Poly Ethylene Oxide Surfactant Research Articles

CH4 and CO2 adsorption–desorption-diffusion characteristics in surfactant-modified coal under microscopic conditions

Hydraulic techniques are integral to both coal mining and gas extraction procedures, and the precise inclusion of surfactants in hydraulic fracturing fluids serves as a crucial factor influencing the wettability of coal and facilitating gas desorption. Nevertheless, relatively few investigations have focused on the influence of surfactants within coal on the adsorption–desorption-diffusion dynamics of gases. In this study, Xin Tian high-rank coal was treated with different surfactants, and the pore structure and functional groups of the coal samples were determined by fluid invasion methods, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and 13C nuclear magnetic resonance (13C NMR) spectroscopy. Moreover, molecular-scale models were constructed to simulate the adsorption–desorption-diffusion performance of the gases in the surfactant-modified coal. As per the results, modification with methyltrimethoxysilane (MTMS) and polyethylene oxide (PEO) surfactants reduced the proportion of micropores and relative content of oxygen functional groups, resulting in reduced the adsorption of gases and enhanced diffusion performance, consistent with molecular simulations result. These results provide a theoretical foundation for elucidating the adsorption–desorption mechanisms of surfactant-treated coal and its application in mining areas.

Polydimethylsiloxane Surface Modification of Microfluidic Devices for Blood Plasma Separation.

Over the last decade, researchers have developed a variety of new analytical and clinical diagnostic devices. These devices are predominantly based on microfluidic technologies, where biological samples can be processed and manipulated for the collection and detection of important biomolecules. Polydimethylsiloxane (PDMS) is the most commonly used material in the fabrication of these microfluidic devices. However, it has a hydrophobic nature (contact angle with water of 110°), leading to poor wetting behavior and issues related to the mixing of fluids, difficulties in obtaining uniform coatings, and reduced efficiency in processes such as plasma separation and molecule detection (protein adsorption). This work aimed to consider the fabrication aspects of PDMS microfluidic devices for biological applications, such as surface modification methods. Therefore, we studied and characterized two methods for obtaining hydrophilic PDMS surfaces: surface modification by bulk mixture and the surface immersion method. To modify the PDMS surface properties, three different surfactants were used in both methods (Pluronic® F127, polyethylene glycol (PEG), and polyethylene oxide (PEO)) at different percentages. Water contact angle (WCA) measurements were performed to evaluate the surface wettability. Additionally, capillary flow studies were performed with microchannel molds, which were produced using stereolithography combined with PDMS double casting and replica molding procedures. A PDMS microfluidic device for blood plasma separation was also fabricated by soft lithography with PDMS modified by PEO surfactant at 2.5% (v/v), which proved to be the best method for making the PDMS hydrophilic, as the WCA was lower than 50° for several days without compromising the PDMS's optical properties. Thus, this study indicates that PDMS surface modification shows great potential for enhancing blood plasma separation efficiency in microfluidic devices, as it facilitates fluid flow, reduces cell aggregations and the trapping of air bubbles, and achieves higher levels of sample purity.

What is the role of PEO chains in the assembly of core-corona supraparticles in aqueous dispersions?

Hypothesis The assembly of core-corona supraparticles in aqueous dispersions has been regularly assisted by auxiliary monomers/oligomers which modify the individual particles with, e.g., surface grafting of polyethylene oxide (PEO) chains or other hydrophilic monomers. However, this modification complicates the preparation and purification procedures and increases potential upscaling efforts. Hybrid polymer-silica core-corona supracolloids could be more simply assembled if the PEO chains from surfactants, typically used by default as polymer stabilizers, concomitantly act as assembly promotors. The supracolloids assembly could therefore be more easily achieved without requiring particles functionalization or post-purification steps. Methods The self-assembly of supracolloidal particles prepared with PEO-surfactant stabilized (Triton X-405) and/or PEO-grafted polymer particles is compared to differentiate the roles of the PEO chains in the assembly of core-corona supraparticles. Using time-resolved dynamic light scattering (DLS) and cryogenic transmission electron microscopy(cryo-TEM), the effect of concentration of PEO chains (from surfactant) on the kinetics and dynamics of supracolloids assembly is investigated. Self-consistent field (SCF) lattice theory was used to numerically study the distribution of PEO chains at the interfaces present in the supracolloidal dispersions. Findings The PEO based surfactant can be used as assembly promoter of core-corona hybrid supracolloids due to its amphiphilic nature and via establishing hydrophobic interactions. The concentration of the PEO surfactant, and especially the PEO chains distribution over the different interfaces, crucially affect the supracolloids assembly. A simplified pathway for preparing hybrid supracolloidal particles with a well-controlled corona coverage over polymer cores is presented.

