Synthesis and Performance Evaluation of CO2/N2 Switchable Tertiary Amine Gemini Surfactant

A type of switchable tertiary amine Gemini surfactant, N,N′‐di(N,N‐dimethyl propylamine)‐N,N′‐didodecyl ethylenediamine, was synthesized by two substitution reactions with 3‐chloro‐1‐(N,N‐dimethyl) propylamine, bromododecane and ethylene diamine as main raw materials. The structure of the product was characterized by FTIR and ¹H‐NMR. We also investigated the surface tension when CO₂ was bubbled in different concentrations of surfactant solution and the influence of different CO₂ volumes on surface tension under a constant surfactant concentration. Finally the surface tension curve and the related parameters were acquired by surface tension measurements. The experimental results showed that the structure of the synthesized compounds were in conformity with the expected structure of the surfactant, and displayed a better surface activity after bubbling CO₂. The critical micelle concentration (CMC) surface tension at CMC (γ_cmc) pC₂₀ (negative logarithm of the surfactant's molar concentration C₂₀, required to reduce the surface tension by 20 mN/m) surface excess (Γ_max) at air/solution interface and the minimum area per surfactant molecule at the air/solution interface (A_min) were determined. Results indicate that the target product had good surface activity after bubbling CO₂.     

Recovery and Recycling of CO2/N2‐Switchable Anionic Surfactants in Emulsions

To develop a mild, effective, and clean strategy for recovery and recycling of anionic surfactants in CO₂/N₂‐switchable emulsions, a CO₂/N₂‐switchable anionic surfactant, which is a combination of dodecyl seleninic acid (DSA) and N,N,N′,N′‐tetramethyl‐1,2‐ethylenediamine (TMEDA), here referred to as DSA–TMEDA, was used to stabilize an oil‐in‐water (O/W) emulsion. Upon stimulation with CO₂, DSA–TMEDA was switched off to form insoluble DSA and the water‐soluble TMEDA bicarbonate. Upon N₂ bubbling and heating, the OFF state of DSA–TMEDA was restored to the surfactant of DSA–TMEDA. In this manner, O/W emulsions stabilized by DSA–TMEDA can be switched reversibly between demulsification (phase separation) and re‐emulsification (recovered emulsion) by triggering with CO₂/N₂ over ten times. After breakage of the emulsion, nearly all of the OFF state surfactant could be separated conveniently away from the oil phase, thus facilitating recovery and recycling of the surfactant afterward in emulsifying oil. No obvious adverse changes in the dispersed oil particles size and the relative stability of the regenerated emulsions were observed over five cycles, and the surfactant loss can be neglected during the recycling.     

Synthesis of switchable amphipathic molecules triggered by CO2 through carbonyl‐amine condensation

Five long‐chain alkyl amidines were synthesized by condensation of N,N‐dimethylacetamide with octylamine, decylamine, dodecylamine, tetradecylamine, and hexadecylamine, respectively. Synthesis conditions including solvent, pH, temperature, and ratio of reactants were studied. The series of long‐chain alkyl amidine compounds reacted with dry ice to produce amidinium bicarbonates cationic amphipathic molecules. The critical micelle concentration (cmc) and surface tension at cmc (γ_cmc) measured by drop volume method show that these amphipathic molecules have excellent surface activity. The changes of cationic content measured by two‐phase titration and conductivity before and after bubbling CO₂, show different properties between amidines and amidinium bicarbonates cationic amphipathic molecules. The switchable function of the amidinium bicarbonate cationic amphipathic molecule in emulsification and demulsification was studied. Practical applications : Our innovative work is synthesizing switchable amphipathic molecules, N′‐alkyl‐N,N‐dimethylacetamidines, by carbonyl‐amine condensation. Compared with a former way of synthesis, our work shows great potential advantages in industrial application. Our synthesis route is simpler with higher yield and is carried out at ambient temperature. Moreover, the products are environmentally friendly. Compared with traditional amphipathic molecules, our products, N′‐alkyl‐N,N‐dimethylacetamidines, show good switchable properties, which can be switched on and off, trigged by CO₂.This means these products can be reused for several times, which is significant for environmental protection.     

