Aqueous Sodium Dodecyl Sulfate Research Articles

Ionic liquid as a cosurfactant for critical heat flux enhancement during boiling with aqueous surfactant solutions

Surfactants are often used to improve boiling heat transfer due to the ease of their implementation. While aqueous surfactant solution significantly increases the heat transfer coefficient (HTC), it is known to deteriorate the critical heat flux (CHF) relative to the base fluid water. The high foamability of most surfactant solutions causes vapor crowding on the heater surface, making surface modification techniques ineffective for CHF enhancement. Here, we address the issue of relative degradation of CHF due to surfactant by using an ionic liquid as a cosurfactant. We employ a unique boiling fluid, where 1-ethyl-3-methylimidazolium chloride ([C2mim][Cl]), a low-foaming ionic liquid, is introduced as a co-surfactant in aqueous sodium dodecyl sulfate (SDS) solution. Motivated by the synergistic increase in foamability of the aqueous surfactant solution due to the addition of ionic liquid, we examine the boiling performance at various combinations of concentrations of the two additives in the solution. The mixture consistently exhibits higher CHF and HTC than an SDS only solution, with the best enhancement observed for a mixture of ≈ 30 ppm SDS and ≈ 750 ppm [C2mim][Cl], resulting in ≈1.6× and ≈1.5× enhancements in CHF and HTC, respectively, compared to the SDS only solution (≈ 30 ppm). We next fine-tune the concentration of cosurfactant to demonstrate an exceptionally high HTC of ≈93 kW/(m2 – ℃) with a CHF value comparable to that of pure water. Enhanced foamability and in-situ improvement in the wettability of the heater surface enhance the HTC and the CHF, respectively. This facile technique for enhancing HTC with water as the base fluid, without compromising on CHF, holds promise for high heat flux thermal management applications.

Enhanced hydrogen sequestration through hydrogen foam generation with SDS Co-Injection in subsurface formations

Inherent obstacles of hydrogen injection encompass preferential channeling through larger pathways, hampering microscopic sweep efficiency within porous media. This work pioneers hydrogen foam generation via co-injection with aqueous sodium dodecyl sulfate (SDS) to enhance subsurface hydrogen trapping capacity. SDS addition substantially reduces hydrogen-water interfacial tension and enhances viscoelasticity. In contrast to robust hydrogen foam stability, CO2 foams display compromised integrity, stemming from surfactant aggregation and ensuing infiltration channels that permit aqueous phase CO2 dissolution. Hydrogen foams conversely sustain uniform surfactant films, forestalling hydrogen ingress into water. Synergetic microfluidic and pore-scale simulations visualise mechanisms underlying intensified hydrogen capture and mobility reduction attributed to deformation and flow resistance when traversing constricted pores. Introducing the amphiphilic SDS surfactant considerably promotes hydrogen adsorption through its hydrophobic tail. Core flooding experiments quantify over 2 times hydrogen storage ratio amplification with SDS relative to sole hydrogen injection. The framework contributes pragmatic strategies to harness high-efficiency hydrogen foam for scalable clean energy storage.

Using Magnetic Micelles Combined with Carbon Fiber Ionization Mass Spectrometry for the Screening of Trace Triazine Herbicides from Aqueous Samples.

Triazine herbicides are commonly used in agriculture to eliminate weeds. However, they can persist in the environment. In this study, we explored a new method for detecting triazine herbicides in aqueous samples. We selected two triazine herbicides, namely, prometryn and ametryn, as model herbicides. To generate magnetic probes, we mixed aqueous Gd3+ with aqueous sodium dodecyl sulfate (SDS), which created magnetic probes made of Gd3+-SDS micelles. These probes showed a trapping capacity for the model herbicides. Results indicated that the trapping capacities of our magnetic probes for ametryn and prometryn were approximately 466 and 468 nmol mg-1, respectively. The dissociation constants of our probes toward ametryn and prometryn were 2.92 × 10-5 and 1.27 × 10-5, respectively. This is the first report that the developed magnetic probes can be used to trap triazine herbicides. For detection, we used carbon fiber ionization mass spectrometry (CFI-MS), which can be used to directly detect semi-volatiles from the samples in the condensed phase. Because of the semi-volatility of triazine herbicides, the herbicides trapped by the magnetic probes can be directly analyzed by CFI-MS without any elution steps. In addition, we also demonstrated the feasibility of using our approach for detecting triazine herbicides in lake water and drinking water.