Computational and Experimental Models of Type III Lipid-Based Formulations of Loratadine Containing Complex Nonionic Surfactants.

Type III lipid-based formulations (LBFs) combine poorly water-soluble drugs with oils, surfactants, and cosolvents to deliver the drugs into the systemic circulation. However, the solubility of the drug can be influenced by the colloidal phases formed in the gastrointestinal tract as the formulation is dispersed and makes contact with bile and other materials present within the GI tract. Thus, an understanding of the phase behavior of LBFs in the gut is critical for designing efficient LBFs. Molecular dynamics (MD) simulation is a powerful tool for the study of colloidal systems. In this study, we modeled the internal structures of five type III LBFs of loratadine containing poly(ethylene oxide) nonionic surfactants polysorbate 80 and polyoxyl hydrogenated castor oil (Kolliphor RH40) using long-timescale MD simulations (0.4-1.7 μs). We also conducted experimental investigations (dilution of formulations with water) including commercial Claritin liquid softgel capsules. The simulations show that LBFs form continuous phase, water-swollen reverse micelles, and bicontinuous and phase-separated systems at different dilutions, which correlate with the experimental observations. This study supports the use of MD simulation as a predictive tool to determine the fate of LBFs composed of medium-chain lipids, polyethylene oxide surfactants, and polymers.

Aqueous phase behavior of the PEO-containing non-ionic surfactant C12E6: A molecular dynamics simulation study

HypothesisNon-ionic surfactants containing polyethylene oxide (PEO) chains are widely used in drug formulations, cosmetics, paints, textiles and detergents. High quality molecular dynamics models for PEO surfactants can give us detailed, atomic-scale information about the behavior of surfactant/water mixtures. SimulationsWe used two molecular dynamics force fields (FFs), 2016H66 and 53A6DBW, to model the simple non-ionic PEO surfactant, hexaoxyethylene dodecyl ether (C12E6). We investigated surfactant/water mixtures that span the phase diagram of starting from randomly distributed arrangements. In some cases, we also started with prebuilt, approximate models. The simulations results were compared with the experimentally observed phase behavior. FindingsOverall, this study shows that the spontaneous self-assembly of PEO non-ionic surfactants into different colloidal structures can be accurately modeled with MD simulations using the 2016H66 FF although transitions to well-formed hexagonal phase are slow. Of the two FFs investigated, the 2016H66 FF better reproduces the experimental phase behavior across all regions of the C12E6/water phase diagram.

Electrospinning pectin-based nanofibers: a parametric and cross-linker study

Pectin, a natural biopolymer mainly derived from citrus fruits and apple peels, shows excellent biodegradable and biocompatible properties. This study investigated the electrospinning of pectin-based nanofibers. The parameters, pectin:PEO (polyethylene oxide) ratio, surfactant concentration, voltage, and flow rate, were studied to optimize the electrospinning process for generating the pectin-based nanofibers. Oligochitosan, as a novel and nonionic cross-liker of pectin, was also researched. Nanofibers were characterized by using AFM, SEM, and FTIR spectroscopy. The results showed that oligochitosan was preferred over Ca2+ because it cross-linked pectin molecules without negatively affecting the nanofiber morphology. Moreover, oligochitosan treatment produced a positive surface charge of nanofibers, determined by zeta potential measurement, which is desired for tissue engineering applications.

