Ethylene Oxide Chain Length Research Articles

High efficiency polyethylene glycol diacrylate monoliths for reversed-phase capillary liquid chromatography of small molecules

Highly cross-linked monolithic networks (i.e., polyethylene glycol diacrylate, PEGDA) synthesized from monomers containing varying ethylene oxide chain lengths were fabricated inside fused silica capillary columns for use in liquid chromatography (LC) of small molecules. Tergitol was used as a surfactant porogen in combination with other typical organic liquid porogens. Column performance was correlated with quantitative descriptors of the physical/chemical properties of the monomers and porogens using a statistical model. Solubility and viscosity values of the components were identified as important predictors of monolith morphology and efficiency. The chromatographic retention mechanism was determined to be principally reversed-phase (RP) with additional hydrogen bonding between the polar groups of the analytes and the ethylene oxide groups embedded in the monolith structure. The fabricated monolithic columns were evaluated under RPLC conditions using phenols, hydroxy benzoic acids, and alkyl parabens as test compounds. Isocratic elution of hydroxy benzoic acids at a linear velocity of 0.04cm/s using a PEGDA-700 monolith gave chromatographic peaks with little tailing (i.e., tailing factor<1.28). The chromatographic efficiency measured for a non-retained compound (uracil) using this column was 186,000plates/m when corrected for injector dead volume. High resolution gradient separations of selected pharmaceutical compounds and phenylurea herbicides were achieved in less than 18min. Optimized monoliths synthesized from all four crosslinking monomers exhibited high permeability and demonstrated little swelling or shrinking in different polarity solvents. Column preparation was highly reproducible, with relative standard deviation (RSD) values less than 2.1%, based on retention times of the phenol standards (3 different columns).

Soluble aggregates in aqueous solutions of polyion-surfactant ion complex salts and a nonionic surfactant.

Water-soluble aggregates based on two polyion-surfactant ion "complex salts", consisting of hexadecyltrimethylammonium (C16TA(+)) and polyacrylate (PA(-)) with either 25 or 6000 repeating units, with added nonionic surfactant octaethylene glycol monododecyl ether (C12E8) have been investigated. A previous phase study has shown that added C12E5 or C12E8 can solubilize complex salts in aqueous systems, and that increasing the poly(ethylene oxide) chain length of the nonionic surfactant and/or decreasing the polyion length favors dissolution. In this work we report on dynamic light scattering, NMR diffusometry, small-angle X-ray scattering, and isothermal titration calorimetry measurements performed to characterize the solubilized composite aggregates in dilute aqueous solution in terms of size and stoichiometry. It was found that mixed aggregates of polyacrylate, C16TA(+) ions, and C12E8, with almost constant stoichiometry, coexist with free micelles of C12E8 at all investigated mixing ratios. The length of the polyion only weakly affects the stoichiometry of the mixed aggregates while strongly affecting their size and water solubility.

Does the optimum hydrophilic lipophilic balance condition affect the physical properties of mixed reverse micelles? A spectroscopic investigation.

Synergism in several physical properties as realized in many mixed surfactant reverse micellar (RM) systems often manifests optimum hydrophilic-lipophilic balance (HLB), interdroplet interaction, or both. Such synergism is often desired for specific applications of RM systems; however, a proper rationale on the effect of such phenomenon imparted on the structure, dynamics, and activity of water molecules in RM waterpool is strongly demanded. In the present contribution we have investigated how the optimum HLB condition of mixed RM composed two nonionic surfactants (Igepal 210 and Igepal 630) affects the physical properties of entrapped water molecules in the RM waterpool. The studied mixed RM exhibits synergistic water solubilization behavior as a function of the mixing ratio with a maximum in solubilization capacity being reached at X(Ig630) = 0.3. Dynamic light scattering (DLS) studies show a bimodal distribution of droplet size in this region, whereas it is monomodal in terminal compositions. Fourier transform infrared spectroscopy (FTIR) study in the 3000-3800 cm(-1) region identifies a linear trend in which the content of "bound" water increases at the expense of the "network" water as the content of the hydrophilic surfactant Igepal 630 is increased in the mixture. Subnanosecond relaxation dynamics of the entrapped water as revealed by the fluoroprobe coumarin 500 corroborates a similar linear trend as observed in the FTIR measurements as the rotational diffusion gets retarded with the increase of ethylene oxide chain length of Igepal. Reaction kinetics of solvolysis of benzoyl chloride reaction, however, does not offer any linear trend as it gets slower in the optimum HLB region, the nonlinearity being a consequence of the distribution of the substrate in the different phases.