Sequentially Selective Coalescence of Binary Self-Propelled Droplets upon Collective Motion

Subsequent synthesis and detection using droplets as microreactors have shown promise in the development of novel materials and drugs because microreactors enable small-scale synthesis and detection of covalent/non-covalent intermolecular interactions. Self-organization exhibited by autonomous droplets under non-equilibrium conditions is beneficial for manipulating the sequentiality and selectivity of droplet coalescence because expensive equipment or elaborate techniques are not required with the autonomy of droplets. However, to our knowledge, selective coalescence caused by the collective motion of self-propelled droplets has not been demonstrated in inanimate systems. Here, we report sequentially selective coalescence based on the dynamic collective pattern of self-propelled droplets composed of ethyl salicylate (ES) or butyl salicylate (BS). When ES and BS droplets were placed on an aqueous sodium dodecyl sulfate (SDS) solution, the collective motion of droplets resulted in three stages of selective coalescence on the time development. Initially, coalescence was observed only between different types of self-propelled droplets. Subsequently, the formed droplets selectively coalesced with ES droplets. Finally, mature droplets merged with BS droplets. The sequentially selective coalescence was discussed from the dynamic pattern formation of swarming droplets and the collapse of the SDS monolayer at the o/w interface caused by the difference in Laplace pressure and the interfacial instability at the contact point between droplets. Thus, this study formulates a strategy of sequentially selective coalescence of droplets via the collective motion of non-identical self-propelled droplets, promoting a new type of powerful and efficient automation technology based on an autonomous inanimate manner of spatiotemporal pattern formation under non-equilibrium conditions for the droplet manipulation.

Microflow of nanoemulsion threads in surfactant solutions.

We experimentally investigate the microfluidic flow of oil-in-water nanoemulsions in aqueous sodium dodecyl sulfate (SDS) solutions having different concentrations and injection flow rates. A coaxial microfluidic device is employed to explore the behavior of nanoemulsion threads in these sheathing SDS solutions. Using two high-speed cameras, which simultaneously capture both top and side views, we reveal a variety of flow phenomena, ranging from simple core-annular flow to complex flows, such as gravitational, inertial, and buckling thread flows. By analyzing these complex flows, we develop a methodology that elucidates the relationship of core-annular and gravitational flows at low flow rates. Further, we examine the off-axis displacements and bending of core threads at large flow rates, and we study the buckling dynamics of nanoemulsion threads subjected to osmotic stresses caused by large SDS concentrations in the sheathing fluid.

Non-equilibrium ordering of liquid crystalline (LC) films driven by external gradients in surfactant concentration

HypothesisGradients in the concentration of amphiphiles play an important role in many non-equilibrium processes involving complex fluids. Here we explore if non-equilibrium interfacial behaviors of thermotropic (oily) liquid crystals (LCs) can amplify microscopic gradients in surfactant concentration into macroscopic optical signals. ExperimentsWe use a milli-fluidic system to generate gradients in aqueous sodium dodecyl sulfate (SDS) concentration and optically quantify the dynamic ordering of micrometer-thick nematic LC films that contact the gradients. FindingsWe find that the reordering of the LCs is dominated by interfacial shearing by Marangoni flows, thus providing simple methods for rapid mapping of interfacial velocities from a single optical image and investigating the effects of confinement of surfactant-driven interfacial flows. Additionally, we establish that surface advection and surfactant desorption are the two key processes that regulate the interfacial flows, revealing that the dynamic response of the LC can provide rapid and potentially high throughput approaches to measurement of non-equilibrium interfacial properties of amphiphiles. We also observe flow-induced assemblies of microparticles to form at the LC interface, hinting at new non-equilibrium approaches to microparticle assembly. We conclude that dynamic states adopted by LCs in the presence of surfactant concentration gradients provide new opportunities for engineering complex fluids beyond equilibrium.