Graphene–polyelectrolyte multilayer film formation driven by hydrogen bonding

A method for preparing hydrogen bonded multilayer thin films comprised of layer pairs of surfactant stabilized graphene and an anionic polyelectrolyte is described. The films were constructed at low pH using the Layer-By-Layer (LbL) technique, where the adsorption of the cationic polyelectrolyte, polyethyleneimine (PEI) is followed by the sequential alternating adsorption of the anionic polyelectrolyte, polyacrylic acid (PAA) and anionic graphene sheets modified with Pluronic® F108, a polyethylene oxide–polypropylene oxide–polyethylene oxide (PEO–PPO–PEO) surfactant. Quartz Crystal Microbalance (QCM) measurements indicate that film formation was driven by hydrogen bonding between the carboxylic acid group of the PAA and ethylene oxide unit present in the surfactant. QCM measurements and Raman spectra showed evidence of non-linear and linear growth at low and high numbers of adsorbed layers respectively, suggesting overall superlinear film growth. Atomic Force Microscopy (AFM) Quantitative Nanomechanical Mapping (QNM) measurements of the films indicated that the reduced Young’s Modulus of the films decreased with increasing numbers of adsorbed layers, reaching a bulk value of 6.07–32.3MPa for samples with greater than 300 layers of surfactant stabilized graphene and PAA. The films were also shown to deteriorate partially with aqueous solutions at neutral and basic pH. The thin films exhibited features advantageous for use in coatings, such as pH responsiveness in addition to different mechanical properties, surface roughness, and internal structures based on the number of layers adsorbed.

Layer-by-Layer Assembly of Thin Films Containing Exfoliated Pristine Graphene Nanosheets and Polyethyleneimine

A method for the modification of surface properties through the deposition of stabilized graphene nanosheets is described. Here, the thickness of the film is controlled through the use of the layer-by-layer technique, where the sequential adsorption of the cationic polyethyleneimine (PEI) is followed by the adsorption of anionic graphene sheets modified with layers of polyethylene oxide-polypropylene oxide-polyethylene oxide (PEO-PPO-PEO) surfactants. The graphene particles were prepared using the surfactant-assisted liquid-phase exfoliation technique, with the low residual negative charge arising from edge defects. The buildup of the multilayer assembly through electrostatic interactions was strongly influenced by the solution conditions, including pH, ionic strength, and ionic species. Thereby, not only could the thickness of the film be tailored through the choice of the number of bilayers deposited but the viscoelastic properties of the film could also be modified by changing solution conditions at which the different species were deposited. The quartz crystal microbalance was used to measure the mass of graphene and polyelectrolyte immobilized at the interface as well as to probe the energy dissipated in the adsorbed layer.

ChemInform Abstract: Chemical Drug Stability in Lipids, Modified Lipids, and Polyethylene Oxide‐Containing Formulations

AbstractReview: 44 refs.

Chemical Drug Stability in Lipids, Modified Lipids, and Polyethylene Oxide-Containing Formulations

To critique the stability complications seen in formulating poorly water-soluble, problematic drugs in lipids, modified lipids, and polyethylene oxide solvents and surfactants in hard and soft gelatin capsules as well as some parenterals, a literature search was performed and personal experiences, and those of colleagues, collated. The literature is replete with examples of molecules undergoing rapid oxidative degradation in the presence of polyethylene oxide based solvents and surfactants as well as in the presence of unsaturated lipids. More recently appreciated is instability caused by the reaction of amine and amide drugs, with formaldehyde, formic acid found in many of these solvents as impurities and other degradation byproducts of the solvents themselves. One would expect acylation and transacylation reactions to be more common than reported but the literature has some good examples. An added complexity is occasionally seen with the use of hard and soft gelatin capsules with these solvents. The chemical stability of drugs in liquid and semi-solid formulations in the presence of lipids, modified lipids, and polyoxyethylene oxide-based solvents and surfactants can be complex, further exacerbated by the use of gelatin capsules, and can lead to a plethora of degradation pathways often not seen when the same drugs are formulated in solid dosage forms.

