Dodecyldimethylammonium Bromide Research Articles

Regulating ligand length to improve the PL QY and stability of CsPbCl0.9Br2.1 nanocrystals for LEDs and photoelectric applications

Perovskite luminescent materials have been extensively investigated due to their comprehensive applications for full-color display, lighting, and communication. However, the development of blue-emissive perovskites has seriously lagged behind that of green and red counterparts, primarily because of their low photoluminescence quantum yield (PL QY) and poor stability. Here, we prepared blue-emissive CsPbCl0.9Br2.1 perovskite nanocrystals (PeNCs) and enhanced their QY from 61.3 % to 90.4 % by regulating the chain lengths of ligands. Post-treated PeNCs also exhibit good stability, their PL intensity is maintained at about 90 % after storage at ambient conditions for 10 days. The exciton dynamics results obtained from time-resolved fluorescence spectra and transient absorption spectra show that dodecyldimethylammonium bromide (DDAB), featuring double 12-hydrocarbon chains, is more capable of passivating surface defects and inhibiting non-radiative composites than the other double 8- or double 16-carbon chain ligands, which greatly improved the probability and rate of radiative recombination. Subsequently, the mechanism of ligand chain length regulation on the PL properties and stability of PeNCs was analyzed in terms of ligand-NC surface interaction, ligand polarity, hydrophobicity, and spatial effects. Furthermore, the device based on DDAB-CsPbCl0.9Br2.1 demonstrated stable EL and long operation lifetime, indicating its significant potential as an efficient blue emitter for backlighting in display technologies.

An in-depth exploration of the impact of novel collector HPDDA on the low-temperature flotation behavior of bastnaesite and quantum chemical calculation

Traditional cationic collectors commonly suffer from drawbacks such as poor solubility and low-temperature resistance, which impede the effectiveness of flotation. Hence, this study designed and synthesised a novel collectors, 2-Hydroxypropane-1,3-bis(dodecyl dimethyl ammonium) bromide (HPDDA), tailored for low-temperature flotation of bastnaesite. The positive charges of the surface molecular electrostatic potential (ESP) of HPDDA concentrate near the two quaternary ammonium groups, with minimal points also appearing between the two N atoms. Near the quaternary ammonium groups, weak van der Waals (vdW) and spatial hindrance occur due to the abundance of polar groups. The Krafft point test reveal that the Krafft point of HPDDA was below 0 °C, significantly higher than that of DDA. HPDDA exhibited excellent pH adaptability and cold resistance, demonstrating outstanding selective capturing capability for bastnaesite even at low temperatures, thereby enabling the separation of bastnaesite from calcite. Analysis through various detection methods such as zeta potential, Fourier transform infrared (FT-IR), contact angle measurement, and X-ray photoelectron spectroscopy (XPS) elucidates the selective adsorption mechanism of HPDDA on the surface of bastnaesite, attributing it to the differences in surface electrification and other properties between bastnaesite and calcite. This work provides new collector and theoretical guidance for solving the low-temperature flotation of bastnaesite.

Kinetic and adsorption isotherm studies of Malachite Green dye onto surfactant-tailored alginate hydrogel beads: An influence of surfactant hydrophobicity

This study details the synthesis and characterization of surfactant-modified sodium alginate hydrogel beads crosslinked with Ba2+ ions through ionotropic gelation. Cationic surfactants such as, dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and butanediyl-α,ω-bis-(dimethyldodecylammonium bromide) (GEM), were employed in the modification process. The surfactant-modified ALG-DTAB, ALG-DDAB, and ALG-GEM beads were investigated for the removal of cationic dye Malachite Green (MG) to elucidate the impact of hydrophobicity of amphiphiles on the adsorption process. The characterizations were carried out using Rheometry, Field Emission Scanning Electron Microscopy (FESEM), Infrared Spectroscopy (IR), and Energy Dispersive X-ray Spectroscopy (EDX). Under optimized conditions, ALG-GEM and ALG-DDAB demonstrated highest maximum adsorption capacity (Qmax > 700 mgg−1). The adsorption data fitted well to pseudo-second order kinetic and Langmuir adsorption models, suggesting the involvement of chemisorption phenomena with notable contributions from pore diffusion. The effects of pH, initial dye concentration, adsorbent dose, temperature, and competing ions on the removal of MG were investigated. Interestingly, ALG-GEM beads exhibited an increase in adsorption capacity with rising pH and a subsequent decrease with increasing temperature, showcasing optimal adsorption at pH 7.0 and 25 °C. The study proposes that ALG beads modified with cationic surfactants with higher hydrophobicity could offer a promising avenue in wastewater treatment processes.