CO2‐Switchable Oil/Water Emulsion for Pipeline Transport of Heavy Oil

By mixing an aqueous solution of tertiary amine, N,N‐dimethylethanolamine (DMEA), with naphthenic acid (RCOOH) derived from heavy oil, a CO₂ switchable zwitterionic surfactant (RCOO^?DMEAH⁺) aqueous system was constructed. The CO₂ switchability of this zwitterionic surfactant was confirmed by visual inspection, pH measurements, and conductivity tests, i.e., the RCOO^?DMEAH⁺ decomposed into RCOOH, DMEAH⁺ and HCO₃^? after bubbling CO₂ through but switched back to its original state by subsequent bubbling N₂ through at 80 °C to remove the CO₂. The interfacial tension tests of heavy oil in DMEA aqueous solutions indicated that the solution containing 0.5 wt% of DMEA and 0.2 wt% of NaCl resulted in the lowest interfacial tension. The O/W emulsion formed when aqueous solutions of DMEA were used to emulsify heavy oil exhibited the best performance when the oil/water volume ratio, DMEA concentration, and NaCl concentration were 65:35, 0.5 and 0.2 wt%, respectively. The feasibility of pipeline transport of the O/W heavy oil emulsion was evaluated. The results illustrated that the demulsification of the O/W emulsion after transport could be easily realized by bubbling CO₂ through. Although demulsification efficiency still needs to be improved, the recycling of the aqueous phase after demulsification by removal of CO₂ looks promising.     

Temperature‐responsive alginate‐g‐poly(N,N‐diethylacrylamide) copolymer: Synthesis,characterization, and swelling behavior

Temperature‐responsive polymers have recently gained importance due to their applications in drug delivery. Herein, temperature‐responsive graft copolymer (Alg‐g‐PDEAAm) of alginate and N,N‐diethylacrylamide was synthesized by microwave‐assisted copolymerization using potassium persulfate/N,N,N′,N′‐tetramethylethylenediamine initiator system. The reaction conditions for the best grafting (331%) have been optimized by changing microwave irradiation time, temperature, N,N‐diethylacrylamide, and alginate concentrations. The spectroscopic characteristic, thermal properties, and surface morphology of the copolymers were investigated by FTIR, ¹H‐NMR, DSC/TGA, XRD, gel permeation chromatography, and SEM. Furthermore, low critical solution temperatures of Alg‐g‐PDEAAm copolymers were detected by UV spectroscopy. Swelling ratio of graft microspheres was carried out at 25, 32, and 37 °C, and microspheres were found exhibiting temperature‐responsive property. Cytotoxicity test indicated the Alg‐g‐PDEAAm copolymer and its microsphere were biocompatible. Therefore, based on the results the synthesized temperature‐responsive copolymer could be considered as a promising biomaterial. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46688.     

Effect of Polyoxyethylene Chain Length on the Physicochemical Properties of N,N‐Dimethyl‐N‐dodecyl Polyoxyethylene Amine Oxide Hybrid Surfactants (C12EOnAO,with n = 1–4)

In order to determine the structure‐performance relationship of nonionic‐zwitterionic hybrid surfactants, N,N‐dimethyl‐N‐dodecyl polyoxyethylene (n) amine oxides (C₁₂EO_nAO) with different polyoxyethylene lengths (EO_n, n = 1–4) were synthesized. For homologous C₁₂EO_nAO, it was observed that the critical micelle concentration (CMC), the maximum surface excess (Γ_m), CMC/C₂₀, and the critical micelle aggregation number (N_m,c) decreased on going from 1 to 4 in EO_n. However, there were concomitant increases in surface tension at the CMC (γ_CMC), minimum molecular cross‐sectional area (A_min), adsorption efficiency (pC₂₀), and the polarity ([I₁/I₃]_m) based on the locus of solubilization for pyrene. The values of log CMC and N_m,c decreased linearly with EO_n lengthening from 1 to 4, although the impact of each EO unit on the CMC of C₁₂EO_nAO (n = 1–4) was much smaller than that typically seen for methylene units in the hydrophobic main chains of traditional surfactants. Compared to the structurally related conventional surfactant N,N‐dimethyl‐N‐dodecyl amine oxide (C₁₂AO), C₁₂EO_nAO (n = 1–4) have smaller CMC, A_min, and CMC/C₂₀, but larger pC₂₀, Γ_m, and N_m,c with a higher [I₁/I₃]_m. This may be attributed to the moderately amphiphilic EO_n (n = 1–4) between the hydrophobic C₁₂ tail and the hydrophilic AO head group.     

