Synthesis and surface active properties of a gemini-type surfactant linked by a quaternary ammonium group

In this study, cationic surfactants having multi-hydroxyl groups were synthesized by the condensation reaction of octadec-9-enyl glycidyl ether and methyl amine followed by the quaternization with dimethyl sulfate. The structure of the product was elucidated by ¹H-NMR and FT-IR. The minimum critical micelle concentration (CMC) and surface tension achieved using C18:1-BHDM surfactant were 1.24?×?10^?4?mol/L and 43.36 mN/m, respectively. The interfacial tensions measured between 1 wt% surfactant solution and n-decane were found to be in the same order of magnitude as those exhibited between micellar solutions and nonpolar hydrocarbon oils. The contact angle measurement result suggests that C18:1-BADM is the best wetting agent among the surfactants tested during this study. It has been observed that the results for foam stability measurement are consistent with those of CMC and contact angle. That is, the percentage of foam volume decrease has been observed to increase with an increase in number of hydroxyl group.     

Enthalpies of Solution of Aliphatic Amines, Aliphatic Benzene, and Alkane in Dimethyl Sulfoxide at 298.15 K

The enthalpies of solution of aliphatic compounds [{aliphatic amine, H(CH₂) _n NH₂, n = 3 to 10}, aliphatic benzene {H(CH₂) _n C₆H₅, n = 0 to 8}, and alkane {H(CH₂) _n H, n = 6 to 10}] in dimethyl sulfoxide have been measured at 298.15 K in the low concentration range from x = 5 × 10^?6 to x = 0.002. The partial molar enthalpies at infinite dilution of each aliphatic compound were determined and were found to increase linearly with increasing number of methylene groups. The enthalpic group contribution of methylene, phenyl, methyl, hydroxyl, nitrile, and amine in aliphatic compounds were 1.55, 2.65, 3.81, ?2.55, ?3.71, and ?4.43 kJ-mol^?1, respectively.     

Synthesis and properties of quaternary ammonium Gemini surfactants with hydroxyl groups

The article describes synthesis of four hydroxyethyl alkylene–double alkyl bromide through substitution of nucleophilic d iethanolamine, 1-bromododecane, and 1,4-dibromobutane. The structure of the new hydroxyl cationic surfactant (HDCS) was characterized by ¹H NMR and FTIR spectra. The aqueous solution of HDCS showed critical micelle concentration, i.e., 5.6 × 10^?2 mM, and could reduce oil/water interfacial tension to 3.28 × 10^?3 mN m^?1. The surface tension measurements provided a series of parameters, including critical micelle concentration (CMC), surface tension at the CMC (γ_CMC), adsorption efficiency (pC₂₀), and effectiveness of surface tension reduction (Π_CMC). In addition, maximum surface excess concentration (Г_max) and minimum surface area/molecule (A_min) at the air/water interface were obtained by the Gibbs adsorption isotherm. The influence of inorganic salts (sodium chloride, calcium chloride) and organic salts (sodium benzoate) on the surface tension of HDCS in aqueous solution was investigated. For wettability alteration measurement, contact angle measurement as a quantitative method was utilized. Meanwhile, foam ability, foam stability, and emulsifying property of the synthesized surfactant were also examined at different concentration. HDCS also had excellent viscosity property.     

Synthesis and micellization of star‐like hyperbranched polymer with poly(ethylene oxide) and poly(ε‐caprolactone) arms