Development of Redox-Active Lyotropic Lipid Cubic Phases for Biosensing Platforms.

Enzyme-based electrochemical biosensors play an important role in point-of-care diagnostics for personalized medicine. For such devices, lipid cubic phases (LCP) represent an attractive method to immobilize enzymes onto conductive surfaces with no need for chemical linking. However, research has been held back by the lack of effective strategies to stably co-immobilize enzymes with a redox shuttle that enhances the electrical connection between the enzyme redox center and the electrode. In this study, we show that a monoolein (MO) LCP system doped with an amphiphilic redox mediator (ferrocenylmethyl)dodecyldimethylammonium bromide (Fc12) can be used for enzyme immobilization to generate an effective biosensing platform. Small-angle X-ray scattering (SAXS) showed that MO LCP can incorporate Fc12 while maintaining the Pn3m symmetry morphology. Cyclic voltammograms of Fc12/MO showed quasi-reversible behavior, which implied that Fc12 was able to freely diffuse in the lipid membrane of LCP with a diffusion coefficient of 1.9 ± 0.2 × 10-8 cm2 s-1 at room temperature. Glucose oxidase (GOx) was then chosen as a model enzyme and incorporated into 0.2%Fc12/MO to evaluate the activity of the platform. GOx hosted in 0.2%Fc12/MO followed Michaelis-Menten kinetics toward glucose with a KM and Imax of 8.9 ± 0.5 mM and 1.4 ± 0.2 μA, respectively, and a linearity range of 2-17 mM glucose. Our results therefore demonstrate that GOx immobilized onto 0.2% Fc12/MO is a suitable platform for the electrochemical detection of glucose.

Reversible surface modification of PAN-based carbon fibers by a ferrocene-based surfactant

The surface of carbon fibers (CFs) was modified by a surfactant (ferrocenemethyl)dodecyldimethylammonium bromide (FDDA) to enhance the interfacial ashesion between the CFs and surrounding matrix. Results showed that it could be electrochemically desorbed by a potentiostatic electro-oxidation method. The FDDA adsorption isotherm was attributed to the formation of multi-molecular layers mainly by non-electrostatic interactions. The adsorption and desorption of FDDA on the CFs have little effect on their tensile strength. The effects of FDDA modification on the interfacial properties of CF/epoxy composites were evaluated by a single-filament fragmentation test. Compared with the un-modified CFs, the FDDA-modified ones had significantly improved interfacial adhesion properties in the composites. This method provides a potential approach for preparing recyclable CF/resin composites.

Surface engineered long-lasting antibacterial Janus cotton fabrics with excellent moisture/thermal management properties

The hydrophilic property of traditional cotton fabrics invariably facilitates sweat absorption, potentially leading to discomfort such as cold and clammy sensation, and even promoting bacterial proliferation. Herein, we developed a Janus cotton fabric using a surface engineering strategy combining “graft through” and “mist polymerization” methodologies. Through the “graft through” polymerization of methacryloyloxyethyl dodecyl dimethyl ammonium bromide (DMDB), we constructed a well-designed antibacterial coating on the fabric with amphiphilic properties. The resulting polymer, PDMDB, imparts highly efficient and durable antibacterial properties to the cotton fabric, achieving a bcteriostatic rates against S. aureus and E. coli of > 99.9 %. Even after undergoing 150 washing cycles, the residual bactericidal efficacy remains above 99 %. Additionally, the reversible hydrophilic-hydrophobic nature of PDMDB successfully enables the construction of a Janus structure on cotton fabrics via “mist polymerization”. Benefiting from its comprehensive design, the Janus cotton fabrics realize a superior directional liquid transport property. Its water evaporation rate is 1.3–1.5 times higher than that of the original cotton fabric in continuous outdoor moisture management, while maintaining body temperature 5.63 °C lower than that of the surrounding environment. It is worth mentioning that our approach utilizes abundant raw materials and facile modification technologies, thereby providing a favorable guarantee for the mass production and use of Janus cotton fabrics.