Wetting of aqueous sodium dodecyl sulfate droplets on polydimethylsiloxane surfaces during evaporation

Wetting of aqueous sodium dodecyl sulfate (SDS) droplets on polydimethylsiloxane (PDMS) surfaces during evaporation were experimentally studied. After a short-time spontaneous spreading, sessile droplets experienced a period of the constant contact radius (CCR) stage. And it was found that substrate elasticity was found to have an influence on the duration of the CCR stage during the evaporation of aqueous SDS droplets on PDMS surfaces. Moreover, a local contact angle minimum was found during the evaporation of aqueous SDS droplets with an initial SDS concentration below 0.5 CMC. A physical mechanism taking into account the structure of SDS molecules adsorbed at PDMS surfaces was developed for the occurrence of the CCR stage and the local contact angle minimum. Furthermore, two-third power of the instantaneous droplet volume nearly varies linearly with time for all cases.

Use of green-modified micellar liquid chromatography for the determination of Imidocarb dipropionate residues in food samples

Imidocarb dipropionate (IMD) is broadly utilized in veterinary medicine as an antimicrobial to cure many illnesses, particularly anaplasmosis in livestock. Consequently, the rapid determination of IMD residues in edible bovine food samples is of high significance to guarantee food safety. In the meantime, the environmental influences must be considered to reduce the hazardous impacts of control laboratories. Modifying micellar liquid chromatography (MLC) using a natural deep eutectic solvent (NADES), generated utilizing choline chloride (ChCl) and ethylene glycol (EG), was successfully applied to determine imidocarb (IMD) residues in bovine food samples including meat, liver, kidney, and milk. An experimental design approach was employed for multivariate optimization of important mobile phase factors comprising the concentration of sodium dodecyl sulfate (SDS) in mole L-1, and the percentage volumes of NADES, and ethanol (EtOH). The optimal sustainable mobile phase composition was conquered through the Box Behnken design (BBD) optimization approach considering chromatographic peak height, and peak width at 50% of its height (W 50%) as influential responses. The optimal composition of the modified micellar mobile phase was found to be 0.075 M aqueous SDS solution with Ethanol and NADES in the ratio (40:50:10) with pH adjusted to 4.0 using 0.2 M acetic acid solution. At this optimal composition, IMD was efficiently eluted within 0.8 min when the flow rate was 1 mL/min with no interference by endogenous components and proteins in bovine food samples. Pretreatment of food samples was performed by extracting with an aqueous solution of SDS surfactant only. No organic solvent was required during the extraction step. To validate the presented methodology, the regulations of the Food and Drug Administration (FDA) for bioanalytical analysis were applied. The greenness of the proposed method was estimated utilizing three measures involving the Complementary Green Analytical Procedure Index (ComplexGAPI), the Analytical GREEnness metric (AGREE), and the modern White Analytical Chemistry (WAC) assessment tool. Using these tools, a comparative study was conducted between the proposed method and previously reported liquid chromatographic methods. The proposed method was found to be the most sustainable.

Mixed Aqueous Surfactants Solution for Rapid Oil Extraction from Palm Kernel Seed

Adverse effects associated with the use of hexane or other similar organic extraction solvents for extracting oil from oilseeds have been a drive for alternative less toxic oil extracting solvents. This research focuses on oil extraction from grinded palm kernel using solution of mixed aqueous polyoxythylene (23) lauryl ether (BRIJ-35) and sodium dodecyl sulphate (SDS) surfactants and sodium chloride (NaCl) as the electrolyte. Grinded Biomass was agitated in the solution of the mixed surfactant, allowing the extracted oil to be liberated from the seeds as separate phase from the aqueous phase. The effect of SDS concentration, NaCl concentration, contact time and liquid/seed ratio on oil yield was studied. The extracted oil was subjected to Fourier Transform Infrared Spectroscope (FT-IR) characterization to determine the functional groups present in the oil. At optimum conditions for the mixed aqueous surfactant extraction (0.2379 wt.% SDS, 0.5995 wt.% BRIJ-35, 0.3wt.% NaCl, 10 ml/g liquid/solid ratio, 25 min contact time at 25oC), an optimum 78% oil yield was obtained. In contrast, at 50oC for 24hr, an optimum of 81% and 82% oil yield were obtained respectively when hexane and petroleum ether were used as oil extracting solvents. Addition of BRIJ-35 and NaCl to the SDS solution improved the oil yield. Oil extracted using mixed aqueous surfactants, petroleum ether and hexane have the same functional groups indicating the surfactant does not affect the quality of the oil extracted.

