR) method. TAIEF had good appearance and shape after reaction in SEM images, the TGA curves revealed that both PP‐g‐ST fiber and acetyl PP‐g‐ST fiber had good thermal stability below 250 °C, and the weight loss rate of TAIEF is 9% from 50 °C to 200 °C obtained by TGA. TAIEF adsorption capacity to Fe(III) is larger than that of In(III) in the pH value 1.00 to 3.00, while the pH value is at 2.50 to 3.00, TAIEF adsorption capacity to Fe(II) and Zn(II) are smaller than that of In(III). The selective adsorption ability to Fe(III) is higher than In(III), and the selective absorptivity to In(III) is better than Fe(II) and Zn(II). The mechanism was explained of TAIEF favorable selective adsorption to In(III) and Fe(III) ions in mixed solutions. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44513.     

Facile synthesis of a triptycene-based porous organic polymer with a high efficiency and recyclable adsorption for organic dyes

Water contamination resulting from organic dyes has had severe detrimental effects on human health and environmental tolerance. To address this issue, a delicate strategy for taking host–guest function in porous organic polymers via a facile Friedel–Crafts reaction of triptycene and post-modification was achieved. By means of this route, a sulfonic acid functionalized triptycene-based porous organic polymer (TPOP–SO₃H) with a hierarchical structure and a desirable Brunauer–Emmett–Teller value of 1002 m²/g was synthesized this study. The TPOP–SO₃H material demonstrated a maximum adsorption capacity for methylene blue of 97.1 mg/g. Remarkably, an absorption efficiency of more than 90% of TPOP–SO₃H was observed even after five cycles. Therefore, such a hierarchical porous organic polymer can be highly recommended as one type of promising material for the treatment of organic dye-polluted wastewater. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47987.     

Regeneration of anion‐exchange resins with Mg/Al double‐metal hydroxides

Anion‐exchange resins (AERs) were regenerated with Mg/Al double‐metal hydroxides as the regenerant. Electrical conductivity breakthrough curves were adopted to estimate the relatively rapid regenerative effect of the AERs. The results show that the optimal regenerative effect of AER was obtained when the Mg/Al molar ratio was 3 and the dosages of Mg and Al hydroxides were 0.045 and 0.015 mol, respectively. The highest effluent water yield was obtained at an AER/cation‐exchange resin volume ratio of 2:1. Characterization through scanning electron microscopy, X‐ray diffraction, and thermogravimetry–differential thermal analysis showed that the regenerant was transformed and exhibited the distinguishing features of Mg/Al layered double hydrotalcites. Cycle experimentation showed that all calcined products effectively regenerated the fouled resins, and the regenerative mechanism was then established. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42928.     

Specific heavy metal ion recovery with ion‐imprinted cryogels

In this study, the functional monomers, N‐methacryloyl‐l ‐aspartic acid and N‐methacryloyl‐l ‐cysteine were synthesized through a reaction between appropriate amino acids and methacryloyl chloride. Then, Pb(II) or Cd(II) ion‐imprinted 2‐hydroxyethyl methacrylate based cryogels were prepared by free radical polymerization method under partially frozen conditions. Following the characterization of matrices, adsorption of heavy metal ions was examined in batch mode from aqueous solution considering several parameters affecting the adsorption performance. The actual adsorption capacities were 44.5, 65.3, and 86.7 mg/g for Cd‐1, Cd‐2, and Cd‐3 cryogels meanwhile those were 41.9, 86.3, and 122.7 mg/g for Pb‐1, Pb‐2, and Pb‐3 cryogels, respectively at optimum pH: 5.5. By increasing temperature, adsorption capabilities of both cryogels were inhibited because of the electrostatic nature of coordinated covalent bonds and collapsing of coordination spheres. The adsorption process was very fast, the equilibrium adsorption was achieved in about 60 min, which was directly related to macroporous structure and interconnected flow‐channels of cryogels. Kinetics and adsorption isotherms were also studied. Langmuir isotherms and pseudo‐second order kinetic model were well suited to adsorption data, which also indicated that the process occurred without any diffusion restrictions or steric hindrances. Finally, the competitive adsorption studies were performed using multi‐ion containing synthetic wastewater to show whether the cryogels developed are suitable for specific heavy metal recycling or not. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43095.     

