Dodecyltrimethylammonium Bromide Research Articles

Stimulated Pickering emulsion stabilized by binary particles with contrasting wettability and trace surfactant

The investigationof self-assembled particle structures at fluid interfaces has gained considerable interest across various fields. In particular, Pickering emulsions (PEs) stabilized by binary particles co-assembling at these interfaces have attracted even more attention. To explore the self-assembly process of superhydrophobic and superhydrophilic particles at oil–water (O/W) interfaces influenced by a trace amount of surfactant, a series of experiments were conducted. A small quantity (0.01 mmol·L−1) of dodecyltrimethylammonium bromide (DTAB) was introduced, establishing a variable stable emulsion system with high salt tolerance, capable of withstanding up to 6 mol·L−1 NaCl, in synergism with the particles. The DTAB concentration required to stabilize the O/W emulsion with particles was as low as 0.001 mmol·L−1. The stability and type of the resulting emulsion could be adjusted by varying the ratio of hydrophobic to hydrophilic particle (R) or by modifying acid/base conditions. The systems exhibited robust cyclic acid/base regulated demulsification and phase inversion behavior, maintaining stability over at least 10 cycles. Results indicated that the stability and nature of the emulsion were influenced by the curvature of the interface formed by the self-assembled interfacial particle structures, arising from the competitive adsorption of both types of particles and trace surfactant. Further analysis revealed a correlation between interfacial curvature and the surface charges of the particles, which could be modulated through DTAB adsorption. This study elucidated the behavior of hydrophilic and hydrophobic particle self-assembly at interfaces, provided a straightforward strategy for co-preparing switchable emulsions using superhydrophilic and superhydrophobic particles, and expanded the range of amphiphilic particles available for producing PEs. This approach presents significant potential for future research and applications in the field of PEs.

Inhibition of Polyphenol Oxidase Activity by Mesoporous Silica Nanoparticles and Multiwalled Carbon Nanotubes Modified with Surfactants.

Polyphenol oxidase (PPO) is the culprit behind the browning of fruits and vegetables. Therefore, how to reduce the thermal deactivation temperature of PPO or use as few safe reagents as possible to inhibit enzymatic browning has practical significance. Mesoporous silica nanoparticles (MSNs) and multiwalled carbon nanotubes (MWCNTs) are stable and have high biosafety. In the present study, efficient PPO inhibitors were developed based on MSNs and MWCNTs. It is found that after modification with a very small amount of dodecyl trimethylammonium bromide (DTAB, ≥60 μg/mL), MSNs can significantly inhibit the activity of PPO although single MSNs and single DTAB show very limited effect on PPO activity. After modification with a very small amount of sodium dodecyl sulfate (SDS, 5.7-9.5 μg/mL), MWCNTs almost completely inactivate PPO. However, SDS@MSN and DTAB@MWCNT cannot decrease PPO activity significantly.

Remediation of hexavalent chromium in water and soil by pristine and chemically modified pine barks: Effects and mechanisms

Chemical modification can greatly improve the adsorption performance of materials. In this study, pristine pine bark (PB) was modified by phosphoric acid (PA-PB), dodecyl trimethylammonium bromide (DTAB-PB) and cetyl trimethylammonium bromide (CTAB-PB) to test their influence on remediating hexavalent chromium [Cr(Ⅵ)] contamination in water and soil systems. Under the optimal experimental conditions in solution, the reduction/adsorption capacities and removal rates of Cr(Ⅵ) follow the order of CTAB-PB > PA-PB > DTAB-PB > PB, with CTAB-PB showing the highest capacity of 88.1 mg g−1. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Photoelectron Spectroscopy (XPS) indicated that adsorption coupled with reduction were the responsible mechanisms for Cr(Ⅵ) removal by pristine and modified PB, and modification with CTAB greatly improved Cr(Ⅵ) removal, especially the reduction of Cr(Ⅵ). When CTAB-PB and PB were applied in soil for a 30-day microcosm experiment, more than 93 % of Cr(Ⅵ) was converted into Cr(Ⅲ) at four different addition levels (2, 5, 10, and 15 wt%) with CTAB-PB exhibiting a faster immobilization rate than PB. In conclusion, CTAB-PB showed better performance than PB and is a promising material for the remediation of Cr(Ⅵ) contamination in water and soil.

