Oxyethylene Units Research Articles

Electrolytes from Alkoxyalkyl-substituted Imidazolium ionic liquids. Synthesis, characterization, properties and cell performance in LiFePO4 half-cells

Electrolytes based on lithium bis(trifluoromethane)sulfonimide (LiTFSI) salt and alkoxyalkyl-substituted imidazolium ionic liquids (ILs) have been studied. We have synthesized three different 1-alkoxyalkyl-3-methylimidazolium TFSI salts with different chain lengths (from 4 to 10 atoms) and with one to three oxygen atoms at position 1- of the imidazole ring. Both the neat ILs as well as the cognate lithium doped electrolytes have been structurally and physicochemically characterized and electrochemically evaluated.Thermal analyses indicate that the glass transition temperature of the electrolytes is displaced to higher temperatures than those of the corresponding neat ILs, being also higher (more positive) upon increasing the number of oxyethylene units. On the other hand, all 1 M LiTFSI doped synthesized electrolytes are thermally stable up to 300 °C.Raman spectroscopy results indicate that the fraction of TFSI anions coordinated to lithium ion decreases on increasing the number of alkoxy units. This finding implies that there is more “free” lithium ion available to link to the ethereal oxygen of the side chain of the imidazolium ring system. This fact influences the ionic conductivity of the neat ILs and their cognate electrolytes.The electrochemical properties —namely high room temperature conductivities as well as wide electrochemical stability windows— indicate that these materials are promising electrolytes for lithium-ion batteries (LIBs). Lithium half-cells using LiFePO4 (LFP) olivine have been assembled in order to assess the electrochemical performance by means of both cyclic voltammetry and galvanostatic charge/discharge tests. Overall, we have found that the electrochemical performance of these cells is better than that reported 1 M LiTFSI [Pyr14][TFSI], a common electrolyte in LIBs. The generated half-cell from the 1-alkoxyalkyl-3-methylimidazolium TFSI salts possess a high capacity up to 145 mAh∙g−1 at a current of 2C.The results reported herein show a striking relationship between structure and properties.

Biodegradable Hydrogenated Dimer Acid-Based Plasticizers for PLA with Excellent Plasticization, Thermal Stability and Gas Resistance.

The use of vegetable oil-dervied plasticizers to enhance the flexibility of polylactic acid (PLA) has received much attention due to their renewability, inexpensiveness and biodegradation. However, the double bonds in vegetable oil-based plasticizers limit their compatibility with PLA, resulting in PLA-derived products with reduced flexibility. Herein, we examined soybean oil-derived hydrogenated dimer acid-based polyethylene glycol methyl ether esters (HDA-2n, 2n = 2, 4, 6 or 8, referring to the ethoxy units) developed via the direct esterification of saturated hydrogenated dimer acid and polyethylene glycol monomethyl ethers. The resulting HDA-2n was first used as a plasticizer for PLA, and the effects of the ethoxy units in HDA-2n on the overall performance of the plasticized PLA were systematically investigated. The results showed that, compared with PLA blended with dioctyl terephthalate (DOTP), the PLA plasticized by HDA-8 with the maximum number of ethoxy units (PLA/HDA-8) exhibited better low-temperature resistance (40.1 °C vs. 15.3 °C), thermal stability (246.8 °C vs. 327.6 °C) and gas barrier properties. Additionally, the biodegradation results showed that HDA-8 could be biodegraded by directly burying it in soil. All results suggest that HDA-8 could be used as green alternative to the traditional petroleum-based plasticizer DOTP, which is applied in the PLA industry.

One-Pot Synthesis of Amphipathic Esters for Demulsification of Water-in-Crude Oil Emulsions.

The current work aims to synthesize new amphipathic compounds, TGHA and PGHA, and investigate their demulsification performance (DP) in water-in-crude oil emulsions. Their chemical structures, thermal stability, interfacial activity, and micelle formation were investigated by different techniques. The bottle test method was used to investigate the effect of demulsifier concentration, water content, temperature, and demulsification time (DT) on the DP of TGHA and PGHA compared to a commercial demulsifier (CD). The results indicated that these parameters have a noticeable impact on the DP of TGHA and PGHA. The results also showed that TGHA exhibited higher DP than PGHA at all investigated parameters, which could be explained by increasing its hydrophobicity due to lower oxyethylene units in its structure than PGHA. An increase in these units means increased hydrophilicity, which led to obstruction of PGHA molecule diffusion in crude oil as a continuous phase. Moreover, TGHA gave a comparable DP with CD, as it gave a higher DP and shorter DT than CD at a higher water content (50%), while the latter achieved the highest DP and the shortest DT at a low water content (10%).

