Terephthaloyl Chloride Research Articles

Structural Modifications of Polyethylenimine to Control Drug Loading and Release Characteristics of Amorphous Solid Dispersions.

Crystalline drugs with low solubility have the potential to benefit from delivery in the amorphous form. The polymers used in amorphous solid dispersions (ASDs) influence their maximum drug loading, solubility, dissolution rate, and physical stability. Herein, the influence of hydrophobicity of crosslinked polyethylenimine (PEI) is investigated for the delivery of the BCS class II nonsteroidal anti-inflammatory drug flufenamic acid (ffa). Several synthetic variables for crosslinking PEI with terephthaloyl chloride were manipulated: solvent, crosslinking density, reactant concentration, solution viscosity, reaction temperature, and molecular weight of the hyperbranched polymer. Benzoyl chloride was employed to cap amine groups to increase the hydrophobicity of the crosslinked materials. Amorphous deprotonated ffa was present in all ASDs; however, the increased hydrophobicity and reduced basicity from benzoyl functionalization led to a combination of amorphous deprotonated ffa and amorphous neutral ffa in the materials at high drug loadings (50 and 60 wt %). All ASDs demonstrated enhanced drug delivery in acidic media compared to crystalline ffa. Physical stability testing showed no evidence of crystallization after 29 weeks under various relative humidity conditions. These findings motivate the broadening of polymer classes employed in ASD formation to include polymers with very high functional group concentrations to enable loadings not readily achieved with existing polymers.

Fluorescence determination of tannic acid imprinted in conjugated hypercrosslinked polymers by Friedel-Crafts acylation.

A molecularly imprinted hypercrosslinked polymer (HCP) was synthesized from the polymerization of mesitylene monomer, terephthaloyl chloride crosslinker, and tannic acid (TA) template through FeCl3-catalyzed Friedel-Crafts acylation. The TA-imprinted HCP (TAHCP) was capable of IUPAC Type I mesoporosity, with specific surface area of 1258 m2 g-1, monolayer adsorption capacity of 289 cm2 g-1, pore sizes ranging from 4.4 to 12.6 Å, amorphous morphology, and characteristic absorption and emission bands. The extended π-conjugation framework of TAHCP was endowed with 385-nm fluorescent emission at 310-nm excitation. The fluorescence intensity of TAHCP could be dynamically quenched by TA and was linearly correlated with 20-1000 nM TA concentrations on the Stern-Volmer plot in the optimized conditions of pH 5.5 buffer, 100 μg mL-1 TAHCP, and 3.5 min equilibrium. The relative standard deviation (RSD) for 50 nM TA was 3.4% (n= 5), and the limit of detection was 6.2 nM based on the 3σ of the TA blanks). For 50nM TA, the imprinted factor was calculated to be 7.8, and the selectivity for 250 nM interferents, including ions, organic acids, saccharides, amino acids, and caffeine, which are commonly found in beverages, was 7.5-9.5, except for gallic acid (1.2). The recoveries of TA spiked in tea and juice beverages at three levels (10-150 nM) were 93.6-101.9% (RSD= 3.6-4.3%).

Synthesis and study of block copolymer polyarylates

In order to reduce the viscosity of a polyarylate melt based on phenolphthalein and terephthalic acid dichloride with a glass transition temperature of 280°C, polyarylate-polysulfone block copolymers with a glass transition temperature of 240 to 260°C capable of processing through a melt at 340°C were synthesized and studied.

A highly permeable porous organic cage composite membrane for gas separation

We proposed a facile porous organic cage (POC) composite membrane fabricated with the RCC3 cage crosslinked by terephthaloyl chloride for CO2/N2and CH4/N2separation. The amine-rich subnanochannel provided by RCC3 promoted the rapid penetration of CO2.