Three-dimensionally cross-linked styrene-methyl methacrylate-divinyl benzene terpolymer networks for organic solvents and crude oil absorption

The present study reports, high-performance polymer absorbents for crude oil and organic solvents based on 3D cross-linked polystyrene-polymethyl methacrylate/divinyl benzene (PS-PMMA/DVB). The preparation of the 3D cross-linked polymer absorbents has been carried out by bulk polymerization method using styrene (S) and methyl methacrylate (MMA) monomers in the presence of DVB with azobisisobutyronitrile as an initiator. The prepared cross-linked polymer absorbents were characterized by Fourier transform infrared spectroscopy, thermogravimetric and differential scanning calorimetry, and dynamic mechanical analyses. The absorption kinetics, thermodynamics of the absorption process as well as the recyclability of the cross-linked polymer absorbents were investigated in detail. The developed 3D cross-linked PS-PMMA/DVB absorbents have demonstrated excellent absorption capacities for both organic solvents and crude oil. For instance, the developed polymer absorbent (PS-PMMA/DVB [1 wt%]) shows a maximum absorption capacity of 12 g/g for chloroform_, 6 g/g for tetrahydrofuran, and 3 g/g for crude oil. The absorption capacities by the polymer absorbents show a direct relationship with the polarity of the solvents. Moreover, the change of absorption capacity after several repeated cycles of absorption/desorption was only marginal. The demonstrated absorption capacities and the excellent recyclability make polymer absorbents as potential candidates for the oilfield applications and produced water treatments.     

Synthesis and characterization of salep sulfate and its utilization in preparation of heavy metal ion adsorbent

A multicomponent polysaccharide obtained from dried tubers of certain natural terrestrial orchids was chemically modified by sulfonation using chlorosulfonic acid–dimethylformamide (HClSO_3–DMF) complex as a reagent. For a structural characterization of salep sulfate ¹H nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR) spectra, and Thermogravimetric analysis (TGA) curves were recorded. The sulfate content of modified salep was determined using elemental analysis. This modified biopolymer was used to prepare a new environment‐friendly heavy metal ion adsorbent, salep sulfate‐graft‐polyacrylic acid hydrogel (SS‐g‐PAA). Swelling rate and equilibrium water absorbency in various pH and saline solutions were investigated to study the effect of salep sulfate on swelling behavior of the hydrogel. In addition, the effect of sulfate content on heavy metal ion adsorption from aqueous solution was investigated. The results show that SS‐g‐PAA can effectively remove heavy metal ions (Co²⁺, Zn²⁺, Cu²⁺) from aqueous solution and swelling behavior of the hydrogels highly dependent on the amount of sulfate group on corresponding modified polysaccharide. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3001–3008, 2013     

Synthesis of a branched photosensitive copolymer and its application for negative‐type photoresists

Novel branched copolymers, poly(styrene‐alt‐maleic anhydride) (BPSMA), were synthesized through mercapto chain‐transfer polymerization with styrene, maleic anhydride (MA), and 4‐vinyl benzyl thiol (VBT). Then, the hydroxyl of hydroxyethyl methacrylate was reacted with MA to synthesize branched photosensitive copolymers, p‐BPSMAs. Fourier transform IR spectroscopy and ¹H‐NMR indicated that the synthesis was successful. Gel permeation chromatography indicated that the molecular weight decreased with increasing content of VBT. The thermal properties were characterized by thermogravimetric analysis; the results show that the thermal decomposition temperature of the BPSMAs was greatly enhanced. Real‐time IR was used to evaluate the UV‐curable kinetics of the p‐BPSMAs; the results show that the p‐BPSMAs could rapidly photopolymerize under UV irradiation in the presence of photoinitiators. Moreover, the photoresist based on the p‐BPSMAs exhibited improved photosensitivity when the VBT content increased, and the photoresist with 12 mol % VBT content had a low value of the dose that retained 50% of the original film thickness (10 mJ/cm²), and a 50‐μm resolution could be achieved compared to a linear photoresist. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42838.     

Synthesis,spectral analysis,and catalytic activity of poly(aniline‐co‐congored)–metal oxide nanocomposites

Electrically conducting, water‐soluble fluorescent copolymer nanocomposites were synthesized by a solution polymerization method under different experimental conditions in the presence of CuO and V₂O₅ nanoparticles. The prepared copolymer nanocomposites were characterized with analytical tools, including Fourier transform infrared spectroscopy, ultraviolet–visible (UV–vis) spectroscopy, and fluorescence emission spectroscopy. The order of copolymerization was determined on the basis of the UV–vis absorption spectra and fluorescence emission spectra. The copolymer–CuO nanocomposite system exhibited the highest electrical conductivity. The scanning electron microscopy image showed the presence of more CuO nanoparticles on the surface of the copolymer. Furthermore, the catalytic activity of the copolymer nanocomposites was tested for the reduction of p‐nitrophenol. All three types of polymer systems exhibited almost the same apparent rate constant values. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46469.     

Synthesis and studies on core–shell type anion exchange resins based on a hybrid polymeric support

In pursuit for new materials for recovery of noble metals, novel anion exchangers, based on new type of core–shell polymeric supports have been synthesized. The designed matrices, with reactive chloromethyl groups concentrated on a surface of the polymeric base, the Amberlite XAD‐4 adsorbent, have been modified using ethylenediamine and polyethyleneimine. The obtained ion exchangers were employed in processes of sorption of gold, platinum, and palladium chlorocomplexes, then, they were compared to similar resins based on volumetric polymeric supports. The studies covered porosity measurements, determination of sorption behavior in the presence of counter ions as well as kinetic and column studies. Ultimately, an attempt to access a core–shell character of the resins has been made using digital‐optical microscopy. The proceeded analyses allowed to determine the localization of the resins’ functionalities and their advantages over traditional ion exchange resins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43841.     

