Ethylene oxide oligomer distribution in nonionic surfactants via high performance liquid chromatography (HPLC)

A high performance liquid chromatography (HPLC) method using adsorption columns combined with linear gradient elution has been developed for the determination of ethylene oxide (EO) distribution in nonionic surfactants. The quantitative ethoxylate adduct distribution in single-carbon-number and mixed-carbon-number primary alcohol-based samples can be obtained. The HPLC method is also applicable for determining the molar EO distributions in diverse ethylene oxide adduct compounds such as alkylphenol ethoxylates, branched alcohol ethoxylates and secondary alcohol ethoxylates. Nonionic surfactant samples containing adducts up to 25 mol have been successfully separated and the individual adducts quantitated.     

Gas chromatographic analysis of nonionic surfactants by acid cleavage of ether linkages

The gas chromatographic analysis of various kinds of nonionic surfactants has been carried out after chemical decomposition using the mixed anhydride of acetic and p-toluene sulfonic acids which acts as a reagent for cleavage of ether linkages. The gas chromatographic peaks of the reaction products show the alkyl distributions of the hydrophobic groups of ethylene oxide adducts. The alkyl compositions closely agree with those of the starting materials. In this way, the hydrophobic groups of polyoxyethylene alkyl ether, polyoxyethylene alkyl phenol ether, polyoxyethylene alkyl amine, and polyoxyethylene alkyl thioether have been analyzed. At the same time, the hydrophilic group, namely polyoxyethylene group, can be identified in the form of ethylene glycol diacetate.     

Preparation of detergents from formaldehyde

A process was developed for condensing different mol ratios of dodecanol, formaldehyde and ethylene oxide to form a series of adducts with useful detergent properties. These products are analogous to the commercially important class of nonionic surfactants produced by treating fatty alcohols with ethylene oxide to produce a homologous series of adducts. The structures were shown to be represented by RO[(CH₂O)_x(CH₂CH₂O)_y]R where R is either dodecyl or hydrogen, x and y are integers (including zero), and it is understood that the oxymethylene and oxyethylene groups are intermingled in the ether chains. Unfortunately, we were unable to produce commercially viable detergent compositions. For these, our calculations indicate that a dodecanol:HCHO:EO mol ratio between 1:3:4 and 1:5:2 would be necessary both for good detergency and good economics. With acidic catalysts such as BF₃, the condensation is facile and product with desired overall mol ratios can be produced. However, much of the formaldehyde and ethylene oxide are incorporated into by-products that either detract from the detergency properties (e.g., terminal ethers where both R groups are dodecyl) or make the mixtures unacceptable as detergents (e.g., 1,4-dioxane). Because of the presence of terminal ethers, the detergent properties are similar to those of propylene oxide adducts rather than ethylene oxide adducts. With selected basic catalysts most of the harmful by-products can be eliminated, but the reaction rates and conversions are unsatisfactory. Basic catalysts that give high reaction rates convert most of the formaldehyde fed to methyl formate.     

ADSORPTION OF ETHOXYLATED NONIONIC SURFACTANTS FROM SILOXANE-BASED SOLVENT AND AQUEOUS SYSTEMS: USE OF QCM AND MODEL POLYMERIC SURFACES

Adsorption behavior was quantified with pure ethoxylated nonionic surfactants onto different polymeric surfaces (hydrophilic cotton and hydrophobic polyester) and model hydrophilic gold surface. The polymer materials used for the study were characterized using SEM. The role of ethylene oxide group variation in surfactant-polymer interaction was established using pure surfactant with the same alkyl chain length but varying ethoxylate chain lengths. It was observed that surfactant with more ethylene oxide groups per molecule, being more hydrophilic, interacts favorably with cotton in the hydrophobic siloxane solvent environment. The adsorption of the pure surfactants on model gold surface from hydrophobic solvent and water was also established using the quartz crystal microbalance with dissipation monitoring (QCM-D) system. Effect of ethylene oxide chain length and surfactant concentration on the extent of adsorption was quantified. At the gold-water interface, the plateau adsorption for C₁₂ E₃ (15.9 × 10^?6 mole/m²) is about four times higher than for C₁₂E₈. An opposite trend was observed for adsorption of the surfactants on gold in the hydrophobic D5 environment. Information about thickness, adsorption and desorption kinetics, and structure of adsorbed layer was obtained from the QCM-D frequency-dissipation data. The study is an important contribution towards fundamental understanding of applications involving the use of ethoxylated nonionic surfactants.     