Towards understanding the crystallization of photosystem II: influence of poly(ethylene glycol) of various molecular sizes on the micelle formation of alkyl maltosides.

The influence of poly(ethylene glycol) (PEG) polymers H-(O-CH2-CH2)p-OH with different average molecular sizes on the micelle formation of n-alkyl-β-D-maltoside detergents with the number of carbon atoms in the alkyl chain ranging from to is investigated with the aim to learn more about the detergent behavior under conditions suitable for the crystallization of the photosynthetic pigment-protein complex photosystem II. PEG is shown to increase the critical micelle concentration (CMC) of all three detergents in the crystallization buffer in a way that the free energy of micelle formation increases linearly with the concentration of oxyethylene units (O-CH2-CH2) irrespective of the actual molecular weight of the polymer. The CMC shift is modeled by assuming for simplicity that it is dominated by the interaction between PEG and detergent monomers and is interpreted in terms of an increase of the transfer free energy of a methylene group of the alkyl chain by 0.2kJmol-1 per 1mol L-1 increase of the concentration of oxyethylene units at 298K. Implications of this effect for the solubilization and crystallization of protein-detergent complexes as well as detergent extraction from crystals are discussed.

Volumetric properties of three nonylphenol ethoxylated nonionic surfactant mixtures with methanol: Experimental study and modeling with Tammann-Tait and PC-SAFT equation of state

Although physicochemical properties are essential for production and equipment design in oil and gas industries, there is still a lack of data for some systems because of hazardous temperature and pressure conditions. This work provides a volumetric behavior study of three different mixtures composed of nonylphenol ethoxylated nonionic surfactant (IGEPAL CO-520, CO-630, and CO-720) + methanol in the entire mole fraction composition range for temperatures from 313.15 K to 413.15 K and pressures up to 100.0 MPa. These systems behave as a regular liquid, with a volume contraction predominance. It was observed that for high methanol molar content, there is an increase in the cohesive forces because of the ethoxylated chain increases in oxyethylene units. Nevertheless, it was observed that the hydrogen bonds between ether oxygens and hydroxyl hydrogens decrease by increasing temperature, as given by internal pressure data and PC-SAFT modeling. Besides, a new set of parameters for the PC-SAFT equation of state is provided to calculate volumetric and second-order derivative properties.

Chiral hybrid aza-oxa-terpene-based macrocycles as selective extractants for Pd(II) and Au(III)

A series of novel hybride chiral macrocyclic compounds is described. The macrocyclic core of the new compounds is decorated with monoterpene fragments and includes 2 imine nitrogens and 2 tertiary amine nitrogens of the N,N-piperazine linkage as well as several repeating ethyleneoxy units resembling those of crown ethers. The macrocyclic compounds are prepared in moderate preparative yield (16–31%) upon treatment of a mixture of bis(α-amine oximes) and α,ω-dichloro derivatives of tri-, tetra- and hexa-ethylene glycol with sodium methylsulfinylmethylide. Chemical structure of the new macrocycles was established by a complex of spectroscopic techniques and X-ray analysis. The new macrocyclic compounds demonstrate remarkable selectivity with respect to Pd(II) and Au(III) and are able to efficiently extract these metals from acidic media containing a complex mixture of alkali metals, 3d-elements and noble metals. The features of conformational behavior, the ability to form complexes and the selectivity of extraction were studied using quantum chemical calculations at the DFT level. Based on the data obtained, a consistent scheme has been formulated to explain the features of extraction and the extraction selectivity of individual macrocycles.