Exploring the effects of selected essential amino acids on the self-association of sodium dodecyl sulphate at different temperatures

Sodium dodecyl sulphate (SDS) has well established biological applications in the determination of molecular weights and structure determination of proteins, peptides etc. Due to these reasons, the study of SDS interactions with essential amino acids (AAs) can be valuable as they can diversify the use of SDS in applications of importance in biology and drug delivery designs etc. The aggregation process of SDS and its detailed physiochemical properties in aqueous system, in the presence and absence of three essential amino acids L-Threonine (THR), DL- Methionine (MET) and L-Phenylalanine (PHE), is studied in a temperature range of 293 K-323 K using conductivities, surface tension (γ), particle size and zetapotential measurements using dynamic light scattering (DLS) technique. From conductivity measurements, critical micelle concentration (CMC), counterion binding (β) and thermodynamic parameters such as standard free energy change of micellization (ΔGmo), standard enthalpy change of micellization (ΔHmo), standard entropy change of micellization (ΔSmo) etc., are calculated. The surface properties and interfacial parameters of SDS systems are studied using surface tensiometery. Results established that the presence of amino acids (AAs) reduced the CMC of SDS. The electrostatic interaction of AAs with charged micellar surface were also observed. The micellization process of SDS was found thermodynamically feasible in the aqueous amino acid (AAA) system. From the surface tension data, interfacial parameters such as Гmax, Amin,pC20 , and surface effectiveness of SDS in aqueous and AAA system have been calculated and compared. It was revealed that surface adsorption and rearrangement of SDS molecular ion at their micellar concentration at air/liquid interface are significantly affected by AA addition. Hydrodynamic diameter (Dh) and zetapotential (ζ) of aqueous SDS solution helped to check the effect of amino acid additives on the colloidal size and stability of SDS aggregates. The results from different techniques were consistent to establish the feasibility of SDS micellization process in aqueous as well as aqueous AA solution.

Pyrene interaction with selected heavy metal ions in aqueous sodium dodecyl sulphate (SDS)

Pyrene interaction with Fe3+, Cu2+, Cr3+, Ni2+, Pb2+ was studied in 0.02 mol L-1 SDS. All the studied heavy metal ions quenched the fluorescence intensity of pyrene though variations were found in the level of quenching. Stern-Volmer equation fitted the pyrene quenching by heavy metal ions. Stern-Volmer constants (KSV) were obtained with the fitting of the quenching data with the Stern-Volmer equation. KSV shows the level of quenching and the sensitivity of the method. Greater the KSV larger will be the detection and quantification limit and vice versa. KSV, detection limit (DL) and quantification limit (QL) varied from 9.26 × 103 mol L-1 to 4.13 × 103 mol L-1, 1.61 × 10-6 mol L-1 to 5.85 × 10-6 mol L-1 and 5.38 × 10-6 mol L-1 to 19.49 × 10-6 mol L-1 respectively. The overall sensitivity, DL and QL were observed in the order Fe3+ > Cu2+ > Cr3+ > Ni2+ > Pb2+. Pyrene fluorescence quenching by the studied heavy metal ions is a fruitful method for their determination in environmental samples.