Electronic Structure and Mesoscopic Simulations of Nonylphenol Ethoxylate Surfactants. A Combined DFT and DPD Study

The aim of this work was to gain insight into the effect of ethylene oxide (EO) chains on the properties of a series of nonylphenol ethoxylate (NPE) surfactants. We performed a theoretical study of NPE surfactants by means of density functional theory (DFT) and dissipative particle dynamics (DPD). Both approximations were used separately to obtain different properties. Four NPEs were selected for this purpose (EO = 4, 7, 11 and 15 length chains). DFT methods provided some electronic properties that are related to the EO units. One of them is the solvation Gibbs energy, which exhibited a linear trend with EO chain length. DPD calculations allow us to observe the dynamic behavior in water of the NPE surfactants. We propose a coarse-grained model which properly simulates the mesophases of each surfactant. This model can be used in other NPEs applications.

Comparison of Cleaning Power Between Alcohol Ethoxylates or Methyl Ester Ethoxylates Having Different EO Chain Lengths and a Common Anionic Surfactant

Abstract Cleaning power of different surfactants was investigated using a model detergent system consisting of a PET film and stearic acid. Surfactants used were alcohol ethoxylates (AE, C12) and methyl ester ethoxylates (MEE, C12) with different ethylene oxide (EO) chain lengths. For comparison with these nonionic surfactants, anionic surfactant, sodium alkyl sulfate (AS, C12), was chosen. After depositing stearic acid, the PET film was cleaned in aqueous surfactant solutions by applying stirring as a mechanical action for soil removal. The amounts of stearic acid deposited on the PET film before and after the cleaning were obtained by binary processing of microscopic images of the PET film surface, from which the removal efficiency was calculated. The surface tension γ and the contact angle on the PET film θ of the surfactant solution were measured by the pendant drop and the sessile drop method, respectively. For the nonionic surfactants, critical micelle concentration, cmc, and γ and θ above cmc decreased with decreasing EO chain length. The removal efficiency of stearic acid increased with increasing surfactant concentration and further increase in the removal above cmc was observed in the cases of AE and MEE with EO chain length of 10. The removal efficiencies obtained in all systems had good relation with both γ and θ, indicating that the penetration of the surfactant solution between stearic acid and the PET film in the contact zone was a dominant factor in the soil removal in the present system.

Preparation of hemispherical polystyrene particles utilizing the solvent evaporation method in aqueous dispersed systems

Various nonspherical polystyrene (PS) particles were prepared by slow evaporation of toluene (used common good solvent) from homogeneous PS/hexadecane (HD)/toluene droplets dispersed in surfactant aqueous solutions at room temperature, followed by the rapid removal of HD from PS/HD particles with various phase-separated morphologies. The morphology of PS/HD particles was controlled by tuning the interfacial tension with various types of surfactants. Hemispherical PS particles with flat surfaces were obtained from phase-separated PS/HD/toluene droplets having a Janus structure, when polyoxyethylene nonylphenyl ether with an average ethylene oxide chain length of 30.8 was used as the surfactant.

Influence of polymer chain length and chains ends on polyelectrolyte solvate structure and melting point

The influence of the poly(ethylene oxide) (PEO) chain length on the thermal properties and manner of ion coordination in PEO–LiCF3SO3 electrolyte mixtures has been examined. The same form of ethoxy…Li+…CF3SO3− coordination is observed for polyethers ranging from high molecular weight (MW of 4×106) to triglyme with only four ethoxy segments. The melting points of the PEO and P(EO)3:LiCF3SO3 phases are similar with MWs of 2000 and higher, but are lowered considerably for PEO with MWs below 2000. These differences may be directly attributed to the larger fraction of methoxy chain ends present for the lower MW polymers which disrupt the ordered structures as thermal energy increases.