Self-Assembly of Polyethylene Glycol Ether Surfactants in Aqueous Solutions: The Effect of Linker between Alkyl and Ethoxylate

The aqueous self-assembly behavior of two homologous series of poly(ethylene oxide) (PEO)-containing nonionic surfactants based on a C₁₀-Guerbet hydrophobe is reported. The two families of surfactants, alkyl ethoxylates and alkyl alkoxylates, are commercially available from BASF under the trade name Lutensol® XP-series and XL-series, respectively. The latter incorporate propylene oxide (PO) units in the surfactant chain. Dye solubilization was used to determine the critical micellization concentration (CMC) of each surfactant at 22 and 50 °C. The PO-containing alkyl alkoxylates displayed lower CMC values, which were also more sensitive to temperature. The Gibbs free energy, enthalpy, and entropy of micellization were computed from the CMC data and used to identify the contribution of each surfactant moiety (alkyl chain, PO unit, and PEO block) in controlling the CMC. The micellization properties are compared with compositionally similar surfactants with linear alkyl chains, yielding information about the effects of the Guerbet alkyl chain on micellization. Isothermal titration calorimetry was also used to characterize the CMC and enthalpy of micellization which generally compare well with the dye solubilization results. Cloud point data reveal nonmonotonic relationships for the Lutensol® surfactants with respect to composition, unlike linear alkyl chain surfactants. Finally, dilute solution viscosity measurements performed on some Lutensol® surfactants show a change in the slope, suggesting a structural change that tends to be more pronounced for surfactants with longer PEO blocks. The data presented herein enhance the understanding of surfactant structure–property relationships required for industrial formulation.     

Compatibility of nonionic surfactants with membrane materials and their cleaning performance

Membranes applied in industrial processes, such as for the desalination of seawater as well as for dairy and beverage industry are subjected to fouling resulting in a decline of their performance. In order to regain the flux of the membranes, cleaning procedures are conducted, whereby inorganic scale is often removed with acids and organic matter with surfactants under alkaline conditions. Currently, either ionic surfactants or alkylphenol ethoxylates are utilised to clean membranes of organic matter. Other nonionic surfactants (i.e. fatty alcohol ethoxylates) are not applied, due to the assumption that they irreversibly adhere to the membrane surface and thereby clog the pores. At BASF we have studied the adsorption of a wide range of nonionic surfactants to membrane materials. It was shown, that the affinity of nonionic surfactants critically depends on their structure. Linear alkyl ethoxylates irreversibly adsorb to the membrane surfaces, whereas branched alkyl ethoxylates do not. In a second step, we tested the cleaning performance of nonionic surfactants. Similar to the results for adsorption, a structure-performance relationship was discovered where several branched alkyl ethoxylates showed excellent cleaning results. In a third step, combinations of nonionic surfactants, chelating agents and enzymes were tested in terms of cleaning efficiency. All tested combinations showed excellent cleaning performance on bacterial fouling layers.     