Novel star‐like hyperbranched polymers with amphiphilic arms were synthesized via three steps. Hyperbranched poly(amido amine)s containing secondary amine and hydroxyl groups were successfully synthesized via Michael addition polymerization of triacrylamide (TT) and 3‐amino‐1,2‐propanediol (APD) with feed molar ratio of 1:2. ¹H, ¹³C, and HSQC NMR techniques were used to clarify polymerization mechanism and the structures of the resultant hyperbranched polymers. Methoxyl poly(ethylene oxide) acrylate (A‐MPEO) and carboxylic acid‐terminated poly(ε‐caprolactone) (PCL) were sequentially reacted with secondary amine and hydroxyl group, and the core–shell structures with poly(1TT‐2APD) as core and two distinguishing polymer chains, PEO and PCL, as shell were constructed. The star‐like hyperbranched polymers have different sizes in dimethyl sulfonate, chloroform, and deionized water, which were characterized by DLS and ¹H NMR. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1388–1401, 2008     

Adducts of nitrogenous ligands with rhodium(II) tetracarboxylates and tetraformamidinate: NMR spectroscopy and density functional theory calculations

Complexation of tetrakis(μ₂‐N,N'‐diphenylformamidinato‐N,N')‐di‐rhodium(II) with ligands containing nitrile, isonitrile, amine, hydroxyl, sulfhydryl, isocyanate, and isothiocyanate functional groups has been studied in liquid and solid phases using ¹H, ¹³C and ¹⁵N NMR, ¹³C and ¹⁵N cross polarisation–magic angle spinning NMR, and absorption spectroscopy in the visible range. The complexation was monitored using various NMR physicochemical parameters, such as chemical shifts, longitudinal relaxation times T₁, and NOE enhancements. Rhodium(II) tetraformamidinate selectively bonded only unbranched amine (propan‐1‐amine), pentanenitrile, and (1‐isocyanoethyl)benzene. No complexation occurred in the case of ligands having hydroxyl, sulfhydryl, isocyanate, and isothiocyanate functional groups, and more expanded amine molecules such as butan‐2‐amine and 1‐azabicyclo[2.2.2]octane. Such features were opposite to those observed in rhodium(II) tetracarboxylates, forming adducts with all kind of ligands. Special attention was focused on the analysis of Δδ parameters, defined as a chemical shift difference between signal in adduct and corresponding signal in free ligand. In the case of ¹H NMR, Δδ values were either negative in adducts of rhodium(II) tetraformamidinate or positive in adducts of rhodium(II) tetracarboxylates. Experimental findings were supported by density functional theory molecular modelling and gauge independent atomic orbitals chemical shift calculations. The calculation of chemical shifts combined with scaling procedure allowed to reproduce qualitatively Δδ parameters. Copyright © 2013 John Wiley & Sons, Ltd.     

Polyoxyalkylated diethylenetriamine polymeric surfactants: molecular structure effect on thin wetting films

Thin wetting films from aqueous solution of four polyoxyalkylated diethylenetriamine (DETA) polymeric surfactants (named A, B, C, and D) are studied. Surfactants A, B, and C have a star-like structure differing only by the number of polymeric branches: four, six, and nine in the mentioned order while the forth one, D, is of a dendritic type with four to six primary and two to three secondary branches. The receding contact angles θ _r of the solution on hydrophilic SiO₂ glass surface and the contact angle θ _aq of a drop of doubly distilled water on SiO₂ glass surface pretreated with DETA polymeric surfactant solution are measured. The θ _r values on hydrophobicity of SiO₂ glass surface, respectively, increase in the following order: surfactant A, surfactant C, surfactant B, and surfactant D. The equilibrium thickness h _eq of wetting films from DETA aqueous solution on hydrophilic SiO₂ glass surface is measured using the micro-interferometric method. Results show an unexpected course of the h _eq vs. C _s curves with a maximum. Results from the studies indicate that differences in polymeric surfactant molecular structure affect the properties exhibited at air/liquid and solid/liquid interfaces, such as the value of surface tension, degree of hydrophobicity of solid surface, equilibrium film thickness, etc.     