Facile fabrication of ceramic-polymeric nanocomposite membrane with special surface wettability using amino decorated NH2-SiO2@SiC nanopowder for production of clean water from oily wastewater

Given the huge market potential of treating oily wastewater, a ceramic membrane with special surface wettability was fabricated by covalently decorating amino-functionalized silicon carbide (NH2-SiO2@SiC) as an active layer on alumina support. The NH2-SiO2@SiC was synthesized by growing a layer of silicon dioxide (SiO2) on silicon carbide (SiC) leading to silicon dioxide loaded silicon carbide (SiO2@SiC). Then amino (-NH2) functionalization of SiO2@SiC was carried out through 3-triethoxysilylpropylamine (APTES) yielding NH2-SiO2@SiC. The NH2-SiO2@SiC was covalently deposited as active layer on alumina support through interfacial polymerization with terephthaloyl chloride (TPC) leading to SiO2@SiC/polyamide nanocomposite decorated on alumina (SiO2@SiC/PA@Al2O3) ceramic membrane. The SiO2@SiC/PA@Al2O3 ceramic membrane was thoroughly characterized by several membrane characterization techniques including water and oil contact angles, SEM (scanning electron microscopy), elemental mapping, EDX analysis (energy dispersive x-ray) and ATR-FTIR (Attenuated Total Reflectance Fourier Transform Infrared spectroscopy). The SiO2@SiC/PA@Al2O3 ceramic membrane was applied for sepraration of surfactant stabalized oil-in-water (O/W) emulsion feed. The effect of increasing O/W emulsion concentration (33.75–250 ppm) was studied by varying the amount of oil in the emulsion. The ceramic membrane was able to maintain a separation efficiency of > 98 % with permeate flux of 270 L/m2.h at a transmembrane pressure of 2 bar. The long-term filtration tests revealed that SiO2@SiC/PA@Al2O3 ceramic membrane retained its separation efficiency at > 98 % for 420 min when 125 ppm O/W emulsion was used as feed. The SiO2@SiC/PA@Al2O3 ceramic membrane showed a potential of treating a high concentration (250 ppm) surfactant stabalized O/W emulsion.

Supramolecular enzymatic membranes comprising of β-cyclodextrin and laccase for efficient removal and desalination of small molecules

Nanofiltration (NF) is regarded as a great potential technique for efficient treatment of industrial dyes and pharmaceutical effluents, however, its application still faces the challenges due to the trade-off among permeance, selectivity and anti-fouling property. Herein, a novel supramolecular enzymatic membrane was designed and successfully fabricated based on β-cyclodextrin (CD) and laccase (Lac), with the former providing supramolecular transport channels and the latter offering the pollutant degradation property. Specifically, after the host-guest complexation of CD with polyethylene glycol (PEG), the generated CD@PEG supramolecules were introduced into interfacial polymerization (IP) via reacting with terephthaloyl chloride (TPC) to fabricate supramolecular membrane with “bead-like” channels. Furthermore, the laccase was immobilized onto the modified polysulfone (mPSf) surface to generate CD@PEG@Lac-TPC/mPSf supramolecular enzymatic membrane for high-efficiency catalytic degradation of membrane foulants. The CD@PEG-TPC/mPSf supramolecular membrane displayed excellent performance and operation stability for removal and desalination of small molecules, with pure water permeance up to 26.8 L·m−2·h−1·bar−1, and satisfactory NaCl/dye and NaCl/medicine separation factors. Moreover, CD@PEG@Lac-TPC/mPSf supramolecular enzymatic membrane showed an effective anti-fouling property with only 8.0 % permeance decline rate after 24 h continuous separation of tetracycline hydrochloride solution, suggesting its potential application for removal and desalination of small molecules.

Exploiting phase inversion for penta-amine impregnation of ultrafiltration support matrix for rapid fabrication of a hyper-cross-linked polyamide membrane for organic solvent nanofiltration

For the sake of recovery of precious organic solvents from industrial organic solvent waste stream or alternatively for recovery of active principle ingredient (API) synthesized in pharmaceutical companies, organic solvent nanofiltration (OSN) membranes have recently been emerged. A thin film composite (TFC) membrane was fabricated by using rapid membrane fabrication technique. The PA(TEPA-TCL)@PSU/PETP membrane was fabricated by penta-amine (TEPA) impregnation of polysulfone (PSU) matrix during phase inversion which in turn was reacted with terephthaloyl chloride (TCL) through interfacial polymerization (IP). The PA(TEPA-TCL)@PSU/PETP membrane was characterized by scanning electron microscopy (SEM), water contact angle (WCA), energy dispersive X-ray (EDX) analysis, ATR-FTIR and elemental mapping. The PA(TEPA-TCL)@PSU/PETP membrane was applied for OSN by using water, methanol, ethanol and isopropanol as solvents. When methanol was used as feed, it showed a permeate flux of 28 L m−2 h−1 (LMH) at 20 bar. An inverse relationship was found between viscosity and flux of the solvents. A feed composed of methanol and dyes (dyes were used as model pollutants) was used to evaluate the OSN performance of the membrane. Apparently, size exclusion mechanism was found to be responsible for rejection of dyes as EBT was rejected up to > 92 % and Congo red (CR; M.W. = 696.6 g mol−1) rejection reached > 96% while it stayed at ≈ 88 % for Methylene blue (MB; M.W. = 319.8 g mol−1). The UV-Visible analysis of feed and permeate was conducted which confirmed the rejection of CR and MB. Hence, the PA(TEPA-TCL)@PSU/PETP membrane was found to be efficient for the purification of organic solvents contaminated with organic dyes.