Pool Boiling Heat Transfer Augmentation in a Novel Aqueous Binary Mixture of Surfactants

Abstract This paper investigates the augmentation of heat transfer during pool boiling of a novel aqueous binary mixture of surfactants. The surfactants used were sodium dodecyl sulfate (SDS) (anionic), centrimonium bromide (CTAB) (cationic), and nicotine (nonionic). The aqueous binary mixtures SDS–CTAB, CTAB–nicotine, and SDS–nicotine were prepared on the volume percentage basis. A reduction in surface tension was attained by SDS–CTAB, CTAB–nicotine, and SDS–nicotine aqueous mixtures compared to its individual aqueous surfactant solutions at their optimum concentrations. The most significant surface tension result was obtained by the novel SDS–nicotine aqueous binary system at 25:75 volume percentages. The heat transfer augmentation was investigated by studying the single bubble dynamic in the aqueous SDS–nicotine mixture. The investigation was conducted at two values of heat fluxes to probe the effect of heat flux on bubble dynamics. A significant decrement in the bubble departure diameter and a substantial increment in the release frequency was observed for the SDS–nicotine aqueous mixture at both heat fluxes. The heat transfer coefficient was found to be increased by 36.32% and 58.67% compared to saturated water at low and high heat flux, respectively.

Pyrene Interaction with Selected Amines in Aqueous Sodium Dodecyl Sulphate (SDS).

Pyrene interaction with a group of selected amines such as i.e. benzylamine, phenethylamine, trimethylamine, 1-phenylethylamine was studied in aqueous sodium dodecyl sulfate. All the four amines quenched the fluorescence intensity of pyrene in aqueous SDS. Pyrene acts as a sensitive and selective sensor for the detection of amines in environmental samples. Two different SDS concentrations (0.05mol L- 1 and 0.1mol L- 1) were used to get the optimum SDS concentration for maximum quenching and best detection and quantification limits. Lower SDS concentration (0.05mol L- 1) was found the optimum for maximum quenching, lower detection and quantification limits. Fluorescence quenching of pyrene by the studied amines was treated with the Stern-Volmer equation that resulted in a Stern-Volmer constants (Ksv). Ksv reflects the sensitivity of pyrene for studied amines. Ksv varied between 1.962 × 104 - 0.020 × 103 mol L- 1. A sensitivity, detection limit (DL), quantification limit (QL) of pyrene for studied amines was found in the order Benzylamine > phenethylamie > trimethylamine > 1-phenylethylamine. DL varied from 4.53 × 10- 7 to 4.55 × 10- 4 mol L- 1 and QL varied from 1.51 × 10- 6 to 1.52 × 10- 3 mol L- 1. Method showed excellent reproducibility and is fruitful for the studied amines in environmental samples.

Estuarine sediment toxicity testing with an indigenous subtropical amphipod

This study reports on a sediment toxicity test developed with a native amphipod strain of Ptilohyale barbicornis where sediments from 10 estuarine stations along the western coastline of Taiwan were evaluated with respect to trace metals and PAHs. The test was validated by determining dose–response relationships for aqueous copper, and cadmium and sodium dodecyl sulfate as well as copper-spiked sediment, showing a sensitivity of P. barbicornis indicating its capability serving as a toxicity test species. A significant negative correlation between growth effects after 28 days of exposure to field-collected contaminated sediments and PAHs concentrations was observed. Similarly, the chronic toxicity test showed that growth was mostly inhibited compared to controls, body lengths in particular being significantly different from controls (p < 0.05). Various estuarine sediment pollutants in the quality guidelines can be further evaluated using P. barbicornis to understand their comprehensive biological effects and ecological risks.

Experimental study on pool boiling regime transitions of vertical rod quenched in aqueous surfactant solutions using inverse heat transfer analysis

In this study, the effect of surfactants and liquid temperature on boiling regime transitions of high-temperature rod during quenching was examined using inverse heat transfer analysis. Liquid pools of the aqueous sodium dodecyl sulfate (SDS) and Triton X-100 solutions were used with pure water. In the present experimental range, the critical heat flux (CHF) and minimum film boiling (MFB) point for all test fluids increased as the liquid temperature decreased. On the other hand, the SDS and Triton X-100 surfactants suppressed the CHF and MFB point, which might be due to the enhancement of vapor film stability caused by reduced surface tension. Some previous experimental studies have reported that the surfactants enhance the boiling regime transitions, but their results seem to be contradictory to the present ones. Considering the present study with the previous works, the surfactants seem to have different effect on boiling phenomena depending on the boiling regime. In other words, in the aqueous surfactant solution, the boiling regime transition points seem to be markedly influenced by a path of boiling regime. In addition, boiling mode diagrams were presented for pure water and aqueous surfactant solutions.