Synthesis of organic–inorganic hybrid MSU-1 for separation and catalytic applications

A series of spherical hybrid MSU-1 composed of homogeneously distributed ethane groups in a silica framework was prepared via the twostep sol–gel process using 1,2-bis(triethoxysilyl)ethane (BTEE) in a nonionic alkyl polyethylene oxide (Tergitol 15-S-12) surfactant solution. Hydrolysis of BTEE was conducted in acidic condition at room temperature and condensation of silicate species was promoted by F − catalyst at 65 °C. The hybrid MSU-1 products synthesized were characterized by XRD, N 2 adsorption/desorption isotherm, TGA, SEM, and TEM after solvent extraction. The materials were made of wormhole-like mesopore structures, and surface area, pore volume, and pore diameter increased with the concentration of NaF (NaF/BTEE = 0.03–0.15) and temperature (35–65 °C). Incorporation of the organic fraction was confirmed by 29Si and 13C CP MAS NMR. The hybrid MSU-1, after C 8 grafting and end-capping, demonstrated a good performance as a stationary phase in chromatography. The hybrid MSU-1-supported palladium material also showed excellent catalytic performances in Sonogashira cross-coupling reactions of aryl iodide with phenylacetylene.

Analysis of neutral surfactants by non-aqueous medium capillary electrophoresis hyphenated to mass spectrometry (ion trap)

Non-derivatized Brij 58 oligomers were analyzed by using non-aqueous capillary electrophoresis (NACE) hyphenated to mass spectrometry (ion trap). The separation of this neutral polyethylene oxide surfactant was based on its complexation with ammonium cation in methanolic medium. Cationic complexes were formed within the capillary and migrated against the anodic electroosmotic flow. The latter was obtained by using a pre-treatment of the capillary with hexadimethrine bromide. By optimizing mass detection and the separation conditions separately, it was demonstrated that two different salts had to be used. Ammonium acetate was used in the sheath liquid to optimize detection sensitivity whereas ammonium iodide was used in the running electrolyte in order to obtain the more appropriate electroosmotic flow for the separation. Despite an aspiration effect due to the hyphenation with MS. that did not allow us to obtain a baseline resolution for the entire mixture, we were able to visualize and characterize more than 25 oligomers of Brij 58. As regards detection sensitivity, the limits of detection (LOD) were estimated at about 7.5 ng for the entire distribution of Brij 58 and 15 pg for C 16E 5 or C 16E 6 used as standards.

Morphology control of MSU-1 silica particles

Mesoporous silica, MSU-1 with spherical morphology was prepared using TEOS (tetraethylorthosilicate) as a silica source in the presence of an alkyl polyethylene oxide surfactant via the novel two-step process proposed by Prouzet’s group: hydrolysis of TEOS conducted in highly acidic condition at room temperature followed by condensation promoted by fluoride salt addition at 35 °C. The particles produced were characterized by XRD, SEM, and N 2 adsorption/desorption isotherm. Static condensation period was found to be essential to have spherical morphology. Growth of spherical particles and evolution of porosity were studied as a function of time, temperature, NaF/TEOS, and TEOS/surfactant ratio. The MSU-1 particles prepared under different synthesis conditions were briefly tested for chromatographic separation of selected organic molecules, which demonstrates the governing influence of the pore size in MSU-1 on retention time.

Correlation Between Epithelial Toxicity and Surfactant Structure as Derived From the Effects of Polyethyleneoxide Surfactants on Caco-2 Cell Monolayers and Pig Nasal Mucosa