Promiscuous stabilisation behaviour of silicic acid by cationic macromolecules: the case of phosphonium-grafted dicationic ethylene oxide bolaamphiphiles

Phosphonium-based bolaamphiphiles have been found to stabilise silicic acid beyond its solubility limit (∼150 ppm). Three bolaamphiphiles have been tested having a quaternary phosphonium group on each end, linked by a number of ethylene oxide (EO) units (5, 21, and 91, resulting in PEGP+-200, PEGP+-1000, and PEGP+-4000 dicationic bolaamphiphiles, respectively). Specifically, the ability of PEGP+-200, PEGP+-1000, and PEGP+-4000 to retard silicic acid condensation at circumneutral pH in aqueous supersaturated solutions was explored. The goal was to investigate the effect of P-based cationic molecules, EO chain length (and by inference the P-to-P spatial separation) on silicic acid stabilisation performance. PEGP+-200 showed no stabilisation ability in “long term” tests (i.e. 24, 48, 72 h). For PEGP+-1000, and PEGP+-4000, it was discovered that in “short-term” (0–8 h) and “long term” (> 24 h) studies the inhibitory activity is additive dosage-dependent, demonstrating that there is a clear increase in stabilisation ability upon phosphonium PEG dosage increase. Specifically, soluble silicic acid levels reach 420 ppm and 400 ppm after 24 h in the presence of 150 ppm PEGP+-1000, or PEGP+-4000, respectively. PEG additives (PEG-200, PEG-1000, and PEG-4000) containing no phosphonium cations were also tested. Although PEG-200 and PEG-1000 showed no silicic acid stabilisation effects, PEG-4000, surprisingly, was a strong stabiliser. In fact, the inhibitory efficiencies of PEGP+-4000 and PEG-4000 were virtually identical. These results present strong proof that the polyethylene chain beyond a certain length strongly contributes to silicic acid stabilisation. Lastly, the effects of these boloamphiphiles on silica particle morphology were investigated by SEM. Spherical particles and their aggregates, irregularly shaped particles and porous structures, are obtained depending on the additive.

Gold clusters and nanoparticles in reverse micelles formed by tritons X-100, X-114, and X-45

The formation of gold nanoparticles and clusters in solutions of reverse micelles formed by Tritons X-45, X-114, and X-100 (polyoxyethylene isooctylphenyl ethers with degrees of polymerization n = 5, 7–8 and 9–10, respectively) in the presence of sodium sulfite is studied. The stability of these particles is shown to depend on the length of ethylene oxide chains in surfactant molecules, water content in micelles, and the presence of special additives. It is found that, on one hand, L-ascorbic acid favors a reduction of HAuCl4 and, on the other hand, affects the stability of resultant particles.

Non-ionic surfactant effects on hairless mouse skin permeability characteristics.

The influence of a range of polyethoxylated non-ionic surfactants upon the transport of methyl nicotinate across hairless mouse skin in-vitro was investigated using standard two-compartment diffusion cells. Those surfactants having a linear alkyl chain greater than C8 and an ethylene oxide chain length of less than E14 caused significant increases in the flux of methyl nicotinate. Surfactants having branched or aromatic moieties in the hydrophobic portion were ineffective. Maximum enhancement of flux was obtained using polyoxyethylene (10) lauryl ether (Brij 36T). Two possible modes of surfactant action are proposed. Initially the surfactant may penetrate into the intercellular regions of the stratum corneum, increase fluidity and eventually solubilise and extract lipid components. Secondly, penetration of the surfactant into the intracellular matrix followed by interaction and binding with the keratin filaments may result in a disruption of order within the corneocyte. The structural specificity required for the latter mechanism may explain, to some extent, the maximum activity obtained with the C12 surfactant.