Preparation and evaluation of aconitine imprinted microspheres and its application to body fluid samples

To extract aconitine from body fluid samples, aconitine‐molecularly imprinted polymer microspheres with the optimum molar ratios of template/monomer/cross‐linker (1:8:40) as selective sorbents were synthesized by precipitation polymerization. Excellent retention of aconitine on the molecularly imprinted microspheres (MIMs) cartridge was achieved by optimizing the MISPE process, and the binding capacity reached 0.802mg/g, yielding an imprinting factor of 4.76. The MIMs also showed high selectivity for aconitum alkaloids, but not for other kinds of poisonous alkaloids. High recoveries (>89%) for aconitine, hypaconitine, and mesaconitine were got in spiked serum samples. The working curves show linear dependence on aconitine concentration in the range of 2.0–0.1 µg/mL, and the detection limits of aconitine, hypaconitine, and mesaconitine were 16.7, 18.3, 10.2 ng mL^–1, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Direct dual layer spinning of aminosilica/Torlon® hollow fiber sorbents with a lumen layer for CO2 separation by rapid temperature swing adsorption

The direct dual layer spinning of Torlon^®/silica hollow fibers with a neat Torlon^® lumen layer is reported here for the first time. The dual layer fibers containing a porous Torlon^®/silica main structure and a dense, pure Torlon^® polymer bore‐side coating provide a simplified, scalable platform from which to construct hollow fiber amine sorbents for postcombustion CO₂ capture. After fiber spinning, an amine infusion process is applied to incorporate PEI into the silica pores. After combining dilute Neoprene treatment followed by poly(aramid)/PDMS treatment, a helium permeance of the fiber sorbents of 2 GPU with a He/N₂ selectivity of 7.4 is achieved. Ten of the optimized amine‐containing hollow fibers are incorporated into a 22‐inch long, 1/2 inch OD shell‐and‐tube module and the module is then exposed on the shell side to simulated flue gas with an inert tracer (14 mol % CO₂, 72 mol % N₂, 14 mol % He [at 100% R.H.]) at 1 atm and 35°C in a RTSA system for preliminary CO₂ sorption experiments. The fibers are found to have a breakthrough and equilibrium CO₂ capacity of 0.8 and 1.2 mmol/g‐ dry fiber sorbent, respectively. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41845.     

Facile enzymatic preparation of fluorescent conjugated polymers of phenols and their application in sensing

The recognized drawback of utilizing metal catalysts for the synthesis of fluorescent conjugated polymers (CP) is the requirement for extensive purification to ensure complete removal of residual catalyst that would otherwise quench the fluorescence. In addition, typical synthesis of fluorescent CP involves multiple steps, monomers and solvents with varying levels of toxicity. This work demonstrates the possibility of utilizing oxidoreductase enzymes as the catalyst, for the one step polymerization of naturally occurring phenols to yield fluorescent conjugated polyphenols. The metal in the active site of the enzyme remains chelated during the synthesis allowing the polymers to be fluorescent as synthesized without the need for extensive purification. Three natural phenols, 4‐hydroxyphenylacetic acid, hydroxytyrosol, and chlorogenic acid were polymerized using Horseradish peroxidase as the biocatalyst. Spectroscopic techniques, UV–vis, Fourier transform infrared Spectroscopy–Attenuated Total Reflectance, and fluorescence, are used to characterize chemical structure and photoluminescence of these polymers. The polyphenols exhibit fluorescence with significant stokes shift in the range 30–100 nm rendering them useful in fluorescence quenching‐based sensors. Preliminary studies on use of these polymers, in the detection of nitro‐aromatic compounds in solution through using fluorescence‐quenching are also presented. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46496.     

Polymer electrets and their applications

Polymer electrets have revealed great potential application in electromechanical devices because of the low weight, large quasi-piezoelectric sensitivity, and excellent flexibility. For an electret, a permanent and macroscopic electric field exists on the surface, principally led by a macroscopic electrostatic charge on the surface or a net orientation of polar groups inside the object. Here, progress in the development of polymer electrets is reviewed. After a brief retrospect of the research courses and those typical polymer electrets that are classified into fluorine polymer and nonfluorine polymer, we present a survey on the charging methods, including corona, soft X-ray, contact, thermal and monoenergetic particle beams. The latest representative applications (i.e., power harvesting, sensors, field effect transistors, and biomedicine) based on polymer electrets are also summarized. Finally, we complete this review with a discussion on perspectives and challenges in this field.