Viscoelastic Surfactants with High Salt Tolerance,Fast‐Dissolving Property,and Ultralow Interfacial Tension for Chemical Flooding in Offshore Oilfields

Injected chemical flooding systems with high salinity tolerance and fast‐dissolving performance are specially required for enhancing oil recovery in offshore oilfields. In this work, a new type of viscoelastic‐surfactant (VES) solution, which meets these criteria, was prepared by simply mixing the zwitterionic surfactant N‐hexadecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propane sulfonate (HDPS) or N‐octyldecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propane sulfonate (ODPS) with anionic surfactants such as sodium dodecyl sulfate (SDS). Various properties of the surfactant system, including viscoelasticity, dissolution properties, reduction of oil/water interfacial tension (IFT), and oil‐displacement efficiency of the mixed surfactant system, have been studied systematically. A rheology study proves that at high salinity, 0.73 wt.% HDPS/SDS‐ and 0.39 wt.% ODPS/SDS‐mixed surfactant systems formed worm‐like micelles with viscosity reaching 42.3 and 23.8 mPa s at a shear rate of 6 s^?1, respectively. Additionally, the HDPS/SDS and ODPS/SDS surfactant mixtures also exhibit a fast‐dissolving property (dissolution time <25 min) in brine. More importantly, those surfactant mixtures can significantly reduce the IFT of oil–water interfaces. As an example, the minimum of dynamic‐IFT (IFT_min) could reach 1.17 × 10^?2 mN m^?1 between the Bohai Oilfield crude oil and 0.39 wt.% ODPS/SDS solution. Another interesting finding is that polyelectrolytes such as sodium of polyepoxysuccinic acid can be used as a regulator for adjusting IFT_min to an ultralow level (<10^?2 mN m^?1). Taking advantage of the mobility control and reducing the oil/water IFT of those surfactant mixtures, the VES flooding demonstrates excellent oil‐displacement efficiency, which is close to that of polymer/surfactant flooding or polymer/surfactant/alkali flooding. Our work provides a new type of VES flooding system with excellent performances for chemical flooding in offshore oilfields.     

A Zwitterionic Surfactant Bearing Unsaturated Tail for Enhanced Oil Recovery in High‐Temperature High‐Salinity Reservoirs

High‐temperature/high‐salinity (HTHS) reservoirs contain a significant fraction of the world's remaining oil in place and are potential candidates for enhanced oil recovery (EOR). Selection of suitable surfactants for such reservoirs is a challenging task. In this work, two synthesized zwitterionic surfactants bearing a saturated and an unsaturated tail, namely 3‐(N‐stearamidopropyl‐N,N‐dimethyl ammonium) propanesulfonate and 3‐(N‐oleamidopropyl‐N,N‐dimethyl ammonium) propanesulfonate, respectively, were evaluated. The surfactant with the unsaturated tail showed excellent solubility in synthetic seawater (57,643 ppm) and in formation brine (213,734 ppm). However, the unsaturated surfactant with a saturated tail showed poor solubility, and therefore it was not evaluated further. The thermal stability of the synthesized unsaturated surfactant solution in seawater was evaluated by heating the solution at 90 °C in a sealed aging tube for 2 weeks. The thermal stability of the unsaturated surfactant was confirmed by FTIR and NMR analysis of the aged samples at such harsh conditions. The critical micelle concentration (CMC) of the synthesized unsaturated surfactant in seawater was 1.02 × 10^?4 mol L^?1, while the surface tension at CMC was 30 mN m^?1. The synthesized unsaturated surfactant was able to reduce the oil–water interfacial tension to ~10^?1 mN m^?1 at different conditions. A commercial copolymer of acrylamide and 2‐acrylamido‐2‐methylpropane sulfonic acid (AM‐AMPS) was tested for EOR applications in HTHS conditions. The addition of the synthesized unsaturated surfactant to the AM‐AMPS copolymer increased the viscosity of the system. The increase in oil recovery by injecting the unsaturated surfactant solution and the surfactant–polymer mixture in solution was 8 and 21%, respectively. The excellent properties of the synthesized unsaturated surfactant show that surfactants with an unsaturated tail can be an excellent choice for HTHS reservoirs.     