On the thermal stability of Fe2Mn0.5Zn0.5(C2O4)4

Heat of immersion and contact angle were measured for α-Si₃N₄. The electrostatic field strength, which was determined to be 0.42×10⁵ esu cm^?2, showed that the surface is much less polar than those of oxides. Slight increase of the heat of immersion in water with the increase of outgassing temperature is attributable to the rehydration of siloxane linkages which have been formed by dehydration of silanol groups on the surface. The heat of immersion in n-alkanes increased steeply with the number of carbon, n, from n=6 to 9, and became nearly constant for n>9, while in n-alkanols the heat began to rise at n=10 after the nearly constant values for n=4 to 8. The dispersion force contribution to the total surface free energy, γ^d_s, were estimated by contact angle and heat of immersion methods which have been well applied to the low energy surfaces, and found to be 25 mJ m^?2 from contact angle and 129 mJ m^?2 from the immersional heat in hexane.     

Reversed-phase foam chromatography: Separation of trace amounts of cobalt from nickel in the tri-n-octvlamine-hydrochloric acid system

The separation of cobalt and nickel in hydrochloric acid media by reversed-phase chromatography on open-cell polyether-type polyurethane foam columns loaded with tri-n-octylamine hydrochloride has been studied. The results showed that good results are obtained with 11.4 and 17.7% loadings of the amine. The separation was studied in the Ni:Co range from 1 to 10⁸.     

Synthesis and characterization of a new silicone-based polyurethane surfactant

ω-N,N-Dihydroxyethyl aminopropylpolymethylhydrosiloxane (DAPS) a monotelechelic polydimethylsiloxane with a diol-end group, which is used to prepare polyurethane surfactant, was successfully synthesized. The preparation included four steps, which are hydroxyl protection, alkylation, hydrosilylation, and deprotection. Then, a novel silicone-based polyurethane surfactant was prepared by the addition polymerization of isophorone diisocyanate to DAPS, polypropylene glycol, and methanol and was used in the preparation of polystyrene by emulsion polymerization. The DAPS was characterized by FTIR, ¹H NMR, ¹³C NMR and elemental analysis. The results showed that each step was successfully carried out and the targeted products were synthesized in all cases.     

Synthesis and properties of cocotriethoxylpropanediamine oxide

A new kind of amine oxide surfactant – cocotriethoxylpropanediamine oxide (CTPDAO) – was synthesized by a two-step process. The molecular structure was characterized by FTIR spectra and ¹H NMR. The new surfactant showed high surface activity in aqueous solution in the surface tension measurement. Emulsifying capacity and wetting ability were studied in comparison to dodecyldimethylamine oxide (DDMAO). The results indicate that this new surfactant could reach the lowest surface tension of 30.4?mN?m^?1 in aqueous solution with a critical micelle concentration (CMC) of 0.23?mmol L^?1. The wetting ability of DDMAO is better than that of CTPDAO. Compared with CTPDAO, DDMAO shows a greater capacity to emulsify soybean oil, although CTPDAO is a better emulsifying agent for liquid paraffin. The foaming properties and thickening function of DDMAO and CTPDAO mixed with alcohol ether sulfate (AES) and dodecylbenzene sulfonate (LAS) were also investigated. The results show that CTPDAO is a superior foam stabilizer than DDMAO while CTPDAO and DDMAO both have excellent thickening functions.     

Wetting properties of aqueous solutions of hydrophobically modified inulin polymeric surfactant