Beneficial or harmful: Time-dependent hormesis induced by typical disinfectants and their mixtures with toxicological interaction

Disinfectants and their mixtures can induce hormesis. However, how the mixture hormesis is related to those of components and the interactions in disinfectant mixtures remain unclear. In this paper, the luminescence inhibition toxicities of chlorinated sodium phosphate (CSP), dodecyl dimethyl benzyl ammonium bromide (DOB), dodecyl dimethyl benzyl ammonium chloride (DOC), ethanol (EtOH), glutaraldehyde (GLA), hydrogen peroxide (H2O2), isopropyl alcohol (IPA), n-propanol (NPA), and 20 mixture rays in four mixture systems (EtOH-H2O2, DOB-H2O2, DOC-EtOH, and EtOH-IPA-NPA) containing at least one component showing hormesis to Vibrio qinghaiensis sp.-Q67 (Q67) were determined at 0.25, 3, 6, 9, and 12 h. The synergism-antagonism heatmap based on independent action model (noted as SAHmapIA) was developed to systematically evaluate the interactions in various mixtures. It was shown that five disinfectants (CSP, EtOH, H2O2, NPA, and IPA) and 17 mixture rays exhibited time-dependent hormesis. The hormetic component was responsible for the hormesis of the mixture rays. Most mixture rays showed low- concentration/dose additive action and high-concentration/dose synergism at different time. This study further exemplified the interrelationship between the hormesis in the mixtures and their components and implied the need to pay attention to the time-dependent hormesis and interactions induced by the disinfectants.

Solvent-free bulk soft material with low-temperature tolerance: Transparency, flexibility, stretchability, and adhesion

Designing and manufacturing reliable and practicable transparent materials that can withstand low-temperature poses significant challenge. In this study, a range of transparent materials with excellent low-temperature resistance were constructed through the synergistic dynamical/non-covalent polymerization of two organic compounds, dodecyl dimethyl benzyl ammonium bromide (DB) and thioctic acid (TA). DB can effectively suppress the crystallization tendency of poly[TA] segments, while TA offers solvent-free polymerization behavior and thermal processing ability. Consequently, the non-covalently linked poly[TA-DB] exhibits high transparency (91.1 ± 3%), strong adhesion (7.91 ± 0.42 MPa), and remarkable stretchability (1705.73 ± 27.05%) in the low-temperature range (−40 ∼ −65 °C) or in cryogenic liquid (−40 °C). The design strategy used in this study offers a supramolecular approach for constructing transparent materials with the low-temperature applicability and practicality.

Effects of environmental disinfection on microbial population and resistance genes: A case study of the microecology within a panda enclosure

Widespread use of disinfectants raises concerns over their involvement in altering microbial communities and promoting antimicrobial resistance. This study explores the influence of disinfection protocols on microbial populations and resistance genes within an isolated enclosure environment and in the gut of giant pandas (GPs) held within. Samples of panda feces, air conditioning ducts, soil and bamboo were collected before and after disinfection. High-throughput sequencing characterized the microbial flora of GP gut and environmental microbes inside the artificial habitat. Microbial cultures showed that Escherichia coli (34.6%), Enterococcus (15.4%) and other pathogenic bacteria deposited in feces and the enclosure. Isolates exhibit a consistent resistance to disinfectant, with the greatest resistance shown to cyanuric acid, and the lowest to glutaraldehyde-dodecyl dimethyl ammonium bromide (GD-DDAB) and dodecyl dimethyl ammonium bromide (DDAB). The total number of the culturable bacteria in soil and bamboo were significantly diminished after disinfection but increased in the gut. After disinfection, the richness (Chao1 index) of environment samples increased significantly (P < 0.05), while the richness in gut decreased significantly (P < 0.05). Ten genera showed significant change in feces after disinfection. Metagenome sequencing showed that 126 types of virulence genes were present in feces before disinfection and 37 in soil. After disinfection, 110 virulence genes localized in feces and 53 in soil. Eleven virulence genes including ECP and T2SS increased in feces. A total of 182 antibiotic resistance genes (ARGs) subtypes, potentially conferring resistance to 20 classes of drugs, were detected in the soils and feces, with most belonging to efflux pump protein pathways. After disinfection, the number of resistance genes increased both in gut and soil, which suggests disinfection protocols increase the number of resistance pathways. Our study shows that the use of disinfectants helps to shape the microbial community of GPs and their habitat, and increases populations of resistant strain bacteria.

