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Reverse micelle (RM) aggregates have a wide range of applications in various areas of science and technology. A continuous demand exists to replace interfacial surfactant molecules with various nonconventional amphiphiles. Ionic liquid (IL)-like surfactants (IL-surf's) constitute a class of such molecules that are being researched extensively. Here, we have formulated several water/IL-surf/oil microemulsions by optimizing the core droplet size with varying oil phases. The best composition of water/[BMIM][AOT]/IPM ([BMIM][AOT]: 1-butyl-3-methylimidazolium dioctyl sulfosuccinate; IPM: isopropyl myristate) was then analyzed in detail through experimental and computer simulations. Our results from DLS measurements suggest a structural transition from spherical aggregates in the parent water/[Na][AOT]/IPM solution to cylindrical droplets in the IL-surf-based system. The Raman and ATR-FTIR spectral analysis suggest a variation in the microstructure of the water/oil interface due to the differential interaction of the counterions with AOT headgroups and water. Molecular dynamics simulation results provided the direct image of the interface showing a structured versus uneven water/oil interface in [Na][AOT] versus [BMIM][AOT] RMs, where the larger [BMIM] cations weakly bind with the AOT headgroups due to their low charge density. Finally, an application of this IL-surf-based formulation was tested by carrying out a Heck cross-coupling reaction that showed significantly higher yield under milder reaction conditions.

Tea is not only the most popular beverage in the world but also producing a large quantity untreated wastes product every year. In particular, the tea gardens of eastern Sub-Himalayan region cumulatively produce 15 million kg of crush, tear, curl (CTC)-factory tea waste (FTW) every year, which primarily includes discarded tea leaves, leaf fibers, buds and tender stems of tea plants. Beside that ~ 80% population of Indian subcontinent consume CTC tea regularly at their homes, tea stalls, market, cafe etc. and the waste produced from it, is called CTC domestic tea waste (DTW). Thus, not only factory tea waste but also a large quantity of domestic CTC tea waste (DTW) is exposed into the environment regularly. In present study, an attempt has been made for primary screening of the compounds in both the CTC-tea wastes. It has been shown that FTW sample contains greater amount of non-metal elements such as sulfur, calcium, phosphorus and metal elements like potassium and iron compared to DTW sample. Abundance of aromatic compounds has been seen to be higher in FTWs whereas, DTW primarily contains aliphatic compounds. Using Orbitrap-HRLCMS analysis allowed to make accurate predictions about the molecular structures of the likely organic chemicals found in tea trash. Thus, various bioactive organic compounds, micronutrients and trace elements from tea waste were found.

The interfacial properties of the mixed amphiphiles are modified by a stronger cation-π interaction between the quaternary ammonium head group of CTAB and the π-face of TROE, compared to the tyrosine analogue (TYOE). This eventually triggers a morphology transition through elastic deformation of the spherical micelles of CTAB to cylindrical/wormlike micelles. The unfolding of TROE and the molecular interactions in the nanoenvironment have been recognized by NMR spectroscopy and the physical characteristics of the entangled wormlike micelles are investigated by high resolution transmission electron microscopy (HRTEM), whereas the complex fluidic feature is examined by dynamic rheological measurements. Morphology tuning of the soft nanoaggregates of zwitterionic dodecylphosphocholine by the tryptophan analogue via choline-π interaction has unique biological consequences and we consider the significance of such interactions in facilitating endocytosis of a virion/nano particle(NP) in terms of a quantitative model. The implication in future research on drug development strategies is discussed.

Discrete water domains in hydrophobic environment find relevance in aerosols, oil refinery, the human body, etc. The interfacial microstructure plays a crucial role in the stability of such water domains. Over the decades, the amphiphile-induced electrostatic interaction is considered to be the major stabilizing factor operating at these interfaces. Here we take the representative water/AOT/oil microemulsion to show that creating a strong H-bonding network through suitable additive, such as protic ionic liquid (IL) at the interface, helps both the growth and stability of water domains in the hydrophobic phase. On the other hand, common electrolytes and aprotic ILs fail to replicate such behavior as seen by Raman, Fourier transform infrared spectroscopy, dynamic light scattering (DLS), and electron microscopy measurements. Experimental results are further supported by the all-atomic molecular dynamics (MD) simulations that showed extended H-bonding mediated by the protic IL cations that were localized at the interface. High temperature DLS and rheology studies have shown greater thermal stability and mechanical strengths of our biocompatible microemulsions, which have potential to become suitable templates for in situ synthesis of nanoparticle and various organic compounds.