A feasible strategy for depressant-free flotation separation of siderite from magnesiohornblende using a highly selective collector

At present, efficient separation of siderite from Mg-Fe-Al-bearing silicate minerals, especially magnesiohornblende, by froth flotation using conventional collectors is difficult because they have similar surface properties. In this work, polyoxyethylenated laurylamine with five oxyethylene units (POE-5 laurylamine) was used as a magnesiohornblende collector for rejecting magnesiohornblende from siderite effectively during reverse flotation. Batch flotation tests illustrated that POE-5 laurylamine exhibited an outstanding collecting capacity and a high selectivity for the magnesiohornblende flotation rather than the siderite flotation. Much better floatability of magnesiohornblende than siderite was attributed to the larger amounts of POE-5 laurylamine adsorbed onto magnesiohornblende, as demonstrated by XPS results. FTIR and zeta potential measurements further revealed that the combination of hydrogen bonding and electrostatic attraction caused POE-5 laurylamine to strongly attach on the surface of magnesiohornblende compared to siderite, which favored the selective flotation of magnesiohornblende. Consequently, the efficient depressant-free flotation separation of siderite and magnesiohornblende was realized with 0.30 mM POE-5 laurylamine at pH 6.35, in which 92.88% of magnesiohornblende was effectively removed, combined with a high siderite recovery of 95.44% in the flotation concentrate. Therefore, POE-5 laurylamine can be chosen as a potential collector for efficiently recovering siderite from magnesiohornblende during reverse flotation.

Synthesis and Bioevaluation of 2-Styrylquinoxaline Derivatives as Tau-PET Tracers.

This study focused on designing and evaluating Tau-PET tracers for noninvasive positron emission computed tomography (PET) imaging of neurofibrillary tangles (NFTs), a hallmark pathology of Alzheimer's disease (AD). The tracers were synthesized with a 2-styrylquinoxaline scaffold and varying lengths of FPEG chains. The compound [18F]15, which had two ethoxy units, showed high affinity for recombinant K18-Tau aggregates (Ki = 41.48 nM) and the highest selectivity versus Aβ1-42 aggregates (8.83-fold). In vitro autoradiography and fluorescent staining profiles further validated the binding of [18F]15 or 15 toward NFTs in brain sections from AD patients and Tau-transgenic mice. In normal ICR mice, [18F]15 exhibited an ideal initial brain uptake (11.21% ID/g at 2 min) and moderate washout ratio (2.29), and micro-PET studies in rats confirmed its ability to penetrate the blood-brain barrier with the peak SUV value of 1.94 in the cortex. These results suggest that [18F]15 has the potential to be developed into a useful Tau-PET tracer for early AD diagnosis and evaluation of anti-Tau therapeutics.

Physico-chemical characterization of Synperonic™ 91/5 self-assembly behaviour in water

We studied the self-assembled aggregates of Synperonic™ 91/5 (SYN) in water solution. This surfactant presents the peculiarity of having an odd number of aliphatic carbons, with a tail composed of C9H19 and C11H23, and the headgroup having an average of 5 ethoxy units. While the general family of CiEOj nonionic surfactants has been widely studied, there is little knowledge for the case of surfactants with odd-number carbons. For this reason, we carried out an in depth physico-chemical characterization of water solutions containing SYN in the wide range of concentration from 2 % to 50 % (i.e. 0.05–1.4 M), considering that high concentrated systems are relevant for industrial applications. This class of surfactants is also interesting as remediation agent since they can incorporate different polluting molecules, both polar and nonpolar, such as volatile Organic Compounds (VOCs) and Dense Non Aqueous Phase liquids (DNAPLs). The rheological and transport properties of SYN solutions were investigated through diffusion coefficients and viscosity, while shape and size of self-assemblies were determined by Dynamic Light Scattering and by Small Angle Scattering of Neutrons (SANS) and X-rays (SAXS). Results show that SYN generally behaves as other nonionic surfactants in dilute solutions, but shows some peculiarity of aggregate packing at high concentration. We recently demonstrated the efficiency of the Synperonic™ family of surfactants in solubilising trichloroethylene (TCE), in particular above a critical concentration of 0.1 M, thus being a good candidate for remediation purposes. Here, the solubility of TCE was correlated with the number and the size of micelles at different surfactant concentrations. Our work helps filling a gap in the literature about technical grade surfactants with odd-number carbons, and the results can help in assessing the performances of Synperonic™ products for technical tasks.