The contact angles of aqueous solutions of a polymeric surfactant namely hydrophobically modified inulin (INUTEC®SP1) were measured on hydrophilic and hydrophobised quartz glass surfaces using the sessile drop technique. These measurements showed a large difference (>10°) between the advancing contact angle θ ₁ (that is measured immediately after placing the drop on the surface) and the constant contact angle θ ₂ (that is measured 30 minutes after placing the drop). In all the results only the contact angle θ ₂ was subsequently measured. θ versus INUTEC®SP1 concentration C _s curves were obtained at various NaCl concentrations both on hydrophilic and hydrophobic glass surfaces. On hydrophilic glass surface the θ versus C _s curves showed a maximum at a concentration range of 10^–6 to 2?×?10^–5 mol dm^-3 INUTEC®SP1. These curves were shifted to lower values as the NaCl concentration was increased. On such hydrophilic surface the INUTEC®SP1 molecule adsorbs with the polyfructose loops and tails oriented towards the surface leaving the alkyl chains in solution. Saturation adsorption with this orientation occurs at 2?×?10^–5 mol dm^-3 INUTEC®SP1. However, the contact angles remain quite small (<18°) indicating the presence of several hydrophilic glass patches uncovered by surfactant molecules. At C _s?>?2?×?10^–5 mol dm^-3 θ decreases with further increase of the INUTEC®SP1 concentration reaching 5° at the Critical Association Concentration (CAC) of the polymer. This indicates the formation of a bilayer of INUTEC®SP1 molecules with the alkyl chains hydrophobically attached to those of the first layer. On a hydrophobic glass surface, adsorption of INUTEC®SP1 occurs by multi-point attachment with the alkyl chains on the surface leaving the hydrophilic polyfructose loops and tails dangling in solution. This results in a gradual decrease of the contact angle with increase in INUTEC®SP1 concentration, reaching a plateau value (>85°) between 2?×?10^–5 and 2?×?10^–4 mol dm^-3. The large contact angles obtained on adsorption of the polymeric surfactant on a hydrophobic surface indicate the presence of several uncovered hydrophobic patches. These results give a reasonable picture of the adsorption and orientation of the INUTEC®SP1 molecules on both hydrophilic and hydrophobic solid surfaces.     

Sulfur-containing silsesquioxane hybrids with high refractive index and high Abbe number

Novel sulfur-containing silsesquioxane nanoparticles, (R_S–SiO_1.5) _n , having uniform size distribution, good solubility, and relatively high refractive index were synthesized by hydrolytic condensation of a triethoxysilane precursor derived from glycidol, followed by the esterification with sulfur-containing acid chlorides. Esterification of the water-soluble silsesquioxane nanoparticles with 3-(methylthio)propionyl chloride afforded silsesquioxane hybrid with a high density of chemically bonded peripheral methyl thioether groups, which was characterized by ¹H, ¹³C NMR, Fourier transform infrared spectroscopy, and thermogravimetric analysis measurements. The resulting product was soluble in various organic solvents, such as CHCl₃, acetone, tetrahydrofuran, dimethyl formamide, and dimethyl sulfoxide. The size of the sulfur-containing nanoparticles evaluated by X-ray diffraction was 2.1 nm. Transmission electron microscopy, gel permeation chromatography, and dynamic light scattering measurements indicated the formation of the nanoparticles having relatively narrow size distribution with an average particle diameter of less than 3 nm without aggregation. The sulfur content of the methyl thioether-containing silsesquioxane hybrid analyzed by elemental analysis was 16.1 %, which led to relatively high refractive index (n _D?=?1.588) and high Abbe number (34.4). Two sulfur-containing silsesquioxane hybrids with peripheral thiophene and phenyl thioether moieties were also obtained by the same procedure, and resulting hybrids showed high refractive indices of 1.605 and 1.627, and Abbe numbers of 31.8 and 24.3, respectively.     

Synthesis of polyester having pendent hydroxyl groups via regioselective dehydration polycondensations of dicarboxylic acids and diols by low temperature polycondensation