Supraparticles from Cubic Iron Oxide Nanoparticles: Synthesis, Polymer Encapsulation, Functionalization, and Magnetic Properties.

Supraparticles (SPs) consisting of superparamagnetic iron oxide nanoparticles (SPIONs) are of great interest for biomedical applications and magnetic separation. To enable their functionalization with biomolecules and to improve their stability in aqueous dispersion, polymer shells are grown on the SPs' surface. Robust polymer encapsulation and functionalization is achieved via atom transfer radical polymerization (ATRP), improving the reaction control compared to free radical polymerizations. This study presents the emulsion-based assembly of differently sized cubic SPIONs (12-30 nm) into SPs with diameters ranging from ∼200 to ∼400 nm using dodecyltrimethylammonium bromide (DTAB) as the surfactant. The successful formation of well-defined spherical SPs depends upon the method used for mixing the SPION dispersion with the surfactant solution and requires the precise adjustment of the surfactant concentration. After purification, the SPs are encapsulated by growing surface-grafted polystyrene shells via activators generated by electron transfer (AGET) ATRP. The polymer shell can be decorated with functional groups (azide and carboxylate) using monomer blends for the polymerization reaction. When the amount of the monomer is varied, the shell thickness as well as the interparticle distances between the encapsulated SPIONs can be tuned with nanometer-scale precision. Small-angle X-ray scattering (SAXS) reveals that cubic SPIONs form less ordered assemblies within the SPs than spherical SPIONs. As shown by vibrating sample magnetometer measurements, the encapsulated SPs feature the same superparamagnetic behavior as their SPION building blocks. The saturation magnetization ranges between 10 and 30 emu/g and depends upon the nanocubes' size and phase composition.

Effect of Methyl Red on the surface properties of DTAB in CH3OH–H2O

The purpose of this study is to investigate the effect of Methyl Red (MR) on the micellization and surface properties of a cationic surfactant, dodecyl trimethylammonium bromide (DTAB), in CH3OH–H2O mixed solvent systems at varying CH3OH parts by volumes (0.1, 0.2, 0.3, and 0.4) and temperatures (298.15 K, 308.15 K and 318.15 K). Surface tension and conductivity measurements were conducted to obtain the critical micelle concentration (CMC) and various surface properties such as premicellar slope (dγdlogC), maximum surface concentration (Γmax), minimum surface area occupied (πCMC), free energy of adsorption (ΔGadso), adsorption efficiency (pC20), packing parameter (P), and aggregation number (Nagg). The results indicate that the presence of MR significantly influences the behavior of DTAB in the mixed solvent system. In the absence of MR, the CMC increased with higher CH3OH content, while MR reduced the CMC, promoting micelle formation through dye-surfactant-ion-pair (DSIP) formation. Surface properties were enhanced in the presence of MR leading to higher surface pressure. Additionally, the free energy of adsorption (ΔGadso) became more negative with MR, indicating a more favorable adsorption process. Correlations of (dγdlogC), Γmax,γ0/γcmc, pC20, Nagg, CMC/C20 with the parts by volume of CH3OH at 298.15 K, 308.15 K, and 318.15 K are discussed with and without MR. The obtained results were used to examine the effect of MR on the surface properties of DTAB in the CH3OH–H2O medium. The change in properties can be explained in terms of the change in polarity of the medium and dye-surfactant ion pair (DSIP) formation.

Synthesis of silica-coated polygonal Fe3O4 nanoparticles

The small size, surface effect, and tunneling effect of nanomaterials enable their applications in various fields, including catalysis, sensing. Fe3O4 has been widely used in nanotechnology owing to its excellent photoelectromagnetic properties. In this study, polygonal Fe3O4 nanoparticles were prepared through a high-temperature synthesis method. Subsequently, silica coating was applied via the Stöber method to obtain a nanomaterial with uniform particles. The prepared Fe3O4 exhibited a distinct crystal structure and an ultra-high saturation magnetization, reaching up to 134.2 emu/g. Moreover, the dodecyl trimethyl ammonium bromide (DTAB) templating agent facilitated the coating of Fe3O4 with silica. The coated Fe3O4@SiO2 particles featured a well-defined core–shell structure and corrosion resistance, making them highly promising candidates for magnetic targeting medical tools, magnetic resonance imaging agents and other biological applications.