A determination of the apparent molar absorption coefficients of the cobalt thiocyanate complexes of nonylphenol ethylene oxide adducts

Cobalt thiocyanate is used as a colorimetric reagent to determine traces of polyoxyethylene nonionic surfactants. It has been established that when there is an insufficient number of oxide units per hydrophobe the color intensity is markedly diminished, and with smaller numbers of oxide units the color fails to form altogether. the exact number of oxide units at which the colorimetric procedure fails has not been established previously, due to the unavailability of the pure individual ethylene oxide adducts. The individual ethylene oxide adducts of high purity were obtained by liquid chromatography on silica gel. The mixed solvent used was originally developed for thin-layer chromatography and was applied without change to column chromatography. The composition of the separated isomers has been determined by infrared, ultraviolet, nuclear magnetic resonance, and mass spectroscopy. The apparent molar absorption coefficients have been obtained for the individual cobalt thiocyanate complexes both in benzene and chlorform. For the low molecular weight adducts studied, the efficiency of color development and extraction into the organic phase has been found to be dependent on the concentration of the cobalt thiocyanate reagent. A saturated aqueous solution of cobalt thiocyanate was found to be preferable and benzene was found to be a more reliable extractant than chloroform. The apparent molar absorption coefficients do not vary linearly with chain length at low molecular weights and the minimum number of ethylene oxide units that will form an extractable color with the saturated reagent was found to be 3.     

Wettability of Aqueous Solutions of Eco-Friendly Surfactants (Ethoxylated Alcohols and Polyoxyethylene Glycerin Esters)

Wettability of aqueous solutions of ethoxylated alcohols (EA), polyoxyethylene glycerin esters (PGE) and mixtures of them have been studied. For the EA assayed, the best wettability is reached when the EA have the lowest alkyl chain length and the lowest number of ethylene oxide units in the molecule. The best wettability for the PGE assayed is reached when the number of ethylene oxide units in the molecule is lowest. Aqueous solutions of these mixtures show a wetting power between those of the pure surfactants. The wettability of PGE can be improved by adding EA with a low alkyl chain length and a low number of ethylene oxide units. An exception and synergistic effect has been detected for aqueous solutions of EA (with alkyl chain length 12–14, number of ethylene oxide units 11) and PGE (with a number of ethylene oxide units equal to 2). These mixtures have better wettability than the surfactants separately, so that it might be advantageous to use both surfactants together.     

Biodegradation of sodium alkyl poly(oxyalkylene)sulfates

The biodegradability of sodium alkylpoly(oxyalkylene)sulfates was studied under aerobic conditions by oxygen consumption, total organic corbon (TOC) and methylene blue active substance (MBAS) measurements. MBAS of linear alkylpoly(oxyalkylene)sulfates with propylene oxide (APS) or ethylene oxide (AES) disappeared within 5 days, whereas AES with branched alkyl chains were degraded less than linear AES. APS with propylene oxide from 1 to 3 mol showed BOD/ThOD values of more than 40% after 6 days. Therefore, these surfactants are considered to be readily biodegradable. In comparison to the biodegradability of APS and AES, the existence of propylene oxide groups resulted in a slight decreasing in oxygen consumption and TOC removal. Linear APS with PO of 1~3 mol were degraded according to Swisher's distance principle up to a C₁₆ alkyl chain length. That is, increasing distance principle up to a C₁₆ alkyl chain length. That is, increasing distance between sulfate and chain end increased the rate of biodegradation of these surfactants. Furthermore, from the biodegradation test of³⁵S-C₁₂E₃S, it is suggested that the initial step of biodegradation is attack on the terminal methyl group.     

Mixed Micelles of Surface Active Ionic Liquid (SAIL)–Octylphenol Ethoxylate: A Novel Reaction Medium for Selective Oxidation of Toluene to Benzaldehyde

Ionic liquids have been found to be suitable alternatives to volatile organic solvents in chemical transformation. Through a proper choice of cations and anions, the properties of an ionic liquid can be tuned so that it resembles an amphiphile. Such specially designed molecules are known as surface-active ionic liquids (SAIL). Like conventional surfactants, SAIL also form aggregates in an aqueous medium. Studies show that the mixing of SAIL with conventional surfactants leads to synergistic micellization. However, very few reports are available on the application of such systems as reaction media. Present study focuses on the application of mixed micelles of 1-tetradecyl-3-methylimidazol-1-ium bromide, ([C₁₄mim]Br) with nonionic surfactant, Octylphenol ethoxylate with 10 moles of ethylene oxide (OPE-10). Enhanced solubilization and selective catalytic oxidation of toluene using hydrogen peroxide as an oxidant and tungstic acid as a catalyst have been studied in detail using this system.     