In this article, we describe the one‐step synthesis of polyesters having pendent hydroxyl groups by Lewis acid‐catalyzed, regioselective, dehydration polycondensations of diols (glycerol and sorbitol) and dicarboxylic acids [tartaric acid (TA) and malic acid (MA)] containing pendent hydroxyl groups, using low temperature polycondensation technique. Direct polycondensations of TA or MA and 1,9‐nonanediol catalyzed by scandium trifluoromethanesulfonate [Sc(OTf)₃] successfully yielded linear polyesters having hydroxyl functionality (M_n = ca. 1.0 × 10⁴). To demonstrate the reactivity of the pendent hydroxyl group, a glycosidation was performed. Poly(nonamethylene L ‐malate) showed significant higher biodegradability, compared with poly(nonamethylene L ‐tartrate) or poly(nonamethylene succinate). Stable poly(nonamethylene L ‐tartrate) emulsion could be prepared using poly(vinyl alcohol) as the surfactant, although emulsions consisting of poly(nonamethylene succinate) were unstable and phase‐separated within a few days. Furthermore, direct polycondensations of TA and diethylene glycol (DEG) or triethylene glycol (TEG) successfully produced water‐soluble polyesters having hydroxyl groups. This new polycondensation system may be extremely effective not only for advanced material design using functional monomers but also for effective utilization of biomass resources as chemical substances. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5747–5759, 2009     

The mechanism and kinetics of curing reaction of AG-80/SED system by DSC

The mechanism and kinetics of curing reaction of tetrafunctional epoxy resin (Ag-80)/novel diamines curing (SED) system were studied by non-isothermal and isothermal DSC. Different equivalent ratios of amine-epoxide give rise to different curing mechanisms. The main condensation reaction can be attributed to the reactions between the primary amine and epoxide and between the hydroxyl and epoxide when temperature is below 200°C, and to the reaction between the second-ary amine and epoxide when temperature is above 200°C. The corresponding apparent activation energies are 58.3 kJ·mol^?1 and 99.3 kJ·mol^?1 respectively. Apparent activation energies of condensation reactions between primary amine and epoxide and between hydroxyl and epoxide are just the same, which are 47.3 kJ·mol^?1.     

Effects of functional group interactions on the bimolecular and dissociation reactions of diols

The influence of functional group interactions on the bimolecular and dissociation reactions of diols were examined in a quadrupole ion trap mass spectrometer. Reactions of dimethyl ether ions with diols resulted in formation of (M + H)⁺ ions and (M + 13)⁺ ions (by net methyne addition). The product distribution depended on the relative separation of the hydroxyl groups within each diol, with the more proximate diols producing the greatest abundance of (M + 13)⁺ ions compared to (M + H)⁺ ions. The enhancement of the formation of (M + 13)⁺ ions is attributed to the capability for electrostatic interactions between the hydroxyl groups and the electropositive methylene group of the methoxymethylene reagent ion. The enhancement is most significant for diols that can adopt five- or to a lesser extent six-membered ring transition states (i.e, any 1,2 or 1,3 diol). Collision-activated dissociation (CAD) techniques, including both sequential activation experiments (MS ⁿ ) and comparison of CAD spectra for model compounds, suggest that the (M + 13)⁺ ions are protonated cyclic diethers.     

Solution conformations for the flexible 1-chloro-1,1-difluoro-2-pentanol unveiled using multinuclear magnetic resonance

The preferred conformations of a small polyfunctional molecule containing fluorine, chlorine and hydroxyl groups, the 1-chloro-1,1-difluoro-2-pentanol (CDP), were completely elucidated using ¹H, ¹³C and ¹⁹F NMR in three different solvents. While the Cl-C-C-O dihedral angle was asserted using coupling constant data for the diastereotopic fluorines, the Et-C-C-O torsional angle was analyzed by means of ¹H NMR spectra with selective irradiation of the diastereotopic hydrogens and fluorines. In addition, unusual couplings of the hydroxyl hydrogen with a diastereotopic hydrogen and fluorines provided information on the O-H orientation. The behavior of ¹J_C,F when the solvents varied agrees with a weak F???HO intramolecular hydrogen bond. These findings were corroborated, and the governing interactions rationalized with the aid of high level CCSD(T) theoretical calculations. Noteworthy, hyperconjugation involving the electron-acceptor σ*_C-Cl orbital drives the conformational equilibrium rather than the fluorine gauche effect.     