Novel poly(ionic liquid)s reinforced with three-dimensional electrospun fiber network as electrolyte for all solid state lithium batteries

Solid polymer electrolytes have been identified lately as the most pragmatic research area towards the development of safe and reliable lithium batteries with zero electrolyte leakage. In this work, ionene oligomers based on 1,4-Diazabicyclo [2.2.2] octane (DABCO) bearing oxyethylene spacers with varying –CH2CH2O- units and having bis (trifluoromethanesulfonyl) imide (TFSI−) counter anion were synthesized. The ionene oligomers exhibited excellent thermal stability up to 300 °C with glass transition below room temperature. Interestingly, the presence of oxyethylene linkers between the cationic moieties in the oligomer backbone significantly affected the Li+ ion coordination and ionic conductivity as explained by Raman spectroscopy and electrochemical impedance spectroscopy (EIS) studies carried out on binary mixtures of POnTFSI/LiTFSI (where ‘P’ indicates the oligomer and ‘On’ denotes the number ‘n’ of oxyethylene units in the spacer). The oxygen atoms present in the spacer backbone of the ionene can interact with the Li+ ions and prevent the formation of aggregates with the anions while the mobility of the TFSI−anions is restricted by the polar nature of the ionene backbone. Such binary mixtures were incorporated in an electrospun nanofibrous framework, to form a free-standing solid polymer electrolyte and the electrochemical performance was evaluated in a Li/LiFePO4 (LFP) battery.

All-Atom Molecular Dynamics Simulations of the Temperature Response of Poly(glycidyl ether)s with Oligooxyethylene Side Chains Terminated with Alkyl Groups.

Recently, experimental investigations of a class of temperature-responsive polymers tethered to oligooxyethylene side chains terminated with alkyl groups have been conducted. In this study, aqueous solutions of poly(glycidyl ether)s (PGE) with varying numbers of oxyethylene units, poly(methyl(oligooxyethylene)n glycidyl ether) (poly(Me(EO)nGE)), and poly(ethyl(oligooxyethylene)n glycidyl ether) (poly(Et(EO)nGE) (n = 0, 1, and 2) were investigated by all-atom molecular dynamics simulations, focusing on the thermal responses of their chain extensions, the recombination of intrapolymer and polymer-water hydrogen bonds, and water-solvation shells around the alkyl groups. No clear relationship was established between the phase-transition temperature and the polymer-chain extensions unlike the case for the coil-globule transition of poly(N-isopropylacrylamide). However, the temperature response of the first water-solvation shell around the alkyl group exhibited a notable correlation with the phase-transition temperature. In addition, the temperature at which the hydrophobic hydration shell strength around the terminal alkyl group equals the bulk water density (TCRP) was slightly lower than the cloud point temperature (TCLP) for the methyl-terminated poly(Me(EO)nGE) and slightly higher for the ethyl-terminated poly(Et(EO)nGE). It was concluded that the polymer-chain fluctuation affects the relationship between TCRP and TCLP.

A Theranostic Small-Molecule Prodrug Conjugate for Neuroendocrine Prostate Cancer.

After androgen deprivation therapy, a significant number of prostate cancer cases progress with a therapy-resistant neuroendocrine phenotype (NEPC). This represents a challenge for diagnosis and treatment. Based on our previously reported design of theranostic small-molecule prodrug conjugates (T-SMPDCs), herein we report a T-SMPDC tailored for targeted positron emission tomography (PET) imaging and chemotherapy of NEPC. The T-SMPDC is built upon a triazine core (TZ) to present three functionalities: (1) a chelating moiety (DOTA: 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) for PET imaging when labeled with 68Ga (t1/2 = 68 min) or other relevant radiometals; (2) an octreotide (Octr) that targets the somatostatin receptor 2 (SSTR2), which is overexpressed in the innervated tumor microenvironment (TME); and (3) fingolimod, FTY720-an antagonist of sphingosine kinase 1 that is an intracellular enzyme upregulated in NEPC. Polyethylene glycol (PEG) chains were incorporated via conventional conjugation methods or a click chemistry reaction forming a 1,4-disubstituted 1,2,3-triazole (Trz) linkage for the optimization of in vivo kinetics as necessary. The T-SMPDC, DOTA-PEG3-TZ(PEG4-Octr)-PEG2-Trz-PEG3-Val-Cit-pABOC-FTY720 (PEGn: PEG with n repeating ethyleneoxy units (n = 2, 3, or 4); Val: valine; Cit: citrulline; pABOC: p-amino-benzyloxycarbonyl), showed selective SSTR2 binding and mediated internalization of the molecule in SSTR2 high cells. Release of FTY720 was observed when the T-SMPDC was exposed to cathepsin B, and the released FTY720 exerted cytotoxicity in cells. In vivo PET imaging showed significantly higher accumulation (2.1 ± 0.3 %ID/g; p = 0.02) of [68Ga]Ga-DOTA-PEG3-TZ(PEG4-Octr)-PEG2-Trz-PEG3-Val-Cit-pABOC-FTY720 in SSTR2high prostate cancer xenografts than in the SSTR2low xenografts (1.5 ± 0.4 %ID/g) at 13 min post-injection (p.i.) with a rapid excretion through the kidneys. Taken together, these proof-of-concept results validate the design concept of the T-SMPDC, which may hold a great potential for targeted diagnosis and therapy of NEPC.