A Novel Alkyl Sulphobetaine Gemini Surfactant Based on S‐triazine: Synthesis and Properties

A series of alkyl sulphobetaine Gemini surfactants C_n‐GSBS (n = 8, 10, 12, 14, 16) was synthesized, using aliphatic amine, cyanuric chloride, ethylenediamine, N,N′‐dimethyl‐1,3‐propyldiamine and sodium 2‐chloroethane sulfonate as main raw materials. The chemical structures were confirmed by FT‐IR, ¹H NMR and elemental analysis. The Krafft points differ markedly with different carbon chain length, for C₈‐GSBS, C₁₀‐GSBS and C₁₂‐GSBS are considered to be below 0 °C and C₁₄‐GSBS, C₁₆‐GSBS are higher than 0 °C but lower than room temperature. Surface‐active properties were studied by surface tension and electrical conductivity. Critical micelle concentrations were much lower than dodecyl sulphobetaine (BS‐12) and decreased with increasing length of the carbon chain from 8 to 16, and can reach a minimum as low as 5 × 10^?5 mol L^?1 for C₁₆‐GSBS. Effects of carbon chain length and concentration of C_n‐GSBS on crude oil emulsion stability were also investigated and discussed.     

Laboratory study of an anti‐temperature and salt‐resistance surfactant‐polymer binary combinational flooding as EOR chemical

Experimental studies were conducted to enhance the oil recovery by a surfactant‐polymer binary combinational flooding system. The surfactant‐polymer binary combinational flooding was obtained by mixing the surfactants with the poly(AM‐NVP‐AS)‐1 which was an anti‐temperature and salt‐resistance tercopolymer and successfully synthesized via free radical polymerization using acrylamide (AM), N‐vinyl pyrrolidone (NVP), allyl sulfonate (AS) as raw materials. The initiator was redox system including water‐soluble azo compound (AIBA·2HCl) and sodium bisulfite (NaHSO₃). Petroleum carboxylate dodecyl dibasic carbonylic acid sodium (C12DAS) and carboxyl betaine dodecyl dimethyl betaine (C12DB) were selected in this article. Compared with the surfactant‐HPAM, the surfactant‐poly(AM‐NVP‐AS)‐1 binary combinational system showed higher apparent viscosity and lower interfacial tension at high temperature and salinity conditions as the result of a better capacity of anti‐temperature, salt‐resistance, and swept volume. The recovery could enhance over 17% based on the core flooding test under the mineralization of 10,000 mg/L at 65°C. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2014 , 131, 39984.     

Gas solubility in long‐chain imidazolium‐based ionic liquids

The gas solubility in 1‐dodecyl‐3‐methylimidazolium [C₁₂MIM] based ionic liquids (ILs) was measured at temperatures (333.2, 353.2, and 373.2) K and pressures up to 60 bar for the first time. The popular UNIFAC‐Lei model was successfully extended to long‐chain imidazolium‐based IL and gas (CO₂, CO, and H₂) systems. The free volume theory was used to explain the gas solubility and selectivity in imidazolium‐based ILs by calculating the fractional free volume and free volume by the COSMO‐RS model. Furthermore, the excess enthalpy of gas‐IL system was concerned to provide new insights into temperature dependency of gas (CO₂, CO, and H₂) solubility in ILs. The experimental data, calculation, and theoretical analysis presented in this work are important in gas separations with ILs or supported ionic liquid membranes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 1792–1798, 2017     

Iron‐Catalyzed Oxidative Mono‐ and Bis‐Phosphonation of N,N‐Dialkylanilines

The dehydrogenative α‐phosphonation of substituted N,N‐dialkylanilines by dialkyl H‐phosphonates was achieved under mild conditions by using environmentally benign iron(II) chloride as catalyst and tert‐butyl hydroperoxide as oxidant. The reaction proceeded in the presence of electron‐donating (methoxy, methyl, benzyl) and electron‐withdrawing ring‐substitutents (bromo, carbonyl, carboxyl, m‐nitro) in moderate to good yields. The X‐ray crystal structure of N‐(5,5‐dimethyl‐2‐oxo‐2λ⁵‐[1,3,2]dioxaphosphinan‐2‐yl‐methyl)‐N‐methyl‐p‐toluidine was determined. Bis‐(4‐(dimethylamino)phenyl)methane and bis‐4,4′‐(dimethylamino)benzophenone underwent bisphosphonation selectively by respective monophosphonation at the remote dimethylamino groups. Furthermore, the use of excess dialkyl H‐phosphonate and oxidant allowed us to functionalize both methyl groups of N(CH₃)₂ in N,N‐dimethyl‐p‐toluidine and N,N‐dimethylaminomesidine, respectively, to obtain α,α′‐bisphosphonatoamines in high yield.     