Utilizing the Alterable Solubility of Chitosan in Aqueous Solution to Synthesize Nanosized Sulfur for High Performance Li–S Batteries

We demonstrate the synthesis of cathode material with nanosized sulfur by a precipitation method making use of the alterable solubility of chitosan (CTS) in aqueous solution. Mesoporous Ketjen Black (KB) and carbon nanotube (CNT) are added as conductive agents to provide the three‐dimensional electric channels. This method can reduce the size of the sulfur particles, thus the nanosized sulfur obtained can fully contact with the conductive agent, which could increase the utilization of sulfur and improve the capacity of Li‐S batteries. Moreover, CTS with abundant hydroxyl and amine groups has strong interaction with polysulfides, which can improve the stability of Li‐S batteries. As a result, the obtained CTS/C‐S cathode containing 76 wt% sulfur delivers an impressively initial discharge specific capacity of 1141.6 mA·h·g^–1 at 0.5 C and maintains a capacity of 842.3 mA·h·g^–1 after 300 cycles. Our finding paves a way for the rational design of high‐performance sulfur cathodes for advanced Li‐S batteries.     

Synthesis of cationic N‐[3‐(dimethylamino)propyl]methacrylamide brushes on silicon wafer via surface‐initiated RAFT polymerization

Surface‐initiated reversible addition‐fragmentation chain transfer (SI‐RAFT) polymerization of N‐[3‐(dimethylamino)propyl]methacrylamide (DMAPMA) on the silicon wafer was conducted in attempt to create controllable cationic polymer films. The RAFT agent‐immobilized substrate was prepared by the silanization of hydroxyl groups on silicon wafer with 3‐aminopropylthriethoxysilane (APTS) and by the amide reaction of amine groups of APTS with ester groups of 4‐cyano‐4‐((thiobenzoyl) sulfanyl) pentanoic succinimide ester (CPSE); followed by the RAFT polymerization of DMAPMA using a “free” RAFT agent, that is, 4‐cyanopentanoic acid dithiobenzoate (CPAD) and an initiator, that is, 4,4′‐azobis‐4‐cyanopentanoic acid (CPA). The formation of homogeneous tethered poly(N‐[3‐(dimethylamino)propyl]methacrylamide) [poly(DMAPMA)] brushes, whose thickness can be tuned by reaction time varying, is evidenced by using the combination of grazing angle attenuated total reflectance‐Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, atomic force microscopy, and water contact‐angle measurements. The calculation of grafting parameters from the number‐average molecular weight, M _n (g/mol) and ellipsometric thickness, h (nm) values indicated the synthesis of densely grafted poly(DMAPMA) films and allowed us to predict a polymerization time for forming a “brush‐like” conformation for the chains. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Chemoselective synthesis of polyamides containing hydroxyl and amino substituents by direct polycondensation

A convenient method for the synthesis of polyamides containing hydroxyl and amino substituents on the aromatic rings of the backbones was developed. These polymers were prepared readily by the chemoselective polycondensation of dicarboxylic acids with diamines with hydroxyl and amino functional groups via the activating agent diphenyl(2,3‐dihydro‐2‐thioxo‐3‐bezoxazolyl)phosphonate. The model reactions were studied in detail to demonstrate the feasibility of chemoselective polycondensation. The direct polycondensation of 5‐hydroxy or 5‐aminoisophthalic acid with 4,4′‐diamino‐4″‐hydroxytriphenylmethane proceeded smoothly under mild conditions and produced the desired polyamides with inherent viscosities up to 0.73 dL · g⁻¹. The polymers obtained were characterized by IR, ¹H NMR, and ¹³C NMR spectroscopies. The polymers were readily soluble in aprotic polar solvents such as N‐methyl‐2‐pyrrolidinone, N,N‐dimethyl formamide, and dimethyl sulfoxide. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 3875–3882, 2000