Imaging of KCa 3.1 Channels in Tumor Cells with PET and Small-Molecule Fluorescent Probes.

The Ca2+ activated K+ channel KCa 3.1 is overexpressed in several human tumor cell lines, e. g. clear cell renal carcinoma, prostate cancer, non-small cell lung cancer. Highly aggressive cancer cells use this ion channel for key processes of the metastatic cascade such as migration, extravasation and invasion. Therefore, small molecules, which are able to image this KCa 3.1 channel in vitro and in vivo represent valuable diagnostic and prognostic tool compounds. The [18 F]fluoroethyltriazolyl substituted senicapoc was used as positron emission tomography (PET) tracer and showed promising properties for imaging of KCa 3.1 channels in lung adenocarcinoma cells in mice. The novel senicapoc BODIPY conjugates with two F-atoms (9 a) and with a F-atom and a methoxy moiety (9 b) at the B-atom led to the characteristic punctate staining pattern resulting from labeling of single KCa 3.1 channels in A549-3R cells. This punctate pattern was completely removed by preincubation with an excess of senicapoc confirming the high specificity of KCa 3.1 labeling. Due to the methoxy moiety at the B-atom and the additional oxyethylene unit in the spacer, 9 b exhibits higher polarity, which improves solubility and handling without reduction of fluorescence quantum yield. Docking studies using a cryo-electron microscopy (EM) structure of the KCa 3.1 channel confirmed the interaction of 9 a and 9 b with a binding pocket in the channel pore.

C2-linked alkynyl poly-ethylene glycol(PEG) adenosine conjugates as water-soluble adenosine receptor agonists.

A series of 12 novel polyethylene-glycol(PEG)-alkynyl C2-adenosine(ADN) conjugates were synthesized using a robust Sonogashira coupling protocol and characterized by NMR spectroscopy and mass spectrometry analysis. The ADN-PEG conjugates showed null to moderate toxicity in murine macrophages and 12c was active against Mycobacterium aurum growth (MIC=62.5mg/L). The conjugates were not active against Mycobacterium bovis BCG. Conjugates 10b and 11b exhibited high water solubility with solubility values of 1.22 and 1.18 mg/ml, respectively, in phosphate buffer solutions at pH6.8. Further, 10b and 11b induced a significant increase in cAMP accumulation in RAW264.7 cells comparable with that induced by adenosine. Analogues 10c, 11c and 12c were docked to the A1 , A2A , A2B and A3 adenosine receptors (ARs) using crystal-structures and homology models. ADN-PEG-conjugates bearing chains with up to five ethyleneoxy units could be well accommodated within the binding sites of A1 , A2A and A3 ARs. Docking studies showed that compound 10b and 11b were the best A2A receptor binders of the series, whereas 12c was the best binder for A1 AR. In summary, introduction of hydrophilic PEG substituents at the C2 of adenine ring significantly improved water solubility and did not affect AR binding properties of the ADN-PEG conjugates.