Mixed matrix membranes of Pebax1657 loaded with iron benzene‐1,3,5‐tricarboxylate for gas separation

Mixed matrix membranes offer major advantages in gas separation processes due to desirable properties found in both organic and inorganic membranes. In this study, a novel mixed matrix membrane was prepared for such application by incorporating iron benzene‐1,3,5‐tricarboxylate (Fe‐BTC) into the poly(amide‐6‐b‐ethylene oxide) (Pebax1657) polymer. Membranes with various loadings of 5, 10, and 20 wt% Fe‐BTC in the polymer matrix were fabricated to investigate the effect of filler loading on the membrane performance. Membranes, prepared by solution‐casting were characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared, X‐ray diffraction, and tensile test. Pure gas separation of CO₂, CH₄, and N₂ and ideal gas selectivity of CO₂/CH₄ and CO₂/N₂ were performed and permeation tests were carried out under 4, 8, and 12 bar pressures. Results show that adding Fe‐BTC into the Pebax1657 matrix improved both permeability and selectivity of the filled membranes. For instance, 10 wt% loading of Fe‐BTC into the Pebax1657 matrix led to CO₂ permeability increase of 49% as well as CO₂/CH₄ and CO₂/N₂ selectivities enhancements of about 36% and 16%, respectively. POLYM. COMPOS., 38:1363–1370, 2017. © 2015 Society of Plastics Engineers     

Use of a CO2‐switchable hydrophobic associating polymer to enhance viscosity–response

A series of copolymers, poly(acrylamide)‐co‐poly(N,N‐dimethylaminoethyl methacrylate)‐co‐poly(N‐cetyl DMAEMA) (abbreviation PDAMCn), was synthesized with different monomer ratios. The resulting copolymer solution shows pronounced viscosity–response property which is CO₂‐triggered and N₂‐enabled. Electrical conductivity experiment shows that tertiary amine group on DMAEMA experiences a protonate and deprotonate transition upon CO₂ addition and its removal. In addition, different incorporation rates of DMAEMA leads to two kinds of morphological change in the presence of CO₂ and thus induces different rheological behaviors. PDAMCn incorporating longer hydrophobic monomer (C₁₈DM) show more pronounced initial viscosity and higher critical stress required to cause network deformation, which consequently enhances the viscosity–response property of the solution. The addition of NaCl could also tune the viscosity of PDAMCn solution. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41468.     

Synthesis and Properties of N‐Alkyl–N,N‐Dimethyl‐N‐(o‐Hydroxymethyl)Benzylammonium Chlorides

A series of N‐alkyl–N,N‐dimethyl‐N‐(o‐hydroxymethyl)benzylammonium chlorides surfactants (DHBA‐m) were synthesized using o‐chloromethylbenzyl alcohol and N‐alkyl–N,N‐dimethyl tertiary amine as raw materials. The structure of the products was confirmed by FT‐IR, ¹H NMR, ¹³C NMR and MS. DHBA‐m surfactants exhibit low Krafft points and high surface activities. The process of micellization of DHBA‐m is spontaneous, exothermic, and entropy‐driven. The hydroxymethyl substitution increases hydrophobicity of DHBA‐m, thus making micellization more favorable compared with that of N‐dodecyl–N,N‐dimethyl‐N‐benzylammonium chlorides (DDBAC‐m). The bactericidal activity of DHBA‐m is stronger on E. coli than that of DDBAC‐12, and DHBA‐16 shows strong bactericidal activity on Salmonella, S. aureus, and Streptococcus.     

Fabrication of Homogenous Polymer‐Zeolite Nanocomposites as Mixed‐Matrix Membranes for Gas Separation

Interfacial void‐free mixed‐matrix membranes (MMMs) of polyimide (PI)/zeolite were developed using 13X and Linde type A nano‐zeolites and tested for gas separation purposes. Fabrication of a void‐free polymer‐zeolite interface was verified by the decreasing permeability developed by the MMMs for the examined gases, in comparison to the pure PI membrane. The molecular sieving effect introduced by zeolite 13X improved the CO₂/N₂ and CO₂/CH₄ selectivity of the MMMs. Separation tests indicated that the manufactured nanocomposite membrane with 30 % loading of 13X had the highest permselectivity for the gas pairs CO₂/CH₄ and CO₂/N₂ at the three examined feed pressures of 4, 8 and 12 atm.     