Interactions and Solubilization of Disperse Dye with Modified Gemini Surfactants: Investigation Using the Taguchi Method

AbstractSince the interaction of a disperse dye with a surfactant in micelles plays an important role in textile industry, the purpose of this study was to find out the optimal conditions that describe the dye–surfactant interaction. The effects of temperature, gemini surfactant concentration and ethylene‐oxide chain length of gemini surfactants were investigated and optimized using the Taguchi method. First, this method was adopted to carry out the parameter design, and the interaction parameters that would affect the absorbance of UV–visible spectrum were chosen as the control factors. After the selection of an appropriate orthogonal array, an analysis of variance was applied to decide upon the optimal conditions of solubilization parameters and determine the significant factors of the UV–visible absorbance. The optimized conditions were as follow: surfactant concentration 5.6 × 10−4 M, length of ethylene oxide chain 20, and temperature 40 °C. Finally, the experimental results of confirmation tests with a confidence interval of 95%, indicated that the experiment is reliable and reproducible. Under these optimum conditions, it was also determined that the solubilization of disperse dye using modified gemini surfactants increased when the surfactant concentration and the ethylene oxide chain length increased.

One-pot preparation of three-component oil-in-water high internal phase emulsions stabilized by palm-based laureth surfactants and their moisturizing properties

In the present study, olive and olein oils had been used for the preparation of three-component high internal phase emulsions with oil volume fraction of more than 0.77 stabilized by palm-based laureth surfactants for the first time, respectively. These emulsions were easily prepared by one-pot homogenization. The critical micelle concentration and Gibbs energy of the as-synthesized surfactants were determined and discussed. Likewise, the morphology, structural properties, stability and hydration efficacy of the as-prepared emulsions were investigated. Droplet size distribution observed from the optical micrographs was in agreement with the light scattering results which suggested that droplet size increased with increasing ethylene oxide chain length. The rheological measurements of the emulsions at room (25°C) and elevated (40°C) temperatures were interpreted to give clear and direct explanation on the structure and stability of the emulsions. The hydration efficacy of the emulsions was examined in vivo using a corneometer. Both the emulsions containing olive and olein oils, respectively exhibited high stability as indicated by the rheological measurements and the structural properties did not differ from one another. However, olein oil’s hydration efficacy was higher than olive oil’s, suggesting that olein oil could well be a potential moisturizing lipid which might interest the dermatologists.

Palm‐Based Nonionic Surfactants as Emulsifiers for High Internal Phase Emulsions

AbstractIn the present study, a series of as‐synthesized palm‐based nonionic surfactants with various hydrophile–lipophile balance values were successfully synthesized. The critical micelle concentration and the Gibbs energy of the surfactants were determined and discussed. For the first time, the surfactants were used to stabilize three‐component olein oil‐in‐water high internal phase emulsions, with an oil volume fraction of 0.85, and which were easily prepared by one‐pot homogenization. Proof of high stability was confirmed by the satisfactory rheological profiles and further enhanced by a three‐month storage exercise at an elevated temperature which showed no significant physical and rheological changes. These results suggest that low concentration of the surfactants efficiently stabilized the emulsions with high content of oil. Based on the optical micrograph observation, an average droplet size of less than 10 μm increased with increasing ethylene oxide chain length and temperature. The varying degree of viscosity resulted from the various ethylene oxide chain lengths of the surfactants. The hydration efficacy of the emulsions was examined in vivo using a corneometer. The impressive hydration efficacy of olein oil suggests that it could well be a potential moisturizing lipid which might interest dermatologists.