Bio-inspired design of electrospun poly(acrylonitrile) and novel ionene based nanofibrous mats as highly flexible solid state polymer electrolyte for lithium batteries

All-solid-state polymer electrolytes (ASSPEs) have significant importance in the development of rechargeable lithium batteries with superior safety. Herein, a unique ionene oligomer is synthesized from 1,4-Diazabicyclo [2.2.2] octane (DABCO) and diethylene glycol bis(2-chloroethyl)ether having bis(trifluoromethanesulfonyl) imide (TFSI−) as the anion (PO3TFSI, where, ‘P’ indicates the oligomer and ‘O3′ denotes the 3 oxyethylene units). The ASSPE was fabricated by a straightforward viable procedure involving uniaxial electrospinning of poly(acrylonitrile) (PAN) blended with PO3TFSI and doped with lithium bis (trifluoromethanesulfonyl)imide salt (LiTFSI). The prepared electrospun (PAN/PO3TFSI/LiTFSI) ASSPE presented an intriguing morphology following heat-treatment like the venation found on a leaf blade where the network of veins is responsible for providing support to the entire lamina. The final structure consists of a PAN framework with the ionene oligomer flowing out of and around the fibers, closing the pores of the nanofibrous mat in the process. The ASSPE having such leaf blade inspired veined morphology with closed pores exhibits a high room-temperature ionic conductivity of 1.01 × 10−3 S cm−1, an electrochemical stability window of ∼ 4.6 V, and outstanding thermal stability. The solid-state Li/LiFePO4 (LFP) batteries assembled with the (PAN/PO3TFSI/LiTFSI) ASSPE showed good Coulombic efficiency above 98% when cycled at 0.2C for 100 cycles at both 25 °C and 60 °C. Furthermore, the ASSPE showed potential application in all-solid-state lithium sulfur battery. Additionally, a flexible Li/ASSPE/LFP custom made cell was demonstrated to work even in extremely deformed conditions, such as being folded, crimped and rolled, indicating the high flexibility of the fiber based solid electrolyte.

Tunable Synchronicity of Molecular Valence Tautomerism with Macroscopic Solid-Liquid Transition by Molecular Lattice Engineering.

The combination of a cobalt-dioxolene core that exhibits valence tautomerism (VT) with pyridine-3,5-dicarboxylic acid functionalized with chains bearing two, four, or six oxyethylene units led to new complexes ConEGEspy (n = 2, 4, and 6). These complexes commonly form violet crystals of the low-spin (ls)-[CoIII (nEGEspy)2 (3,6-DTBSQ)(3,6-DTBCat)] (ls-[CoIII ], 3,6-DTBSQ = 3,6-di-tert-butyl semiquinonato, 3,6-DTBCat = 3,6-di-tert-butyl catecholato). Interestingly, violet crystals of Co2EGEspy in the ls-[CoIII ] transitioned into a green liquid, accompanied by an almost complete VT shift (94 %) to the high-spin (hs)-[CoII (nEGEspy)2 (3,6-DTBSQ)2 ] (hs-[CoII ]) upon melting. In contrast, violet crystals of Co4EGEspy and Co6EGEspy in the ls-[CoIII ] exhibited partial VT (33 %) and only a 9.3 % VT shift after melting, respectively. These data demonstrate the tunability of the synchronicity of the molecular VT and macroscopic solid-liquid transitions by optimizing the tethered chains, thus establishing a new strategy for coupling bistable molecules with the macroscopic world.

Synthesis and evaluation of magnetic surfactants for high temperature oilfield application

Magnetic surfactants are a unique class of amphiphiles that can manage self-assembly in a controlled manner in the presence of the applied magnetic field. However, any surfactant for oilfield application must be soluble in water and exhibit high heat stability as it needs to stay in harsh reservoir conditions. Herein, we report a synthesis of two new magnetic surfactants that contain different hydrophobic moieties (ethoxylated alky tail and oleic tail). The chemical structures of the magnetic surfactants and their nonmagnetic parent surfactants were elucidated by ESI-MS, NMR (1H, 13C), and FTIR analysis. Both surfactants display good aqueous solubility due to the insertion of ethoxy units and unsaturation in the hydrophobic tail. The effect of hydrophobic tails on heat and surface/interface properties was investigated. Rendering to thermal gravimetric curves, the degradation temperature of magnetic surfactants was near 270 °C. This clearly showed that the magnetic surfactants contain high thermal stability for elevated temperature reservoirs. However, the effect of change of hydrophobic tail appears to be insignificant in thermal stability tests. An analysis of the surface tension showed that magnetic surfactants were more effective than corresponding nonmagnetic surfactants exhibiting higher surface tension (γ) reduction of water even with no magnetic field. Moreover, the magnetic surfactant containing an ethoxylated alkyl tail showed more surface tension (γ) reduction of water than a magnetic surfactant with an oleic tail. The research outcome on the synthesized magnetic surfactants makes them an attractive choice in a harsh oilfield environment. To the best of our knowledge, this is the first report on the magnetic surfactants that can toleratate high temperature reservoir conditions.