Rapid screening of benzyl dodecyl dimethyl ammonium bromide co-metabolic degrading bacteria based on NIR hyperspectral imaging technology

As a typical disinfectant, the use of benzyl dodecyl dimethyl ammonium bromide (BDAB) has dramatically increased since the emergence of SARS-CoV-2, posing a threat to environmental balance and human health. Screening BDAB co-metabolic degrading bacteria is required for efficient microbial degradation. Conventional methods for screening co-metabolic degrading bacteria are laborious and time-consuming, especially when the number of strains is large. This study aimed to develop a novel method for the rapid screening of BDAB co-metabolic degrading bacteria from the cultured solid medium using near-infrared hyperspectral imaging (NIR-HSI) technology. Based on NIR spectra, the concentration of BDAB in the solid medium can be well predicted by partial least squares regression (PLSR) models, non-destructively and rapidly, with Rc2 > 0.872 and Rcv2 > 0.870. The results show that the predicted BDAB concentrations decrease after degrading bacteria utilization, comparing with the regions where no degrading bacteria grew. The proposed method was applied to directly identify the BDAB co-metabolic degrading bacteria cultured on the solid medium, and two kinds of co-metabolic degrading bacteria RQR-1 and BDAB-1 were correctly identified. This method provides a high-efficiency method for screening BDAB co-metabolic degrading bacteria from a large number of bacteria.

In Situ Halide Insertion for Efficient and Stable Pure‐Red Perovskite Light‐Emitting Diodes

AbstractSubstantial efforts have been made in boosting the performance of perovskite light‐emitting diodes (PeLEDs). However, there is still a tough challenge to achieve efficient and stable pure‐red PeLEDs with bromide‐iodine mixed quasi‐two‐dimensional (quasi‐2D) perovskite due to the unexpected halide migration under device operation. Here, the strategy of in‐situ halide insertion is proposed by dynamically treating quasi‐2D perovskite film with dodecyl dimethyl ammonium bromide (DDAB), which simultaneously suppresses the vacancy‐induced halide migration, inhibits the nonradiative recombination, and enlarges the perovskite bandgap for stable and efficient pure‐red emission. Meanwhile, a strong Coulombic force between DDAB and the perovskite is formed, which further anchors the halide for the suppression of halide migration. The merits of DDAB‐incorporated perovskites enable over 3‐fold enhancement in PeLED external quantum efficiency (EQE) from 2.25 to 8.16%. Furthermore, highly‐performed bromide‐iodine mixed pure‐red PeLEDs have been reported with a CIE coordinate of (0.707, 0.289), closely approaching the display standard Rec. 2020 (0.708, 0.292). More importantly, good operational and spectral stabilities without any shift of the electroluminescence (EL) spectra during operation have also been observed. Consequently, this work provides a feasible and effective approach for efficient and stable pure‐red PeLEDs.

Rationalizing the Design of Pluronics-Surfactant Mixed Micelles through Molecular Simulations and Experiments.