Photophysics and Rotational Dynamics of a β-Carboline Analogue in Nonionic Micelles: Effect of Variation of Length of the Headgroup and the Tail of the Surfactant

Effect of variation of length of nonionic surfactants in terms of the headgroup as well as the tail part on the photophysical and rotational dynamical properties of a beta-carboline analogue, 3-acetyl-4-oxo-6,7-dihydro-12H-indolo-[2,3-a]quinolizine (AODIQ) has been investigated. Steady-state and time-resolved fluorescence and fluorescence anisotropy have been exploited for the purpose. The experiments revealed modification of the photophysics of AODIQ by the conjugate effect of polarity and rigidity of the micellar environments with varying poly(ethylene oxide) chain length in the case of Triton X series and the alkyl chain length in the case of Tween series surfactants. Fluorometric studies suggest that the fluorophore resides at the micelle-water interface in all these systems. The enhancements in the steady-state anisotropy in all the micellar media compared to those in pure aqueous solution reflect that the fluorophore is located in motionally restricted regions introduced by the nonionic micelles. Contrary to the single exponential nature of the fluorescence anisotropy decay of AODIQ in aqueous medium, they were found to be biexponential in the micellar environments. The rotational relaxation of AODIQ in the micellar environments has been discussed in light of the two-step and wobbling in a cone model. The model helps to evaluate different rotational parameters and to ascertain the location of the fluorophore in the micellar media. The significant feature is that the motional restriction decreases with an increase in the poly(ethylene oxide) chain length while it increases with an increase in the alkyl chain length. The difference in the extent of water penetration due to variation in the thickness of the palisade layer and therefore a variation in the micellar polarity with a variation of the length of poly(ethylene oxide) and alkyl chain has been argued to be responsible.

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.

Surfactant-Mediated Modulation of Hydrophobic Interactions in Associative Polymer Solutions Containing Cyclodextrin

The ability of nonionic surfactants to modulate the rheological characteristics of comblike hydrophobically modified associative polymer solutions containing cyclodextrin (CD) is examined. Addition of either alpha- or beta-CD to these polymers results in a marked decrease in solution viscosity and viscoelastic properties because of the encapsulation of the polymer hydrophobes by CD. Nonionic surfactants, introduced to such a system, alter the hydrophobic interactions by competing with the polymer hydrophobes for complexation with the CDs. In this regard, nonylphenol ethoxylates (NPe) with different ethylene oxide chain lengths, which determine the hydrophilic-lipophilic balance (HLB) of the surfactant, are used. Our results reveal that the extent and rate of recovery of zero shear viscosity as well as dynamic moduli are strongly influenced by the type of CD (alpha versus beta) as well as the HLB of the surfactant. For polymer solutions containing alpha-CD, recovery is observed solely in the presence of a low-HLB surfactant (NP6 and NP8). Additionally, in the case of NP6, the viscosity increases monotonically above the original hydrophobically modified alkali-soluble emulsion viscosity with surfactant addition, whereas for that of a higher HLB surfactant (NP15), the viscosity shows no appreciable change. In the case of beta-CD, on the other hand, a complete recovery as well as further enhancement of rheological properties is achieved using the above surfactants. However, the trends of viscosity modulation are dissimilar for different surfactants as we witness a monotonous increase in the case of NP6 while a maximum in viscosity is observed in the presence of NP8 and NP15. The contrasting observations can be explained in terms of varying affinities of alpha- and beta-CDs to bind with NP surfactants and the existence of different micellar structures in solution as governed by surfactant HLB. These results are further confirmed by UV/vis spectroscopy and cloud point measurements.

Interplay between the Surface Adsorption and Solution-Phase Behavior in Dialkyl Chain Cationic−Nonionic Surfactant Mixtures

Neutron reflectivity, NR, and surface tension have been used to study the adsorption at the air-solution interface of mixtures of the dialkyl chain cationic surfactant dihexadecyl dimethyl ammonium bromide (DHDAB) and the nonionic surfactants monododecyl triethylene glycol (C12E3), monododecyl hexaethylene glycol (C12E6), and monododecyl dodecaethylene glycol (C12E12). The adsorption behavior of the surfactant mixtures with solution composition shows a marked departure from ideal mixing that is not consistent with current theories of nonideal mixing. For all three binary surfactant mixtures there is a critical composition below which the surface is totally dominated by the cationic surfactant. The onset of nonionic surfactant adsorption (expressed as a mole fraction of the nonionic surfactant) increases in composition as the ethylene oxide chain length of the nonionic cosurfactant increases from E3 to E12. Furthermore, the variation in the adsorption is strongly correlated with the variation in the phase behavior of the solution that is in equilibrium with the surface. The adsorbed amounts of DHDAB and the nonionic cosurfactants have been used to estimate the monomer concentration that is in equilibrium with the surface and are shown to be in reasonable qualitative agreement with the variation in the mixed critical aggregation concentration (cac).