Synthesis and characterization of novel wholly para‐oriented aromatic polyamide‐hydrazides containing sulfone‐ether linkages

Four novel wholly para‐oriented aromatic polyamide‐hydrazides containing flexibilizing sulfone‐ether linkages in their main chains have been synthesized from 4‐amino‐3‐hydroxy benzhydrazide (4A3HBH) with either 4,4′‐sulfonyldibenzoyl chloride (SDBC), 4,4′‐[sulfonylbis(1,4‐phenylene)dioxy]dibenzoyl chloride (SODBC), 4,4′‐[sulfonylbis(2,6‐dimethyl‐1,4‐phenylene)dioxy]dibenzoyl chloride (4MeSODBC), or 4,4′‐(1,4‐phenylenedioxy)dibenzoyl chloride (ODBC) via a low‐temperature solution polycondensation reaction. A polyamide‐hydrazide without the flexibilizing linkages is also investigated for comparison. It was synthesized from 4A3HBH and terephthaloyl chloride (TCl) by the same synthetic route. The intrinsic viscosities of the polymer ranged from 2.85 to 4.83 dL g^?1 in N,N‐dimethyl acetamide (DMAc) at 30°C and decreased with introducing the flexibilizing linkages into the polymer. All the polymers were soluble in DMAc, N,N‐dimethyl formamide (DMF), and N‐methyl‐2‐pyrrolidone (NMP), and their solutions could be cast into films with good mechanical strengths. Further, they exhibited a great affinity to water sorption. Their solubility and hydrophilicity increased remarkably by introducing the flexibilizing linkages. The polymers could be thermally cyclodehydrated into the corresponding poly(1,3,4‐oxadiazolyl‐benzoxazoles) approximately in the region of 295–470°C either in nitrogen or in air atmospheres. The flexibilizing linkages improve the solubility of the resulting poly(1,3,4‐oxadiazolyl‐benzoxazoles) when compared with poly(1,3,4‐oxadiazolyl‐benzoxazoles) free from these linkages. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Untersuchung der CO2‐Absorptionskinetik in wässrigen Lösungen von N,N‐Diethylethanolanmin und N‐Ethylethanolamin

N‐Ethylethanolamine (EEA) and N,N‐diethylethanolamine (DEEA) represent promising alkanolamines for CO₂ removal from gaseous streams, as they can be prepared from renewable resources. In this work, the reaction rate constant for the reaction between CO₂ and EEA and the liquid‐side mass transfer coefficient were determined from the absorption rate measurements in a blend comprising DEEA, EEA and H₂O. A stirred‐cell reactor was applied for the absorption studies, whereas a zwitterion mechanism for EEA and a base‐catalyzed hydration mechanism for DEEA were used to describe the reaction kinetics.     

Preparation of poly(ether‐block‐amide)/poly(amide‐co‐poly(propylene glycol)) random copolymer blend membranes for CO2/N2 separation

A series of poly(amide‐co‐poly(propylene glycol)) (PA‐PPG) random copolymers with different content of PPG were designed by polycondensation reaction. These random copolymers were blended up to 60% with commercially available Pebax 2533. The blend membranes were characterized by Fourier‐transform infrared (FTIR) spectroscopy, X‐ray diffraction (XRD), scanning electron microscope (SEM). Gas permeation properties of these blend membranes were investigated using five single‐gases (CO₂, H₂, O₂, CH₄, and N₂) at different temperature of 25–55°C and 1.0 atm. The impacts of content of PA‐PPG with different PPG content and operating temperature on CO₂ separation properties of Pebax/PA‐PPG blend membranes were studied. The results showed that CO₂ permeability gradually increased with the increasing operating temperature, whereas CO₂ permeability gradually decreased with the increase in content of PA‐PPG. CO₂/N₂ selectivity gradually increased with the increase in content of PA‐PPG. In particular, Pebax/PA‐PPG (50)–60% displayed excellent CO₂ and O₂ separation properties (P_CO2 = 79.7 Barrer and P_O2 = 13.6 Barrer, CO₂/N₂ = 34.7 and O₂/N₂ = 5.9) at 25°C and 1.0 atm. POLYM. ENG. SCI., 59:E14–E23, 2019. © 2018 Society of Plastics Engineers     

New synthetic method for soluble starlike C60‐bonding polymers

Novel starlike C₆₀‐bonding polymers were synthesized by using the iniferter technique. The fullerene C₆₀ with pendent N,N‐diethyldithiocarbamate groups (C₆₀–SR) was used as polyfunctional photoiniferter. The effects of UV‐irradiation time and ambient temperature on the molecular weight of polymer were investigated. The photopolymerization with C₆₀–SR proceeded via a living‐radical mechanism, and gave soluble polyfunctional polymers (photoiniferters). Multiple polymer arms were attached to the C₆₀ core and the polymers obtained by C₆₀–SR could also be used as excellent crosslinking agents. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1286–1290, 2001