Argentivorous Molecules with Oxyethylene Chains in Side-Arms: Silver Ion-Induced Selectivity Changes toward Alkali Metal Ions

Argentivorous molecules with mono, di, tri, tetra, and penta-oxyethylene chains in aromatic side-arms were prepared (L1-L5). Titration experiments using proton nuclear magnetic resonance and cold electrospray ionization (cold-spray ionization, CSI) mass spectrometry showed that silver ions were trapped in the cyclen moiety and the arranged oxyethylene chains of the side-arms when two equivalents of silver ions were added. The silver complexes formed by adding one equivalent of silver ion to L2-L5 bind alkali metal ions using the oxyethylene chains; alkali metal ion-induced CSI mass spectral changes of L2-L5 were measured in the absence and presence of silver ions to compare the binding properties of the ligand for Li+, Na+, and K+ ions. As a result, the intensity ratios of [L + H + M]2+/[L + H]+ in L1-L3 were almost zero or very low. L4 and L5, which have tetra(oxyethylene) and penta(oxyethylene) chains, respectively, bind a larger size of alkali metal ions. On the other hand, in the presence of silver ions, the ratio for [L + Ag + M]2+/[L + H]+ (M = Li, Na, K) in L2-L5 was increased. The highest [L + Ag + M]2+/[L + H]+ ratios for K+ were observed in L4 and L5, while selectivity for Na+ was observed in the case of L2 and L3. These results indicate that the increased binding ability and selectivity by L2-L5 are due to the arrangement of oxyethylene chains by the conformational change of the aromatic side-arms. The Ag+-induced carbon-13 nuclear magnetic resonance spectral changes suggested that the second and third oxyethylene units, close to the benzene, are involved in the coordination of the second metal ion.

Interfacial properties and salt tolerance of carboxylated nonylphenol ethoxylate surfactants

Ionic alkoxy-based surfactants recently attract more attentions because they possess advantages of both nonionic and anionic surfactants, and surfactant structure is the key factor affecting the interfacial property and salt tolerance of ionic alkoxy-based surfactant. In the present study, carboxylated nonylphenol ethoxylate surfactant (NPEOnC, n = 2, 4, and 7) at n-decane/water interface has been studied using molecular dynamics simulation in the absence and in the presence of NaCl with different concentrations. The interfacial activity in reducing interfacial tension and salt tolerance of NPEOnC were investigated and the effect of numbers of ethoxy unit were quantified. The interfacial activities of NPEOnC were demonstrated by the arrangement of surfactant monolayer, the structures of n-decane/water interface, and the interfacial tensions. Salt tolerance of NPEOnC were estimated by the bound pairs between surfactant and water as well as those between surfactant and Na+, especially the structural relaxation dynamics of those bound pairs. Results showed that NPEO7C exhibited the highest activity in lowering the interfacial tension of n-decane/water, and kept the interfacial activity in the presence of NaCl. Carboxyl groups were the predominant groups in binding with Na+, and ethoxy segment within NPEO4C and NPEO7C were the governing groups in being solvated with water. Moreover, the structural relaxations of bound pairs between oxygen within ethoxy segment and water/Na+ were much slower than those between oxygen within carboxyl group and water/Na+, which resulted in the higher salt tolerance of NPEOnC with more ethoxy units.

Controlling the Chain Folding for the Synthesis of Single-Chain Polymer Nanoparticles Using Thermoresponsive Polymers

Synthetic polymer single-chain nanoparticles (SCNPs) are an emerging new class of nanomaterials that possess similar folded structures as natural proteins. However, most SCNPs reported so far are p...