Aqueous systems comprising polymers and surfactants are technologically important complex fluids with tunable features dependent on the chemical nature of each constituent, overall composition in mixed systems, and solution conditions. The phase behavior and self-assembly of amphiphilic polymers can be changed drastically in the presence of conventional ionic surfactants and need to be clearly understood. Here, the self-aggregation dynamics of a triblock copolymer (Pluronics L81, EO3PO43EO3) in the presence of three cationic surfactants (with a 12C long alkyl chain but with different structural features), viz., dodecyltrimethylammonium bromide (DTAB), didodecyldimethylammonium bromide (DDAB), and ethanediyl-1,2-bis(dimethyldodecylammonium bromide) (12-2-12), were investigated in an aqueous solution environment. The nanoscale micellar size expressed as hydrodynamic diameter (Dh) of copolymer-surfactant mixed aggregates was evaluated using dynamic light scattering, while the presence of a varied micellar geometry of L81-cationic surfactant mixed micelles were probed using small-angle neutron scattering. The obtained findings were further validated from molecular dynamics (MD) simulations, employing a simple and transferable coarse-grained molecular model based on the MARTINI force field. L81 remained molecularly dissolved up to ∼20 °C but phase separated, forming turbid/translucent dispersion, close to its cloud point (CP) and existed as unstable vesicles. However, it exhibited interesting solution behavior expressed in terms of the blue point (BP) and the double CP in the presence of different surfactants, leading to mixed micellar systems with a triggered morphology transition from unstable vesicles to polymer-rich micelles and cationic surfactant-rich micelles. Such an amendment in the morphology of copolymer nanoaggregates in the presence of cationic surfactants has been well observed from scattering data. This is further rationalized employing the MD approach, which validated the effective interactions between Pluronics-cationic surfactant mixed micelles. Thus, our experimental results integrated with MD yield a deep insight into the nanoscale interactions controlling the micellar aggregation (Pluronics-rich micelles and surfactant-rich micelles) in the investigated mixed system.

Metagenomic insights into the effects of benzyl dodecyl dimethyl ammonium bromide (BDAB) shock on bacteria-driven nitrogen removal in a moving-bed biofilm reactor (MBBR)

The use of disinfectants made from quaternary ammonium compounds (QACs) has greatly increased since the outbreak of SARS-CoV-2. However, the effect of QACs on wastewater treatment performance is still unclear. In this study, a commonly used QAC, i.e., benzyl dodecyl dimethyl ammonium bromide (BDAB), was added to a moving-bed biofilm reactor (MBBR) to investigate BDAB's effect on nutrient removal. When the BDAB concentration was increased to 50 mg L−1, the ammonia removal efficiency (ARE) greatly decreased, as did the nitrate production rate constants (NPR). This inhibition was partly recovered by decreasing the BDAB concentration to 30 mg L−1. Metagenomic sequencing revealed the functional genera present during different stages of the control (Rc) and BDAB-added reactors (Re). The enriched genera (Rudaea, Nitrosospira, Sphingomonas, and Rhodanobacter) in Rc mainly related to the nitrogen metabolism, while the enriched genera in Re was BDAB-concentration dependent. Functional genes analysis suggested that a lack of ammonia oxidase-encoding genes (amoABC) may have caused a decrease in ARE in Re, while the efflux pump-encoding genes emrE, mdfA, and oprM and a gene encoding BAC oxygenase (oxyBAC) were responsible for BDAB resistance. The increase in the total abundance of antibiotic resistance genes (ARGs) in Re revealed a potential risk arising from BDAB. Overall, this study revealed the potential effect and ecological risks of BDAB introduction in WWTPs.

Effect of conventional and Gemini surfactants on the micellar-enhanced ultrafiltration process performance for the separation of Au(III) from aqueous solutions: A dissipative particle dynamics study

Dissipative particle dynamics (DPD) simulation was used to investigate the self-assembled structure of dodecyl trimethyl ammonium bromide (DTAB) and Gemini hexamethylene-1, 6-bis (dodecyl dimethyl ammonium bromide) (12−6−12) surfactants in the aqueous solution. The influence of simulation time and surfactant concentration was studied as the effective parameters on the formation of micelles. The results indicate that by increasing the surfactant concentration, the micellar clusters deform to spherical, wormlike, cylindrical and lamellar shapes, respectively. Subsequently, the effect of surfactant and gold concentrations was investigated for the first time on the performance of the micellar-enhanced ultrafiltration (MEUF) process in the separation of Au(III) from aqueous solutions. The separation efficiency of gold mesomolecules and micellar binding constant was also estimated. The simulation results show the excellent effect of the presence of micelles in the separation of Au(III) using the MEUF process. As the surfactant concentration increases and the micelles grow in size, the probability of bonding between the metal mesomolecules and the micelles also increases and the passage of the gold beads through the polymeric membrane decreases.