Antimicrobial Activity of Microgels with an Immobilized Copper(II) Complex Linked to Cross-Linking and Composition.

The resistance of many bacteria against currently available antimicrobial agents is increasing worldwide at an alarming pace. The described structure-activity relationship study was prompted by the extraordinary ability of water-dispersed microgels to hydrolyze glycosidic bonds similar to building blocks of the peptidoglycan layer of Gram-positive bacteria. The results establish polyacrylate microgels with embedded copper(II) complex as antimicrobial agents. The systematic study reveals that Staphylococcus aureus is susceptible to the microgels, while common commercial agents are found intermediate or resistant. In particular, a microgel with 60 mol % of cross-linking, Cu2LP60%, shows intriguing bactericidal activity at 1 μg/mL, while vancomycin requires a 4-fold higher dose, i.e., 4 μg/mL, for the same effect. The minimum inhibitory concentration of Cu2LP60% was determined as low as 0.64 μg/mL. Excellent stability of the poly(acrylate) microgels was observed by negative zeta potentials in nanopure water and aqueous sodium dodecyl sulfate solution. The composition of the microgel matrix with embedded binuclear metal complex was shown to be responsible for the antimicrobial activity, while the aqueous buffer-surfactant solution is not.

Solubilization of sodium 3‐amino‐2‐hydroxyanthraquinone‐1‐sulphonate in sodium dodecyl sulfate micelles explains its permeation in A549 human lung cancer cell

AbstractSodium 3‐amino‐2‐hydroxyanthraquinone‐1‐sulphonate (AQS) is an analogue of the anthracycline based chemotherapeutic drugs that was prepared as a part of the reported study. As the surfactant micelles mimics the biological membrane the present study comprises the interaction of AQS with an anionic surfactant, sodium dodecyl sulfate (SDS) in aqueous media at pH 7.4 which was monitored by using UV–Visible spectroscopy. The aim of the study is to see whether the present molecule penetrates a biological membrane. Different binding parameters like binding constant, partition coefficient, and corresponding Gibbs free energies of the interaction of AQS and its distribution between aqueous media and SDS micelles were measured. The study revealed that hydrophobic interactions play the most important role in binding of AQS to SDS micelles. To see whether AQS really permeates a biological membrane and induces apoptosis, it was allowed to interact with A549 human lung cancer cells. This study established the fact that AQS results apoptosis by means of nucleation into this cell.

Design of Optimized PEDOT-Based Electrodes for Enhancing Performance of Living Photovoltaics Based on Phototropic Bacteria