Forecasting the cloud point of alkoxylated nonionic surfactants

The highest effectiveness of detergency for nonionic surfactants is observed in the proximity of the cloud point. This phenomenon is primarily influenced by surfactant molecular structure, such as carbon chain length and type of the hydrophilic components. Target of this investigation is to identify a relationship between the cloud point and the structure of nonionic surfactants based on ethoxylated (C_nE_m), ethoxylated-propoxylated (C_nE_mP_p) and propoxylated-ethoxylated (C_nP_pE_m) fatty alcohols. Three hundred and fifty nonionic surfactants have been prepared for this purpose. These surfactants differ in the C-chain lengths, C₄/C₆ to C₂₀/C₂₂, and the amount of ethylene oxide (EO range [n] 2–22 ethoxylation) and propylene oxide (PO range [p] 0–12 propoxylation) moieties. Mapping the differences in the performance allows us to propose a high-accuracy topological model describing the structure influence on the cloud point.     

The effect of plasticization and pH on film formation of acrylic latexes

The effect of several variables relevant to film formation in 49 : 49 : 2 poly(methyl methacrylate-co-butyl acrylate-co-methacrylic acid) latexes were studied. Plasticization of the terpolymer by both an anionic [sodium dodecyl benzene sulphonate (NaDBS)] and a nonionic [nonyl phenol ethylene oxide adduct (NP40), forty ethylene oxide units on average] surfactant were investigated. Dynamic mechanical measurements indicated that NP40 plasticized the polymer, whereas NaDBS did not. This was attributed to the compatibility of the nonionic emulsifier and the polymer. The influence of the surfactants on the film formation process was studied using minimum film temperature (MFT) measurements and scanning electron microscopy (SEM). As expected, the MFT was independent of NaDBS concentration. However, the MFT was also independent of NP40 concentration. Film formation was further investigated using SEM. The series of micrographs at varying NaDBS concentrations showed no effect on the degree of film fusion. However, surface exudates were observed. The micrographs revealed that increasing NP40 content resulted in an apparently greater degree of film coalescence. That is, there was bridging of the particles in the interstitial regions. This was attributed to localized plasticization of the polymer in these regions by NP40. The effect of water plasticization of the latex polymer was studied using dynamic mechanical measurements. The physical character of the terpolymer was varied using mol wt modifiers (CBr₄ chain transfer agent and ethylene glycol dimethacrylate crosslinker). It was found that all of the polymers were plasticized by water. Finally, the film forming behavior was investigated as a function of latex pH. MFT measurements indicated an independence of pH. © 1993 John Wiley & Sons, Inc.     

Synthesis,Quantum Chemical Calculations and Properties of Nonionic and Nonionic–Anionic Surfactants Based on Fatty Alkyl Succinate

Two surfactants based on maleic anhydride were synthesized by esterification with fatty alcohols C₁₀, C₁₂ and C₁₄ to produce half esters [I–III]. Nonionic surfactant monoesters [I–III]a–c synthesized by ethoxylation of [I–III] with different moles of ethylene oxide [6, 8 and 10] in the presence of K10 clay as an untraditionally catalyst. The later products were sulfonated to produce nonionic–anionic surfactants [IV–VI]a–c. The structures of synthesized surfactant were elucidated by FTIR and ¹H-NMR data. Their surface activity and biodegradability were determined. All the synthesized surfactants showed good surface activity and biodegradability, but anionic-nonionic type has better effect than nonionic one. Quantum chemical calculations were utilized to explore the electronic structure and stability of these compounds. Computational studies have been carried out at the PM3 semiempirical molecular orbitals level, to establish the highest occupied molecular orbital–lowest unoccupied molecular orbital, ionization potential energy and ESP mapping of these compounds. Also, the absorption, distribution, metabolism, elimination and toxic properties were studied to gain a clear view of the oral bioavailability of these compounds.     