Didodecyl terephthalate, ditetradecyl terephthalate, and dioctadecyl terephthalate compounds as novel phase change materials for medium temperature applications

Some of the fatty alcohols; 1-dodecanol, 1-tetradecanol and 1-octadecanol reacted to terephthaloyl chloride to produce some novel solid-liquid phase change materials (PCMs). It resulted in stable fatty esters for use as PCMs at considerably higher temperatures. Acyl chloride of terephthalic acid and one of the fatty alcohols reacted at 80 °C. Fourier transform infrared (FT-IR) spectroscopy with an attenuated total reflection accessory and 1H nuclear magnetic resonance (1H NMR) spectroscopy was exploited for structural characterization. Surface morphology of the produced materials was investigated through polarised optical microscopy (POM). Thermal properties were determined by a differential scanning calorimeter (DSC) as thermal endurance limits were determined by a thermogravimetric analyser (TGA). Thermal energy storage (TES) properties like melting-crystallisation temperatures and latent heats were found in the range of 66.0–81.0 °C and 179.2–191.2 J/g respectively by using a DSC instrument. The results revealed that the Didodecyl terephthalate (DDDT), ditetradecyl terephthalate (DTDT) and dioctadecyl terephthalate (DODT) as PCMs were thermally reliable with respect to 1000 times accelerated thermal cycling. According to physicochemical properties, the produced materials are valuable for use at considerably high temperatures as organic PCMs, which was surprising as there are very little organic alternatives for those temperatures.

Effect of oligo(ethylene glycol) length on properties of poly(oligoethylene glycol terephthalate)s and their cyclic oligomers

We present here the effect of oligo(ethylene glycol) (OEG) segmental length on properties of cyclic oligo(oligoethylene glycol terephthalate)s (COEGTs) and their corresponding polymer counterparts, poly(oligoethylene glycol terephthalate)s (POEGTs). COEGT monomers were synthesized from terephthaloyl chloride with corresponding diethylene glycol, triethylene glycol, and tetraethylene glycol under pseudo-high-dilution conditions. As those large ring cyclic monomers are hard to be polymerized via traditional ring-opening polymerization, a cascade polycondensation-coupling ring-opening polymerization method is utilized to obtain high molecular weight POEGTs. The cascade polymerization mechanism is confirmed by the kinetics study. The structures of COEGTs and POEGTs were well characterized and their properties were studied to reveal the structure-property relationship. With the increment of OEG length in repeating units, the chain flexibility of POEGT and COEGTs is enhanced. As a result, the melting temperatures of COEGTs and glass transition temperatures of POEGTs decrease. On the other hand, the thermal degradation temperature of POEGTs and COEGTs increases due to the enhanced ether fraction and reduced ring strain. Solid-state polymer electrolytes based on POEGTs was prepared by blending with lithium bis(trifluoromethanesulfonyl)imide. The measured ionic conductivity increased with the OEG length in POEGT repeating units. Our results revealed the effect of OEG length on the structure-property relationship in cyclic oligo(ether ester)s and copoly(ether ester)s, providing a facile way to tune their properties.