Living photovoltaics represent a growing class of microbial devices that are based on whole cell-electrode interactions [1-3]. The limited charge transfer at the cell-electrode interface represents a significant bottleneck in realizing an efficient technology [4]. This study focuses on the development of poly(3,4-ethylenedioxythiophene) (PEDOT)-based electrodes with enhanced charge transfer properties at the interface [5,6]. This is accomplished by the electrosynthesis of PEDOT layers from aqueous sodium dodecyl sulfate (SDS) solutions. Potentiodynamic and potentiostatic electrochemical techniques, as well as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, and theoretical modelling of the electropolymerization transient, were employed to assembly and characterize PEDOT electrodes under various conditions. The produced electrodes are able to capture photosynthetically derived current under multiple light-dark cycles when interfaced with Synechocystis sp. PCC 6803. In the presence of the Synechocystis, the PEDOT electrodes show a six-fold and two-fold enhancement over conventional graphite electrodes for both mediatorless and K3Fe(CN)6 mediated conditions, respectively. The ability of these electrodes to enhance extracted photocurrent for both direct and indirect electron transfer mechanisms provides a versatile platform for improving various microbial devices.[1] Zou, Y., Pisciotta, J., Billmyre, R. B., & Baskakov, I. V. (2009). Photosynthetic microbial fuel cells with positive light response. Biotechnology and Bioengineering, 104(5), 939-946.[2] Pisciotta, J. M., Zou, Y., & Baskakov, I. V. (2010). Light-dependent electrogenic activity of cyanobacteria. PloS one, 5(5), e10821.[3] Schuergers, N., Werlang, C., Ajo-Franklin, C. M., & Boghossian, A. A. (2017). A synthetic biology approach to engineering living photovoltaics. Energy & environmental science, 10(5), 1102-1115.[4] Mouhib, M., Antonucci, A., Reggente, M., Amirjani, A., Gillen, A. J., & Boghossian, A. A. (2019). Enhancing bioelectricity generation in microbial fuel cells and biophotovoltaics using nanomaterials. Nano Research, 1-16.[5] Tamburri, E., Orlanducci, S., Toschi, F., Terranova, M. L., & Passeri, D. (2009). Growth mechanisms, morphology, and electroactivity of PEDOT layers produced by electrochemical routes in aqueous medium. Synthetic metals, 159(5-6), 406-414.[6] Zajdel, T. J., Baruch, M., Méhes, G., Stavrinidou, E., Berggren, M., Maharbiz, M. M., ... & Ajo-Franklin, C. M. (2018). PEDOT: PSS-based multilayer bacterial-composite films for bioelectronics. Scientific reports, 8(1), 15293.

Exploring the effect of hydrophobic ionic liquid on aggregation, micropolarity and microviscosity properties of aqueous SDS solutions

Ionic liquid (IL)-modified surfactant systems have versatile applications in several technological areas. Therefore, it is utmost need to achieve full understanding of interactions existing in such systems before their further uses. Here, the effects of IL, 1-ethyl-3-methylimidazolium hexafluorophospahte, [emim][PF6] on the physicochemical properties of aqueous sodium dodecyl sulfate (SDS) solutions has been studied using multi-technique approach. Various micellar parameters such as critical micelle con-centration (cmc), degree of counter ion dissociation (α), aggregation number (Nagg) as well as some thermodynamic parameters such as standard free energy of micellization (G°m), standard enthalpy of micellization (H°m) and standard entropy of micellization (S°m) and surface properties from surface tension measurement have been evaluated. A significant decrease in cmc, and increase in degree of counter ion dissociation along with increase in Nagg is observed. The aggregation behaviour of SDS is also studied in presence of ILs having different alkyl chain length in their imidazolium cations. A decrease in CMC of SDS observed, and trend of decrease in CMC is reported as [hmim][Cl] > [bmim][PF6] > [emim][PF6]. The micropolarity and microviscosity of micellar media are accessed with fluorescence probe studies. The effect of chain length of IL cation has been also explored on aggregation behaviour. The FTIR technique is employed to evaluate possible interactions between SDS and IL [emim][PF6] molecules, the information regarding size of SDS micelle in presence of IL [emim][PF6] has been explored by DLS technique.

Highly stretchable and thermally healable polyampholyte hydrogels via hydrophobic modification

Aqueous solutions or gels of polyampholytes attract interest for more than half a century due to their several attractive properties. We present here thermally healable hydrophobically modified physical polyampholyte (PA) hydrogels based on oppositely charged 2-acrylamido-2-methylpropane-1-sulfonic acid sodium salt (AMPS) and (3-acrylamidopropyl) trimethylammonium chloride (APTAC) monomers. PA hydrogels were prepared via micellar polymerization technique in the presence of the hydrophobic monomer n-octadecyl acrylate (C18A) in aqueous sodium dodecyl sulfate (SDS) solutions. Charge-balanced PA hydrogels containing 60–90% water exhibit a high tensile strength and stretchability of up to 202 kPa and 1239%, respectively. Above 7 mol% C18A, swollen hydrogels containing around 90% water exhibit much better mechanical properties as compared with the corresponding as-prepared ones because of the stronger hydrophobic interactions in the absence of SDS micelles. Cut-and-heal tests conducted at 50 °C reveal a complete healing efficiency with respect to Young’s modulus for all as-prepared PA hydrogels within 1–4 h.