Tensiometric and Fluorescence Study of Cationic Gemini Surfactant with Some Special Alcohols

Special alcohols have been used as additives to study interfacial properties of cationic Gemini surfactant pentanediyl- 1, 5-bis (dimethyldodecylammonium bromide) (12-5-12). As these branched chain alcohols (in comparison with linear chain alcohols) are playing a measure roll in creating a microemulsion with Gemini surfactants. The surface tension values were measured by using ring detachment method. During the experiments, the ring was cleaned well by heating it in alcohol flame. The critical micelle concentration (cmc) values were obtained from surface tension (γ) versus logCt plots. The γ values decreased continuously and then become constant along a wide concentration range. The point of break, when the constancy of surface tension begins, was taken as the cmc of the system. Calculated Parameters are cmc, Гmax (maximum surface excess concentration), Amin (minimum surface area per molecule), C20 (the concentration of surfactant where the surface tension of the solvent is being reduced by 20 mN.m-1), (free energy of the given air/water interface), and the standard Gibbs energy of adsorption, ΔG­­0ads. An important property of micelle formation is the mean aggregation number which provides direct information about the general size and shape of the aggregates formed by amphiphiles in solution, and how these properties are related to the molecular structure of the amphiphiles. Mixed micellization behavior has been shown by these parameters. The mean aggregation number (Nagg­) of mixed micelles has been obtained by using the steady state fluorescence quenching method. Some other concerned parameters including dielectric constant (D), binding constant (KSV) were calculated in this study by using the ratio of intensity of peaks.

Water‐resistant organic thermoelectric generator with &gt;10 μW output

AbstractFlexible p–n thermoelectric generator (TEG) technology has rapidly advanced with power enhancement and size reduction. To achieve a stable power supply and highly efficient energy conversion, absolute chemical stability of n‐type materials is essential to ensuring large temperature differences between device terminals and ambient stability. With the aim of improving the long‐term stability of the n‐type operation of carbon nanotubes (CNTs) in air and water, this study uses cationic surfactants, such as octylene‐1,8‐bis(dimethyldodecylammonium bromide) (12–8–12), a gemini surfactant, to stabilize the nanotubes in a coating, which retains the n‐doped state for more than 28 days after exposure to air and water in experiments. TEGs with 10 p–n units of 12–8–12/CNT (n‐type) and sodium dodecylbenzene sulfonate/CNT (p‐type) layers are manufactured, and their water stability is evaluated. The initial maximum output of 16.1 µW (75 K temperature difference) is retained after water immersion for 40 days without using a sealant to prevent TEG module degradation. The excellent stability of these CNT‐based TEGs makes them suitable for underwater applications, such as battery‐free health monitoring and information gathering systems, and facilitates the development of soft electronics.

Evaluation of mixed micellar interactions of CnBCl and SDBS mixtures using dissociated Margules model and influence of different salts

AbstractThe conductivity measurement has been used to determine the first and second CMC's (CMC1 and CMC2) of alkyldimethylbenzylammonium chloride (CnBCl; n = 12, 14 and 16) as well as gemini surfactant trimethylene‐1,2‐bis‐(dodecyldimethylammonium bromide) (12‐2‐12) with sodium dodecylbenzenesulphonate (SDBS) in aqueous solutions using Rubingh's the regular theory approximation as well as the dissociated Margules Model. The use of Margules model allows us to calculate activity coefficients of the constituents and hence provides better values of micellar parameters for asymmetric mixed systems as compared to the regular solution theory. The CMC1 values for CnBCl/SDBS mixtures were seen to be lower than those predicted from their ideal mixtures suggesting synergistic interactions although the synergism increases with chain length (n) of the cationic surfactant. Both CMC1 and CMC2 experience a decrease with rising values of n. The addition of salts including NaCl, KCl, NaBr, Na3PO4, and Na2SO4 in mixtures of C16BCl and SDBS suggests that salt counterions have a considerable impact on CMC1 when either surfactant is in excess. Zeta potential (ζ) measurements provide more evidence in favor of these observations. The thermodynamic features of micellization have also been scrutinized using isothermal titration calorimetry (ITC).