Highly sensitive colorimetric detection of Cd(ii) based on silica sol modified with dithizone and cationic surfactant.

The cadmium ion (Cd2+) is highly poisonous and nondegradable and easily bioaccumulates through the food chain. Therefore, it is crucial to develop cost-effective chemical sensors for Cd2+ with fast response time, high selectivity, and very low detection limits. In this study, a colorimetric sensor for the determination of Cd2+ was fabricated by modifying silica sol with dodecyltrimethylammonium bromide (DTAB) and dithizone (DZ). Cd2+ formed a complex with DZ, changing the solution color immediately from purple to orange prior to detection using ultraviolet-visible spectrophotometry and a customized Cd analyzer for the precipitate. Under the optimum conditions, the developed Cd2+ sensor had a linear range of 0.01-0.25 mg L-1, a low limit of detection of 5.0 μg L-1, and outstanding repeatability. This sensor also showed good precision, with the relative standard deviations of less than 2.59% and 3.24% for the intra- and inter-day data, respectively. The proposed colorimetric method was successfully applied to determine Cd2+ in environmental water samples, and the results were comparable to those obtained using standard atomic absorption spectrometry. Moreover, quantitative analysis was conducted using the customized Cd analyzer to estimate the color intensity change, without requiring sophisticated scientific instruments. This colorimetric sensor can be used for the portable, cost-effective, and rapid on-site detection of Cd2+ in environmental water samples.

Monolayer instability of ionic surfactants at the water/air interface due to biosurfactant molecules: A molecular dynamic approach

The decomposition of monolayers prepared with anionic surfactants, sodium dodecyl sulfate (SDS), or cationic ones, dodecyltrimethylammonium bromide (DTAB), at the water/air interface was studied when biosurfactants (surfactin) are added to the films. Molecular dynamics simulations were carried out for monolayers with a fixed number of SDS or DTAB molecules and a different amount of biosurfactants to form SDS/surfactin and DTAB/surfactin mixtures. It is found that the presence of the biosurfactant modifies interfacial and structural properties of the ionic monolayers at the interface; the DTAB monolayer is distorted even for a few surfactin molecules, whereas the SDS monolayer remains steady up to a given amount of biosurfactant. In both monolayers the surface tension decreases with the number of biosurfactants, however while for the DTAB/surfactin the values seem to fluctuate, for the SDS/surfactin mixture the values decay linearly, with a discontinuity for a given surfactin concentration. The linear behaviour of the surface tension for the SDS/surfactin allows us to evaluate free energies for the monolayers and a two-dimensional equation of state. The structure of the monolayers was analyzed in terms of density profiles, order parameters, thickness of the interfaces and the data show that the DTAB/surfactin is more distorted than the SDS/surfactin by the presence of few surfactin molecules. The results indicate that SDS surfactants are more likely to form longer lasting films with fewer surfactin molecules than DTAB.

Preparation of Mesoporous Analcime/Sodalite Composite from Natural Jordanian Kaolin

In this work, a meso-macroporous analcime/sodalite zeolite composite was produced by a hybrid synthesis process between a complex template method and hydrothermal treatment at 220 °C of naturally abundant kaolinitic-rich clay, using dodecyltrimethylammonium bromide as an organic soft template to enhance the mesoporous structure. The chemical and morphological properties of the developed zeolites composite were characterized using powder X-ray diffraction (PXRD), attenuated total Reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), thermogravimetric analysis (TGA), N2 adsorption/desorption; and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) methods were used to study the morphology, chemical composition and structure of the product. Two types of zeolite particles were obtained:(1) hollow microsphere with an attached analcime icositetrahedron of 30–40 µm in size and (2) sodalite microsphere with a ball-like morphology of 3–4 µm in size. Both N2 adsorption/desorption and surface area data confirmed the high potentiality of the produced zeolite composite to act as an excellent adsorbent to remove inorganic pollutants such as Cu, Cd, Cr, Ni, Zn, and Pb ions, organic pollutants such as dyes, phenolic compounds, and surfactants from water; and their high catalytic activity, especially in the oxidation reaction of volatile organic compounds. The catalytic activity and adsorption ability of the produced analcime/sodalite composite will be tested experimentally in future work.