Exploiting interfacial polymerization to fabricate hyper-cross-linked nanofiltration membrane with a constituent linear aliphatic amine for freshwater production

Humanity is facing a global challenge of dwindling water resources and the situation is intensifying due to growing population leading to excessive water pollution. Nanofiltration is an important membrane-based technology for the production of clean and potable water for domestic and industrial setups. Hyper-cross-linked polyamide thin film composite nanofiltration (HCPA-TFC-NF) membranes have been fabricated by using multifunctional amine 1 (possessing two primary -NH2 and two secondary -NH groups) and bifunctional terephthaloyl chloride 2 (TPC) through interfacial polymerization. The structure of the hyper-cross-linked polyamide network has been successfully confirmed by solid (CP-MAS) 13C NMR, XPS, AFM, FT-IR, elemental mapping, and EDX analysis. The membrane features such as surface morphology and hydrophilicity have been established by FE-SEM and water contact angle measurements. The FE-SEM analysis revealed the formation of uniform polyamide active layer on the surface of PS/PET support, and the pore structure of the membranes was tuned by studying the effect of curing temperature and curing time. The nanofiltration membranes efficiently rejected a series of divalent salts including MgCl2, CaCl2, Na2SO4, MgSO4, and NaCl using cross-flow filtration setup. Based on the cross-flow filtration performance, the best conditions for the membrane fabrication were found to be curing temperature of 80 °C with a curing time of 1 h. The highest salt rejection was observed in case of MgCl2 reaching to a value of 98.11% in case of HCPA-TFC-NF@M3 and it was found to be 97.45% in case of HCPA-TFC-NF@M2 while the rejection of MgCl2 was reduced to 94.59% in case HCPA-TFC-NF@M1. HCPA-TFC-NF@M2 showed NaCl rejection of 87.36%. The hydrofluoric acid treatment of HCPA-TFC-NF-M2 increased the water flux while keeping the rejection high. The HCPA-TFC-NF@M2 showed a rejection of >99% for EBT with a permeate flux of 75 LMH.

Main‐chain liquid‐crystalline polymers bearing different anion

ABSTRACT In this paper, d-camphoryl chloride, terephthaloyl chloride, hydroquinone and 2,3-dibromosuccinyl chloride were used as raw materials to synthesise the main-chain liquid crystalline polymers by condensation polymerisation. A series of main-chain ionic liquid crystalline polymers with triphenylphosphine as the cationic group were successfully prepared by grafting triphenylphosphine onto the liquid crystalline polymer. By characterisation, we found that the main chain ionic liquid crystal polymer containing quaternary phosphonium ions had low glass transition temperature, high ionic conductivity and strong antibacterial properties. The quaternary phosphonium ions-containing main-chain ionic liquid-crystalline polymers show Smectic A phase, and the main-chain liquid crystalline polymers show nematic phase. The antibacterial experiments showed that the quaternary phosphonium ions-containing main-chain ionic liquid-crystalline polymers had good antibacterial properties, and the antibacterial ability of the polymer was also enhanced with the increase of phosphorus content. In addition, the orientation structure of liquid crystal also had a significant influence on its antibacterial properties.

Exploring a combination of unconventional monomers for fabricating a hyper-cross-linked polyamide membrane with anti-fouling properties for production of clean water

A new hyper-cross-linked polyamide TFC NF membrane (M-I) was fabricated by using tetraethylenepentamine (TEPA) and terephthaloyl chloride (TPC). Fabricated membrane M-I was treated with 15 % hydrofluoric acid (HF) and membrane was regarded as M-2. Both membranes were thoroughly characterized by FESEM, ATR-FTIR, EDX analysis, Elemental mapping, and water contact angle (WCA). Performance of both membranes was evaluated in the form of permeate flux and rejection of Eriochrome Black T (EBT) along with salts (Na2SO4, MgSO4, MgCl2, NaCl and CaCl2) while anti-organic and antibiofouling performance of both of the membranes was studied by using Bovine Serum Albumin (BSA) as a model foulant while Escherichia coli and Staphylococcus aureus as model gram-negative and gram-positive bacterial strains. The membrane M-II showed better performance compared to the membrane M-I. The membrane M-II showed a permeate flux of 88.57 LMH at 24 bar with rejection of > 99 % of EBT and > 81 % of NaCl. The membrane M-II showed a decline in flux of merely 2.7 % with a flux recovery of 98.6 %. The bacteriostatic experiments demonstrated that the membrane M-II inhibited E. coli and S. aureus growth by 22.8 % and 77.5 %, respectively, after 24 h of incubation.