The cell toxic effects of nonionic surfactants were investigated by means of two in vitro models, namely pig nasal mucosa mounted in horizontal Ussing chambers, and Caco-2 cell monolayers. A series of homologous polyethyleneoxide (PEO) surfactants with a wide span in hydrophilic head-group size and hydrophobic chain lengths were screened for concentration-dependent effects on the transepithelial electrical resistance (TEER) and mannitol permeability across Caco-2 cell monolayers. Trends in effects on permeability in the presence of increasing surfactant concentration coincided with the effects seen on TEER. Correlation of surfactant molecular structure with cell toxicity showed the size of the PEO group to be a more critical parameter than the size of the hydrocarbon chain. More specifically, the presence of very long PEO groups (>30 EO units) were found to lead to a decrease in cell toxicity. Similar trends were observed in the studies of the effects of PEO surfactants on pig nasal mucosa mounted in horizontal Ussing chambers. However, the nasal mucosa was somewhat more tolerant towards high surfactant concentrations than the Caco-2 cells. The relation between surfactant molecular structure and cell toxic effects is discussed in terms of micellar surface adsorption and micellar solubilization. The effect of the surfactants on the solubility of budesonide was investigated at two different surfactant concentrations (0.01 and 1 mg/mL). At the lower concentration, the solubilizing capacity of all of the surfactants was marginal, and there was no correlation between solubilizing capacity and cmc. At the higher concentration, on the other hand, all surfactants substantially increased the solubility of budesonide. The C18 PEO-ester with 40 EO units in the head group was found to be an efficient micellar solubilizer for budesonide, without causing adverse effects on the Caco-2 cell monolayers.

Synthesis of acicular goethite with surfactants

Goethite nanotubes have been synthesised using polyethylene oxide (PEO) surfactant as a directing agent. The surfactant enables the goethite to crystallise along a specific pathway and does not affect the crystal structure of the mineral but rather the agglomeration of the mineral. The crystals reach an optimum size at which the surfactant can bond.

The characterization and photocatalytic properties of mesoporous rutile TiO 2 powder synthesized through self-assembly of nano crystals

Mesoporous titania with an average pore diameter of 2.6 nm and rutile crystalline structural wall was prepared by hydrolyzing TiOCl 2 aqueous solution at lower temperature by using octyl polyethylene oxide surfactant as template-directing agent. The mesoporous structure of as-synthesized mesoporous rutile titania consisting of self-assembled nano crystals keeps stable after the removal of the surfactant by acetone extraction and following UV irradiation. The mesoporous rutile titania exhibits a good photocatalytic activity for gas-phase photo-oxidation of a mixture of benzene and methanol. A mechanism of self-assembly of nano titania crystals is proposed to explain the formation of mesoporous rutile titania.

Hierarchical microtubular nanoporous zirconia with an extremely high surface area and pore volume

Hierarchical nanoporous zirconias with an aligned microtubular structure of inner diameter 0.5–1.5 μm and length 5–30 μm and an extremely high surface area and large pore volume (up to 1100 m 2/g and 3.0 cm 3/g, respectively) have been prepared by a simple method from a mixture of zirconium propoxide and chloroform solutions in the presence of nonionic polyethylene oxide surfactant. The tubular walls are composed of wormhole-like nanopores, resulting in very high surface areas and large pore volumes of hierarchical porous materials for multi-applications.

Hierarchically mesoporous/macroporous metal oxides templated from polyethylene oxide surfactant assemblies.

Hierarchically mesoporous/macroporous metal oxides templated from polyethylene oxide surfactant assemblies.

Hierarchically Mesoporous/Macroporous Metal Oxides Templated from Polyethylene Oxide Surfactant Assemblies

Hierarchically Mesoporous/Macroporous Metal Oxides Templated from Polyethylene Oxide Surfactant Assemblies

Molecular engineered porous clays using surfactants

Quaternary ammonium surfactants were used to control the pore structure of bentonite intercalated with a mixed hydro-sol of silicon and titanium. Porous clay heterostructures of alumina and laponite were prepared in the presence of polyethylene oxide (PEO) surfactants. Participation of the surfactants in the synthesis results in significant changes in the structure of porous clay products. Surfactants are involved in different mechanisms. In the case of bentonite, the mean size of the framework pores was directly proportional to the chain length of the quaternary ammonium surfactants. This indicates a molecular templating mechanism, similar to that observed in the synthesis of MCM41. However, in the case of laponite, the size and volume of the mesopores were related to the amount of PEO surfactants used. By using an appropriate surfactant, we can obtain highly porous clays with various pore structures. Introducing surfactants during intercalation is an efficient strategy for the molecular engineering of porous clay adsorbents and catalysts.