Quantitative evaluation of the difference in residual collectors in sulfide and non-sulfide flotation processes

In this study, three separate flotation systems were studied to define the residual collectors found in different recycled water for sulfide (xanthate-chalcopyrite), non-sulfide with anionic (NaOL-dolomite) and cationic (DTAB-quartz) collector processes. The adsorption/desorption of collectors and the adsorption morphology were studied by the zeta potential and atomic force microscopy (AFM) measurements, the adsorption energy and configurations were simulated by the density functional theory-based first principal calculations. It was found that butyl xanthate (BX) was adsorbed on chalcopyrite surface with pronounced protrusions by chemisorption, and the residual BX in slurry was 5.79 %. While sodium oleate (NaOL) formed scattered protrusions on dolomite surface by weak adsorption, the residual NaOL in slurry was 30.74 % that reacted with the Ca2+ or Mg2+ cations. The dodecyl trimethyl ammonium bromide (DTAB) adsorbed on quartz surface through hydrophobic aggregations and the residual DTAB in slurry was 16.57 %. This work might provide a guidance for understanding reagent consumption and flotation performance in typical mineral flotation systems.

Organo magadiites for diclofenac adsorption: influence of the surfactant chain.

The presence of drugs in aquatic environments has been considered a global challenge and several remediation technologies have been proposed, including adsorption. In this study, new diclofenac adsorbents were obtained from the reaction of sodium magadiite (Na-Mag) with surfactants dodecylpyridinium chloride hydrate (C12pyCl) and hexadecylpyridinium chloride monohydrate (C16pyCl)), 1-hexadecyltrimethylammonium bromide (C16Br), and dodecyltrimethylammonium bromide (C12Br). The synthesis was carried out in the microwave at 50°C for 5min using surfactant amounts of 100% and 200% in relation to the cation exchange capacity of Na-Mag. The elemental analysis indicated that surfactants with a longer organic chain were more incorporated into Na-Mag, whose values were 1.42 and 1.32mmolg-1 for C16pyMag200% and C16Mag200%, respectively. X-ray diffraction results suggested formation of intercalated products with basal space in the range of 2.81-4.00nm. Diclofenac was quickly adsorbed on all organophilic magadiites, at an equilibrium time of 1min. Drug capacity adsorption was influenced by the arrangement and packing density of organic cations, the basal distance, and the organic contents of the samples at high drug concentrations. Alkylpyridinium magadiites exhibited maximum adsorption capacities higher than alkylammonium magadiites, of 96.4, 100.7, 131.7, and 166.1mgg-1 for C12pyMag100%, C12pyMag200%, C16pyMag100%, and C16pyMag200%, respectively, at pH 6.0 and 30°C. Diclofenac removal by samples was not affected by the presence of ibuprofen, which was also removed from binary system by organophilic magadiites reaching removal of 76.5% and 86.9% by C16pyMag100% and C16pyMag200%, respectively. Regeneration studies demonstrated a drug removal percentage of 83-92% for C16pyMag and C16Mag after three cycles of adsorption.

Investigation on the flotation of a mixed collector and its mechanism for enhancing low-rank coal flotation: Effect of micro adsorption and its interaction with gangue particle

The flotation effect of the association formed by dodecyl trimethyl ammonium bromide (DTAB) and dodecyl alcohol polyoxyethylene ether sodium sulfate (AES), and nonpolar kerosene mixed collectors on low-rank coal (LRC) was investigated. The results show that the combustible matter recovery was significantly improved compared with a single kerosene from 49.88% to 74.97% when the the mixed collector was used, while concentrate ash content decreased from 9.76% to 8.57% simultaneously. The utilization of the mixed collector not only enhanced the surface hydrophobicity of organic particles but also facilitated the intercoalescence among them, thereby reducing the ash content of concentrate during flotation. The molecular dynamics simulation (MDS) results show that the effect of the mixed collector on the surface of LRC is mainly the electrostatic interaction and hydrogen bonding between the collector molecules and the surface molecules of LRC, which makes the polar molecules in the collector closely adsorbed on the surface of LRC.