Nonionic surfactant polarity index determination by inverse gas chromatography

Polyglycol nonionic surfactants are widely used in industrial and consumer products. Two classes of these surfactants, made from selected combinations of 1,2-butylene oxide, propylene oxide and ethylene oxide, were compared to alcohol ethoxylate (AE) and nonyl phenol ethoxylate nonionic surfactants in this study. Polyglycol copolymers consisted of either a polypropylene glycol (PPG) or polybutylene glycol (PBG) central hydrophobe. Ethoxylation of the hydrophobes produced polyethylene glycol hydrophilic blocks. Differences in hydrophobe polarity were determined by inverse gas chromatography (IGC). IGC is a useful analytical method by which the physical and chemical characteristics of a material are studied. The stationary surfactant material under study was coated onto an inert support and used as the packing for the column. A probe mixture, containing simple organic molecules of varying polarity, was injected, and the retention characteristics were measured. The retention characteristics of the standard probe mixture were used to reveal relative polarity information about the stationary surfactant coatings. Polarities of the four hydrophobes were (in decreasing order): PPG, PBG, nonyl phenyl and fatty alkyl. Comparisons were then made between the calculated hydrophile-lipophile balance values and polarity indices of the hydrophobes and their ethoxylates. The effects of hydroxyl groups on polarity were also studied and quantified.     

HPLC analysis of nonionic surfactants. Part IV. Polyoxyethylene fatty alcohols

A high performance liquid chromatographic technique (HPLC) was applied to analyze nonionic surfactants of ethylene oxide (EO) adducts. Pattern analyses of EO adducts (ethers), with 2, 10 and 20 average EO units, were carried out using a Lichrosorb SI-60 (10 μm) column (4.6 mm inner dimension (id)×25 cm) under the following conditions: mobile phase-mixture of isopropanol, methanol and n-hexane (gradient): temperature of 50 C: UV detector at 220 nm. No derivatization of the compounds was needed. An improved baseline, in spite of gradient elution, was achieved by adding negligible amounts of anthracene to the eluents. Brominated ethoxylated alcohols, resulting from the addition of bromine to the hydrophobic chain of the ethoxylated fatty alcohol, did not require any changes in the elution conditions.     

Emulsion polymerization of styrene using mixtures of hydrophobically modified inulin (polyfructose) polymeric surfactant and nonionic surfactants

Polystyrene latex dispersions were prepared by emulsion polymerization, using a mixture of hydrophobically modified Inulin (INUTEC® SP1) and various nonionic surfactants (cosurfactants). Two series of nonionic surfactants were used, namely Synperonic A (C_13–15 alkyl chain with 7, 11, and 20 moles of ethylene oxide, EO) and Synperonic NP (nonylphenol with 10 and 15 moles of EO). For 5 wt % latex, the INUTEC SP1 concentration was kept constant at 0.0165 wt % and the initiator concentration was also kept constant at 0.0125 wt %, whereas the cosurfactant concentration was varied between 0.1 and 0.5 wt %. With the exception of Synperonic A20, all other cosurfactants showed an initial increase in particle diameter followed by a decreased reaching a value comparable with that obtained using INUTEC SP1 alone. However, A20 produced a continuous reduction in particle diameter with increase of surfactant concentration, reaching a value of 100 nm at 0.5 wt % which is lower than the value obtained using INUTEC SP1 alone (188 nm). In all cases, addition of a cosurfactant enhanced the stability of latexes by co‐adsorption at the solid–liquid interface. The enhanced stability produced by the addition of cosurfactants to INUTEC SP1 could be illustrated by using the mixture of INUTEC SP1 and Synperonic A7 at 40 wt % of styrene latex concentration. In this case, the mixture produced lower particle size, much lower polydispersity index and much higher stability. These results are of significant value for industrial applications. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