Sensitive determination of auxins in environmental water and peach beverage by hyper crosslinked polymer-based solid-phase extraction with high performance liquid chromatography-fluorescence detection

As plant regulators, auxins can promote plant growth. However, they have toxicity and may cause harm to humans. Due to their low concentrations in food sample matrices, the enrichment and analysis of trace auxins in food samples is a challenging work. In this work, a series of hyper crosslinked polymers (HCPs) were synthesized by Friedel-Crafts acylation to extract four auxins (indole-3-acetic acid, indole-3-propionic acid, indole-3-butyric acid and 1-naphthylacetic acid). Among these HCPs, the QP-TC-HCP, synthesized from p-quaterphenyl (QP) and terephthaloyl chloride (TC), showed the best adsorption performance for the auxins. It was then applied as the adsorbent for the solid-phase extraction of the auxins from environmental water and peach beverage samples, followed by high performance liquid chromatography-fluorescence detection. Under the optimized conditions, the limits of detection were 3.0–12.0 pg mL–1 for environmental water and 18.0–36.0 pg mL–1 for peach beverage sample. The method recoveries of the auxins for the spiked samples were in the range of 85.0–110.0%. The established method provided an alternative approach for the determination of auxins in food samples. In addition, different types of organic compounds were tested for the extraction by the QP-TC-HCP to assess its application potential and adsorption mechanism. It was concluded that the QP-TC-HCP had better extraction performance for the compounds with certain hydrophilicity and more hydrogen bonding sites.

NH2-CuO-MCM-41 covalently cross-linked multipurpose membrane for applications in water treatment: Removal of hazardous pollutants from water, water desalination and anti-biofouling performance

The current study was planned to fabricate a new set of membranes to target multiple application areas such as desalting, removal of micropollutants and antibiofouling performance. In-situ incorporated copper oxide to MCM-41 (CuO-MCM-41) was synthesized and amine (-NH2) functionalized by reacting with N1-(3-trimethoxy silylpropyl) diethylenetriamine (NTSDETA) yielding NH2–CuO-MCM-41. Different concentrations of NH2–CuO-MCM-41 were covalently cross-linked in polyamide active layer during interfacial polymerization (IP) between N, N′-bis(3-aminopropyl)ethylenediamine and terephthaloyl chloride (TPC) on polysulfone/poly ester terephthalate (PS/PET) support. The membranes were extensively characterized by Water Contact Angle (WCA), Scanning Electron Microscopy (SEM), Fourier Transform Infra-red (FTIR) spectroscopy, Energy Dispersive X-ray (EDX) analysis, Elemental mapping and Powder X-ray Diffraction (PXRD). From among the different versions of X-CuO-MCM-41/PA@PS/PET membranes, the 0.05%-CuO-MCM-41/PA@PS/PET membrane showed best performance in terms of rejecting a variety of salts, micropollutants and antibiofouling. The 0.05%-CuO-MCM-41/PA@PS/PET showed >98% rejection of MgCl2 and 78% rejection of caffeine with a permeate flux of 16 LMH at 25 bar. The 0.1-NH2-CuO-MCM-41inhibited S. aureus growth by 51.7%. Hence, the current strategy of membrane fabrication proved to be highly efficient for multipurpose applications in water treatment.

Porous organic cage supramolecular membrane showing superior monovalent/divalent salts separation

Nanofiltration process has been perceived as one of the promising approaches in desalination and separation of monovalent/divalent salts. Despite significant progresses has been made in permeability and salt rejection, the industrial separation for monovalent/divalent salts is limited by the insufficient selectivity for ions with different charges and sizes. This work firstly proposed a porous organic cage supramolecular membrane with topologically structured “window-to-window” channels for the fast transport of monovalent ions and water molecules. Specifically, porous organic cage (RCC3) molecule and nonpolar alkyl of dodecyltrimethylammonium bromide (DTAB) were assembled into supramolecular RCC3@DTAB through hydrophobic interaction by molecular recognition of polar cavity. Furthermore, terephthaloyl chloride (TPC) was employed as a crosslinker by interfacial polymerization to construct RCC3@DTAB-TPC supramolecular film onto the surface of polydopamine modified polysulfone (PSf) substrate. The results suggested that RCC3@DTAB-TPC membrane displayed a high permeability of 13.9 L m−2 h−1 bar−1, and attractive performance for monovalent/divalent salts separation and small molecule solutions desalination. The salt rejections to Na2SO4, MgSO4, NaCl and MgCl2 are 98.5%, 90.1%, 19.8% and 12.8%, and the selectivities of NaCl/Na2SO4 and NaCl/MgSO4 reached 42.6 and 7.8, respectively. Besides, the separation factors for NaCl/medicine and NaCl/dye mixtures are 95.5 of δNaCl/DG and 76.6 of δNaCl/CR, respectively. The excellent separation performance of RCC3@DTAB-TPC supramolecular membrane provides a new idea for developing high-efficiency membranes for monovalent/divalent salts separation.