Photophysical Response of Propranolol in Biomimetic Micellar Media of Alkyltrimethylammonium Bromide Surfactants: Effect of pH and Alkyl Chain Length.

The photophysical behavior of a β-blocker drug propranolol (PPL) in micellar environments, formed by alkyltrimethylammonium bromide surfactants viz.; Cetyltrimethylammonium bromide (CTAB), Tetradecyltrimethylammonium bromide (TTAB), and Dodecyltrimethylammonium bromide (DTAB), has been investigated through fluorescence and UV-visible spectroscopic techniques at pH levels of 3.5, 7.4, and 10.4. The impact of pH on the critical micelle concentration (cmc) and micropolarity of micelles were assessed using pyrene as a photophysical probe. The cmc values were found to be lower at pH 10.4 compared to pH 7.4 and pH 3.5. Fluorescence emission intensities of PPL at 323nm, 338nm, and 352nm were significantly influenced by pH, hydrophobic alkyl chain length of surfactants, and their concentrations. Quenching experiments with Cetylpyridinium chloride (CpCl) indicated the localization of charged and uncharged forms of PPL within micelles, with quenching constant (Ksv) values dependent on alkyl chain length and pH. At pH < pKa, PPL is positioned near the Stern layer, whereas at pH 10.4, its naphthalene moiety resides near the hydrophobic micellar core. UV spectroscopy showed that the charged form of PPL interacted with micelles only above cmc, while the neutral form interacted even below the cmc. Density Functional Theory (DFT) reveals the HOMO of the surfactants to be localized on the hydrocarbon chains, and the LUMO localized around the quaternary ammonium unit. Upon complexation with PPL, both HOMO and LUMO shifted to the drug, thereby decreasing energy levels. The findings are explained based on weak noncovalent interactions, further supported and analyzed through Reduced Density Gradient (RDG) and Noncovalent Interaction (NCI) methods, confirming synergistic non-covalent interactions in surfactant-PPL complexes.

Microstructure evolution and mechanical behavior of foamed cement-based tail backfills under varying fiber types and concentrations.

Industrial solid waste (mine tailings) management has emerged as the key universal ecological challenge as a result of the unceasing creation of rising waste by-products. Employing tailings makes mine fill production economical and assists resolve disposal problems. Foamed cement-based tailings backfill (FCTB) is a mine fill consisting of tailing, cement, water, and foaming agents. It provides certain advantages such as lightweight, good fluidity, and thermal insulation yet is relatively weak in strength. Additionally, FCTB's strength properties can be intensely improved by adding fibers. A total of three diverse fibers: polypropylene (PP), glass (G), and basalt (B) as well as dodecyltrimethylammonium bromide (DTAB) as a foaming agent were used to prepare fiber-reinforced foamed cementitious tailings backfill (FR-FCTB). The mechanical properties, energy evolution, ductility, and microstructure of FR-FCTB were elaborately investigated by uniaxial compression tests (UCS) and SEM. Laboratory findings demonstrate the reinforcing effect of three fibers on FCTB specimens: glass > polypropylene > basalt. FR-FCTB showed the best strength features as a fiber content of 0.3% was adopted in FCTB. At this time, the UCS performance of glass fiber-reinforced FCTBs was 0.85MPa increased by 18.1%. The addition of fibers can increase the fill's energy storage limit, slow down the discharge of elastic strain energy within the backfill, and enhance the fill's ductility and toughness. The ductility factor evaluates the degree of deterioration of filling in terms of post-peak drop, with all FR-FCTB values being greater than CTB. FR-FCTB's chief hydration product is the C-S-H gel. Fiber's bridging effect significantly rallies crack extension and thus fill's strength features. Lastly, the study's main results are instructive for the industrial application of FR-FCTB used in metallic mines.