Adsorption behaviors and emission properties of p-sulfonatocalixarene/ammonium-based surfactant systems: A comparison between the effects of gemini surfactant and its corresponding monomeric surfactant

So far, the research on calixarene/surfactant systems has been mainly focused on their aggregation characteristics due to their potential applications as stimuli-responsive systems, while the reports about their absorption behavior and spectroscopic properties have been limited. Understanding basic properties of supra-amphiphilic molecules is of great significance to improve their application performance and expand their application potential. In the present study, the interactions of p-sulfonatocalix[n]arenes (SC[n], n = 4, 6 and 8) with the cationic surfactants (including dodecyltrimethyl ammonium bromide (DTAB), pentamethylene-1,5-bis (dimethyldodecyl ammonium bromide) (12-5-12), and octamethylene-1,8-bis(dimethyldodecyl ammonium bromide (12-8-12)) were studied by measuring surface tension, fluorescence spectra and 1H NMR spectra. It was found that SC[n] changed the absorption behaviors of 12-s-12 (s = 5 and 8) and DTAB at air/water surface in different ways. In the presence of SC[n], the value of γ for 12-s-12 remains almost constant until 12-s-12 content reaches C1, then decreases sharply until C2, followed by a slow decrease up to the CMC. The surface tension of DTAB/SC[n] solution begins to decrease at a very low concentration of DTAB until Ca, followed by a short plateau until Cb, and then, the surface tension increases sharply until Cc, after which, the surface tension curve gradually overlaps with that of single DTAB solution. Meanwhile, the binding of SC[n] with these surfactants makes SC[n] emit fluorescence, and the quantum yields for SC[n]/12-s-12 systems are higher than those for SC[n]/DTAB systems. Supra-amphiphiles have been expected as smart materials. This study may provide meaningful information for application of calixarene-based supra-amphiphiles.

Significance of dimeric surfactant on kinetic study of organophosphorus compounds

AbstractDimeric surfactants have shown significant role on hydrolysis of organo‐phosphorus compounds. In this study, we have studied the kinetic hydrolysis of p‐nitrophenyl acetate (PNPA), p‐nitrophenyl benzoate (PNPB), and p‐dinitrophenyl diphenyl phosphate (PNPDPP) in presence of novel dimeric surfactants 12‐4‐12, 2Br– (butanediyl‐1,4‐bis(dimethyldodecylammonium bromide), 12–4(OH)‐12, 2Br– (2‐butanol‐1,4‐bis(dimethyldodecylammonium bromide) with conventional nucleophiles, benzohydroxamic acid (BHA), and salicylhydroxamic acid (SHA) by spectrophotometry at 27°C. Kinetic study on effect of micelles on reaction rates have been investigated and rationalization effects of micelles determination using kinetic model. The experimental kinetic data were fitted with micellar pseudophase model for determination micellar substrate binding and parameters. The second order rate constant is processed for comparing the reactivities in aqueous and micellar pseudophase.

Synergistic corrosion inhibition effects of quaternary ammonium salt cationic surfactants and thiourea on Q235 steel in sulfuric acid: Experimental and theoretical research

The corrosion resistance of Q235 steel treated with pure thiourea, dodecyl trimethyl ammonium bromide (DTAB), dodecyl dimethyl benzyl ammonium bromide (DDBAB), and their mixture (i.e. DTAB-Thiourea, DDBAB-Thiourea) in sulfuric acid was studied. Results showed that DTAB-Thiourea and DDBAB-Thiourea have strong synergistic effects (4.86 and 5.99) and could inhibit corrosion by 93.37% and 94.98%, respectively. These effects are attributed to a decrease in the steric hindrance due to changes in the molecular adsorption mode of the corrosion inhibitors. The adsorption forms of all inhibitors on the steel surface were investigated and explained using density functional theory.