Chemically crosslinked polyimide-POSS hybrid: A dielectric material with improved dimensional stability and dielectric properties

One kind of the leading polymers applied in microelectronic packaging is polyimide (PI)-tethered polyhedral oligomeric silsesquioxane (POSS) hybrids. However, a well-known problem is that PI-POSS hybrids usually suffer from the serious thermal expansion at elevated temperature, leading to deteriorated reliability in electronic devices. In this work, a series of PI-POSS hybrids is successfully fabricated using aminopropylisobutyl-POSS as a reactive filler, and then the phenolic hydroxyl groups on side chains of hybrids react with terephthaloyl chloride at room temperature to form a crosslinked network. The well-designed crosslinked network suppresses the thermal expansion and improves the dielectric properties of hybrids together with POSS. As an example, after 24 h of crosslinking reaction, the coefficient of thermal expansion of the crosslinked hybrid with 14.6 wt% POSS (CPIH-2-24H) is 24 ppm/K, revealing a 59% reduction against the unmodified PI (82 ppm/K). Meanwhile, the dielectric constant and loss of CPIH-2-24H are decreased by ∼27% (2.68 vs. 3.68) and ∼72% (0.007 vs. 0.025), respectively, compared with the corresponding values for the unmodified PI. These data indicate that the resultant crosslinked PI-POSS hybrids may be used as microelectronic packaging materials, and the work provides a feasible approach to restrict the thermal expansion of PI-POSS hybrids by room-temperature chemical crosslinking.

Fabrication of polypyrrole-graphitic carbon nitride nanocomposite containing hyper-cross-linked polyamide photoresponsive membrane with self-cleaning properties for water decontamination and desalination applications

A new photoresponsive hyper-cross-linked polyamide thin film nanocomposite nanofiltration membrane was fabricated by incorporating polypyrrole-graphitic carbon nitride (PPy@G-CN) nanocomposite photo-catalyst through interfacial polymerization for water decontamination and desalination applications. An ultrafiltration polysulfone/polyethylene terephthalate (PSf/PET) membrane support was prepared through phase inversion and a hyper-cross-linked PPy@G-CN/polyamide active layer was fabricated on the PSf/PET by using N,N-bis(2-aminoethyl)-1,3-propanediamine (as an aqueous amine) and terephthaloyl chloride (TPC as a non-aqueous solution) while different amounts of PPy@G-CN nanocomposite photo-catalyst were homogeneously dispersed in aqueous amine solution before interfacial polymerization reaction and three fabricated membranes were named as x%-PPy@G-CN/HCPAMs. Out of the three fabricated membranes, 0.10%-PPy@G-CN/HCPAM was found to be the best performing membrane in terms of flux and % rejection. The maximum water flux of the membrane was found to be 78.57 L m−2 h−1 at 25 bars with rejection of Eriochrom Black T (EBT) approaching 99.90% at 20 bar. Moreover, the 0.10%-PPy@G-CN/HCPAM also showed a remarkable rejection of 79.58% and 72.88% for MgSO4 and NaCl, respectively. The 0.10%-PPy@G-CN/HCPAM showed exceptionally high photocatalytic self-cleaning as all of the organic fouling (coloration) due to EBT was removed under simulated solar light irradiation for 1 h leading to photocatalytic degradation of EBT. The 0.10%-PPy@G-CN/HCPAM membrane remained physically intact even after elongated exposure to light source.