Supramolecular engineering of micellar systems: Precision control on self-assembly, polarity, and charge for enhanced nanocarrier design

In the quest for enhanced drug delivery systems, the combination of supramolecular receptors and surfactants represents a promising step toward developing innovative and highly efficient nanocarriers. This research highlights the paramount advantages of synergizing these elements, focusing on the manipulation of the self-assembly, charge, and polarity of the hybrid nanostructures resulting from merging these building blocks. In this vein, this work reveals that the integration of hexamethylated p-sulfonatocalix[6]arene (SC6A) and dodecyltrimethylammonium bromide (DTAB) offers significant advantages over those colloidal nanostructures stemming from the use of surfactant alone. These include the ability to stimulate early self-assembly, thereby facilitating the formation of stable nanocarriers, even in high-dilution scenarios. Additionally, the electrostatic balance established within the macrocycle-surfactant host–guest complexes can be harnessed to finely adjust the charge of the hydrophilic micellar corona. This holds great promise for modulating the bio-interaction capabilities of nanocarriers. Furthermore, the inclusion of the macrocycle in the colloidal structure induces significant alterations in the arrangement of low-molecular-weight surfactants. This leads to a significant transformation in the hydrophobic properties of the micellar core, which can be exploited to tailor this microenvironment to match the lipophilicity of specific drugs. In this regard, our findings reveal that while conventional DTAB micelles generally replicate the polarity of a solvent with a dielectric constant of 37.7, engineered SC6A-DTAB aggregates demonstrate a capability to reach a polarity akin to a solvent with dielectric constant of 17.5. This spectrum of hydrophobicities within the micellar core represents a significant advancement and opens up new possibilities for drug delivery applications.

Formation and survival of clay-mediated protocell membranes composed of single-chain amphiphiles in aqueous solutions

Protocell compartments composed of simple amphiphilic molecules could have survived on the clay mineral surfaces which can serve well as plausible sites for prebiotic chemistry on the early Earth. Herein we chose four common single-chain amphiphiles (SCAs), including the anionic surfactant sodium dodecyl sulfate (SDS) and sodium dodecylbenzenesulfonate (SDBS), the cationic surfactant dodecyltrimethylammonium bromide (DTAB) and the zwitterionic lauryl sulfobetaine (LSB)), as model constituents of early membranes to establish a tentative model for protocell compartment. Positively charged Mg2Al-/Mg2Fe-layered double hydroxides (LDHs) and FeS2 are viewed as models of clay minerals. We demonstrate by comprehensively experimental study that unconventional vesicles can be easily promoted in a SCA aqueous micellar solution in the presence of model particles. Morphology evolutions are traced by collecting samples from mixtures of LDHs and SCA aqueous solutions and then recording at different incubation times via negative-staining or cryo-transmission electron microscopy (NS-TEM or cryo-TEM) and dynamic light scattering (DLS). Additionally, the stability of SCA bilayer membranes under possible prebiotic environment are tentatively studied. This work not only offers a robust yet versatile approach for the fabrication of novel vesicles but also provides new insights into the origin of cellular life.

Surfactant-Mediated Microalgal Flocculation: Process Efficiency and Kinetic Modelling.

Microalgae are a valuable source of lipids, proteins, and pigments, but there are challenges in large-scale production, especially in harvesting. Existing methods lack proven efficacy and cost-effectiveness. However, flocculation, an energy-efficient technique, is emerging as a promising solution. Integrating surfactants enhances microalgal harvesting and disruption simultaneously, reducing processing costs. This study investigated cetyltrimethylammonium bromide (CTAB), dodecyltrimethylammonium bromide (DTAB), and sodium dodecyl sulphate (SDS) for harvesting Tetraselmis sp. strains (75LG and 46NLG). CTAB exhibits superior results, with 88% harvesting efficiency at 1500 and 2000 mg L-1 for 75LG and 46NLG, respectively, for 60 min of sedimentation-thus being able to reduce the operating time. Beyond evaluating harvesting efficiency, our study explored the kinetics of the process; the modified Gompertz model led to the best fit. Furthermore, the largest kinetic constants were observed with CTAB, thus highlighting its efficacy in optimising the microalgal harvesting process. With the incorporation of the suggested enhancements, which should be addressed in future work, CTAB could hold the potential to optimise microalgal harvesting for cost-effective and sustainable large-scale production, eventually unlocking the commercial potential of microalgae for biodiesel production.