Incorporation of nonionic emulsifiers inside styrene–methacrylic acid copolymer particles during emulsion copolymerization

Emulsion copolymerizations of styrene and methacrylic acid with polyoxyethylene nonylphenyl ether nonionic emulsifiers having various hydrophilic–lipophilic balance (HLB) values (13.7, Emulgen 911; 15.5, Emulgen 920; 17.2, Emulgen 931) were performed. The incorporation behavior of the nonionic emulsifiers, comprising polydisperse poly(ethylene oxide) (PEO) chain lengths, inside the particles was investigated. At the completion of the polymerization, the incorporated percentage of the lowest HLB emulsifier was 61%, much higher than that of the highest HLB one (10%). In both polymerizations, the amounts of the incorporated emulsifiers increased with conversion, and shorter PEO chain (i.e., lower molecular weight) components were predominantly incorporated over longer PEO chain components.

The effect of calcium ion on the biodegradation of octylphenol polyethoxylates, and the antiandrogenic activity of their biodegradates

Because limes have been used as important fertilizers to neutralize acidified farmland in Japan, our interest in this study was focused on the effect of calcium ion on the biodegradation of octylphenol polyethoxylates (OPEOn) by a pure culture of Pseudomonas putida S5 isolated from a rice paddy field in Japan. In the presence of calcium ion, P. putida S5 accelerated the formation of octylphenol oligoethoxy carboxylates (OPECn) rather than that of octylphenol oligoethoxylates under an aerobic condition, indicating that more soluble biodegradates with terminal carboxyl group may liquate out easily to surface and ground water rather than more hydrophobic biodegradates with shorter ethylene oxide residues. Therefore, the androgen receptor (AR) activity of their degradation products was characterized using an in vitro reporter gene assay. As ethylene oxide chain length decreased, the biodegradates, OPEOn (n < 3), increased their AR antagonist activity. However, OPECn (n < 3) were unable to determine their AR activity because of their cytotoxicity in our reporter gene assay system.

Synthesis of oligomeric urethane dimethacrylates with carboxylic groups and their testing in dental composites

AbstractCarboxyl urethane dimethacrylate oligomers with poly(ethylene oxide) sequences in the structure were synthesized and examined in photopolymerizable resins that could better adhere to various kinds of materials, including tooth substrates. Aspects of the morphogenesis of dental composites formed through a photochemically initiated radical copolymerization of the carboxylic derivatives, in addition to other partners encountered frequently in such materials, were studied comparatively with the corresponding urethane dimethacrylate monomer. The effect of a small quantity of a carboxylic macromer (ca. 10%) on the formation of a network with a non‐carboxyl urethane dimethacrylate oligomer (90%) as a potential substitute for diglycidyl methacrylate of bisphenol A and a filler (1/1 70% Aerosil/glass) was visualized by fluorescence spectroscopy with a pyrene methanol probe. The results showed the following: (1) the degree of conversion in the formulations into which carboxyl urethane dimethacrylate was incorporated decreased with increasing poly(ethylene oxide) chain length, (2) the formation of excimers was inhibited in the derived composites, and (3) an important quenching of the monomer fluorescence emission with the UV–vis irradiation time was observed in the formulation containing a filler (Aerosil+Zr/Sr glass). Preliminary testing of the resin composites suggested that all urethane oligomers containing carboxylic acid could lead to dental materials with reduced polymerization shrinkage and good mechanical properties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1956–1967, 2007