Synthesis and characterization of new aromatic copoly(ether amide)s bearing 4-trifluoromethylphenyl-2,6-diphenylpyridyl moieties in the main chain

A series of new aromatic fluorinated copoly(ether amide)s containing 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl moiety with high molecular weight were prepared by a low-temperature solution polycondensation of terephthaloyl chloride with 4-(4-trifluoromethylphenyl)-2,6-bis(4-aminophenyl)pyridine and 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene with various mole ratios of the two monomers ranged from 20/80 to 80/20. All polymers were amorphous and soluble in common organic solvents such as N-methyl-2-pyrrolidone, N,N-dimethylacetamide and tetrahydrofuran at room temperature or upon heating at 70oC, and could be solution cast into transparent, tough, and flexible films with tensile strengths of 66.9–80.2 MPa, tensile moduli of 1.84–2.03 GPa, and elongations at break of 11.8–20.7%. These new polyamides displayed good thermal stability with gradually increasing of glass temperatures of 259–285oC as an increase of the 4-(4-trifluoromethylphenyl)-2,6-diphenylpyridyl component, the temperature at 10% weight loss of 476–505oC, and the residue of 55–61% at 750oC in nitrogen. They also exhibited low dielectric constants of 3.11–3.38 (1 MHz), low moisture absorption in the range of 1.43–1.75%, and high transparency with an UV–vis absorption cut-off wavelength in the 350–368 nm range.

Fabrication of supported carbide-derived-carbon membrane by two phases of interfacial polymerization for oil/water separation

As recovery of clean and potable water from oil contaminated produced water lies at the heart of petroleum industry, various membranes have been developed to address this challenge. Given the salient features of high thermal and chemical stabilities, ceramic membranes possess huge potential for recovering potable water from produced water. A new CDC/PA@Ceramic membrane (carbide-derived carbon/polyamide on Al2O3 ceramic support) was fabricated by depositing carbide derived carbon (CDC) on alumina support through two phases of interfacial polymerization using piperazine and 3,5-diaminobenzoic acid crosslinked through terephthaloyl chloride. The merits of the fabricated membrane were thoroughly characterized by several characterization techniques including Field emission scanning electron microscopy, Energy-dispersive X-ray spectroscopy, Elemental mapping, Powder X-ray diffraction and Attenuated total reflectance Fourier transform infra-red spectroscopy. The CDC/PA@Ceramic membrane showed promising performance in terms of permeate flux and separation efficiency for oil/water emulsion. The separation efficiency remained >96% for all studied emulsion-concentrations (250 ppm, 125 ppm and 67.5 ppm). The highest separation efficiency was >98% with a feed concentration of 67.5 ppm of oil/water emulsion. The highest pure water permeate flux reached 250 L/m2.h at 4 bar. The long-term stability test showed that the CDC/PA@Ceramic membrane remained stable for elongated time of 720 min with constant separation efficiency of >96% and permeate flux of 58 L/m2.h at 2 bars. All results were validated by visual inspection, fluorescence spectrophotometry and optical microscopy of the feed and permeate throughout the membrane performance tests. The CDC/PA@Ceramic membrane can be a potential candidate for recovering precious water from the waste produced water.

Design and fabrication of fouling resistant cross-linked polyamide thin film composite nanofiltration membrane consisting of an aliphatic triamine and terephthaloyl chloride for water desalting applications

Although a lot of polyamide thin film composite nanofiltration (TFC-NF) membranes have been developed but organic and biofouling are affecting the performance and lifespan of such membranes. Hence, the development of new and efficient polyamide membrane with a great potential against fouling is desperately needed. A new polyamide TFC-NF membrane was fabricated by reacting a linear aliphatic diethylene triamine (DETA) and linear cross-linker terephthaloyl chloride (TPC) through interfacial polymerization on ultrafiltration porous support. The resulting membrane namely Polyamide@PSf/PET was further treated with 15% hydrofluoric acid (HF) for 1 week. Membranes were extensively characterized by XPS, AFM, Zeta-potential, FESEM, FTIR, EDX, Elemental mapping and Contact angle. The HF treated Polyamide@PSf/PET showed superior performance in terms of pure water flux and rejection of tested salts and flux recovery. The highest observed water flux was 48 LMH at 24 bars while the rejection of MgSO4 reached to > 95%. HF treated Polyamide@PSf/PET membrane showed greater flux recovery of 86.4% compared to Polyamide@PSf/PET which showed a flux recovery of 84.5%. The HF treated membrane showed lower tendency towards biofouling. The bacteriostatic studies revealed that the HF treated Polyamide@PSf/PET membrane inhibited S. aureus growth by 70.7%.