A review of ethylene oxide condensation with relation to surface-active agents

Summary A limited presentation has been made in the preceding discussion of some of the more important aspects of ethylene oxide condensation with respect to surface-active agents. As a commercial process it is an economical means of introducing hydrophilic ethoxy groups to achieve the desired balance with lipophiles. The hydrophilic characteristics of ethoxy groups result from hydration of ether-linked oxygen atoms. The condesation of ethylene oxide with compounds having active hydrogen atoms is carried out commercially at moderate temperatures and pressures in the presence of catalysts with careful regard to safe operating procedures. Nonionic agents having a variety of properties and uses are formed by condensing ethylene oxide with alkyl phenols, higher aliphatic alcohols, polyhydric alcohol partial esters, carboxylic acids, higher alkyl amides, alkyl mercaptans, and polypropylene glycols. Condensation of ethylene oxide with higher alkyl amines yields cationic agents. In recent years a considerable volume of literature has been published on the subject of ethylene oxide and nonionic surface-active agents. The references cited should serve as a source of more complete and detailed information.     

Nonionic Isatin Surfactants: Synthesis,Quantum Chemical Calculations,ADMET and Their Antimicrobial Activities

The most challenge task in the building up of surface-active molecules is maximizing their surface activity with good biological activity. A nonionic surfactant (N-isatin-EO _m-C _n where m is 5, 7 and 9 ethylene glycol units and n is 8, 10 and 12) is achieved by first reacting isatin with chloroacetic acid and then with different types of ethoxylated (C₈–C₁₂) fatty alcohols that possess 5, 7 and 9 ethylene oxide units. The prepared surfactants were characterized by FTIR and ¹H NMR to confirm the structure. The surface activity, biodegradability, antimicrobial, and antifungal activity of the surfactants were evaluated. In addition, quantum chemical calculations and computations of oral bioavailability were performed. The obtained data show that all the synthesized compounds had good surface activity, biodegradability and biological activity.     

Selecting the optimal linear alcohol ethoxylate for enhanced oily soil removal

Use of nonionic surfactants in detergent products has become increasingly popular because of their tolerance to hardness ions and their effect on lowering the critical micelle concentration of anionics. Their performance as detergents, however, is very sensitive to changes in temperature and electrolyte concentration, which need to be carefully controlled in order to ensure that phase inversion conditions prevail. For a fixed temperature in an application, the only variables available for optimizing the performance of a system containing nonionics are: the type of nonionic, and the concentrations of electrolytes and anionics. Based on the mutual interactions of these ingredients in mixed systems, we have devised some guidelines for selection of the optimal ethylene oxide (FO) chain length in lauryl alcohol ethoxylate type of nonionics for a range of electrolytes and anionic surfactant concentrations. For any given concentration of electrolytes (sodium carbonate and sodium tripolyphosphate), anionic (sodium linear alkyl benzene sulfonate) and nonionic, the detergency of synthetic sebum from blended polyester/cotton fabrics shows a maximum as a function of average FO moles in the nonionic. Oil/water interfacial tension shows an expected reverse trend. The optimal EO moles (for maximal detergency) show a monotonically increasing trend when plotted as a function of the ratio of nonionic to anionic concentration for a fixed level of electrolyte. The optimal EO moles also increase with increasing level of electrolytes in the system. However, the effect of nonionic/anionic ratio is much stronger than the effect of electrolytes on the optimal EO moles.     

Zum Wesen des Trübungspunktes nichtionogener Tenside

Turbidity Point of Nonionic Surfactants The occurrence of turbidity above a definite temperature in aqueous solutions of many nonionic surfactants, especially in those of ethylene oxide adducts, is due to separation of two liquid phases and not due to dehydration of the hydrophilic group, as is often assumed. In discussing the above phenomenon, the thermodynamic laws governing the resolution of liquid two-component systems are taken into consideration.