An insight into physicochemical properties of hexagonal lyotropic liquid crystal templates from amphiphiles for mesoporous structural administration

Hexagonal lyotropic liquid crystals (HLLC) provide an ideal template for the fabrication of nanofiltration membranes without the flux-selectivity trade-off problem. Amphiphiles, the core components of the columnar micelles in the HLLC system, play a key role in regulating the nanostructure, their effects on dimensional stability and physicochemical properties of the system however have not been explored well. In this research, we compared the dimensional stability and physicochemical properties of HLLC templates prepared from amphiphiles with various head groups and tail lengths. The amphiphiles with charged head groups (dodecyl trimethylammonium bromide, DTAB, and hexadecyl trimethylammonium bromide, CTAB) enable more monomers to be introduced and a much smaller (∼ 1/2) pore size than that with uncharged ones (polyethylene glycol hexadecyl ether, Brij56). The tail length however mainly regulates the width of water channels with CTAB being 23.27 Å and DTAB about 17.06 Å when the head groups are identical. Although the HLLC systems with CTAB and DTAB present a little bit higher phase transition temperature, the dynamic mechanical stability is much better than that with Brij56 at room temperature, facilitating the reorientation process under an electric force with the order parameter reaching to about 0.9 and the retention of the aligned nanostructure with the absence of the force at room temperature. The study enables a better understanding of the effects of amphiphiles on HLLC templates and their tunability for advanced nanofiltration membranes.

Ultra-stable Pickering liquid crystal-in-water emulsions decorated with thermoresponsive soft microgels and their response to aqueous analytes

This work presents an extensive investigation of the Pickering stabilization of liquid crystal (LC)-in-water emulsions using soft nanometer-sized colloidal poly(N-isopropylacrylamide) (PNIPAM) microgel particles and the responsivity of the PNIPAM microgel-stabilized Pickering LC droplet-based assembly towards amphiphilic analytes. The evolution of size and stability of LC droplets with microgel concentration are found to be dependent on the emulsifier-regime. Despite microgel coating, the LC-water interface remains accessible to model analytes such as anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB). The analytes can pass through the interfacial pores and/or meshes of porous microgels to induce a bipolar-to-radial ordering transition within the droplets. The dose-response behaviour is largely influenced by the initial microgel concentration, type of analytes and interfacial layer (charge), and the number of droplets exposed to the analytes. The PNIPAM microgel-coated LC droplets notably exhibited enhanced sensitivity under conditions promoting electrostatic attractive interactions between the interfacial microgel layer and analytes. Overall, the results highlight the potential of Pickering LC-in-water emulsions for reliable and quantitative analysis of aqueous analytes, thus opening up new avenues toward the development of droplet-based optical sensors.

Synergistic effects of an amphiphilic drug(propranolol hydrochloride) with cationic surfactants in an aqueous medium: A physicochemical study

The interactions of amphiphilic drug(propranolol hydrochloride, PPL) with cationic surfactants, such as dodecyltrimethylammoniumbromide(DTAB), tetradecyltrimethylammonium bromide (TTAB), trimethyltetradecylammonium chloride(TTAC) and tetyltrimethylammonium bromide(CTAB), in an aqueous medium were evaluated. The surface tension measurement was used to examine the mixed micellization behavior and surface properties of drug-surfactant mixtures. The nonideal or synergistic behaviors of the mixed systems were explored by using several physical models, such as Clint, Rubingh, Rosen, and Motomura models, based on regular solution theory and pseudophase approximation. In addition, the synergism between PPL and cationic surfactants was also confirmed using ultraviolet–visible spectroscopy. The stoichiometric ratios, binding constants, and free energy changes of the drug–surfactant mixtures were computed using Benesi–Hildebrand (B–H) theory.