The interfacial properties of the mixed amphiphiles are modified by a stronger cation-π interaction between the quaternary ammonium head group of CTAB and the π-face of TROE, compared to the tyrosine analogue (TYOE). This eventually triggers a morphology transition through elastic deformation of the spherical micelles of CTAB to cylindrical/wormlike micelles. The unfolding of TROE and the molecular interactions in the nanoenvironment have been recognized by NMR spectroscopy and the physical characteristics of the entangled wormlike micelles are investigated by high resolution transmission electron microscopy (HRTEM), whereas the complex fluidic feature is examined by dynamic rheological measurements. Morphology tuning of the soft nanoaggregates of zwitterionic dodecylphosphocholine by the tryptophan analogue via choline-π interaction has unique biological consequences and we consider the significance of such interactions in facilitating endocytosis of a virion/nano particle(NP) in terms of a quantitative model. The implication in future research on drug development strategies is discussed.

Owing to the fascinating applications of ionic liquids (ILs) based non-aqueous microemulsions (MEs) in the field of chemical reactions due to their high thermal stability compared to that of aqueous MEs and requirement of water-free environment, we designed a high-temperature stable cationic IL-in-oil microemulsions using 1-ethyl-3-propylbenzimidazolium bromide ([EPbim][Br]) as a polar phase for the first time. In order to determine the thermodynamic stability of such type of MEs, we measured the distribution of cosurfactant (herein, 1-octanol) between bulk n-decane phase and interface covered by quaternary ammonium head group of cetyltrimethylammonium bromide (CTAB) at elevated temperature. The spontaneous formulation of high-temperature IL-in-oil MEs with organized IL-oil interface was identified by the negative free energy and entropy change at studied temperature range (358–370 K). Interestingly, we observed temperature-independent exothermic behavior at a specific composition, which probably comes from the cation-π interaction between quaternary ammonium head group of CTAB and aromatic moiety of ILs. We performed phase behavior study to demonstrate a wide range of thermally stable of [EPbim][Br]/CTAB/decane MEs. Surprisingly, the droplet size was decreased with progressive addition of IL, which may be due to the difficulty of formation of strong and favourable H-bond between the polar head groups of CTAB and [EPbim][Br] at higher temperature. Furthermore, the aggregation number and molecular interfacial area at higher temperature were calculated, which have direct correlation with the droplet size. Finally, the nitration reaction with three different aromatic compounds was performed in this MEs media at the temperature-independent composition. The reaction was completed with the highest regioselectivity of para isomer product over the ortho one. Moreover, these results clearly highlight an efficient way towards the formulation of high temperature stable MEs with ILs at ambient pressure and open a wide field of potential applications.

Extensive investigation on self-assembly of DDAB in aqueous medium is severely restricted due to its insolubility. However, DDAB is highly soluble in acetonitrile, which allows investigation in a wide range of concentrations. An unusual aggregation phenomenon is exhibited by DDAB in acetonitrile, displaying six breaks in conductivity-concentration profile in a wide concentration regime. This study along with that of steady state fluorescence measurements indicate the presence of six-step self-assembly phenomena to occur in the system. HRTEM experiments show the presence of fascinating morphologies of the aggregates. The experimental observations are analyzed and the driving forces behind the phenomena are discussed.

Two new compounds namely, 6-methyl-1-(p-tolyl)hept‑3‑yne-1,5-diol (1) and N-(5‑hydroxy-1-phenylhex-3-yn-1-yl)-4-nitrobenzenesulfonamide (2) have been synthesized and structurally characterized through single-crystal X-ray diffraction analysis. X-ray crystallography reveals that the structures are stabilized through hydrogen bonds. However, compound (1) exhibits dual C–H∙∙∙π interactions. The solid-state supramolecular self-assemblies have been reconnoitered in detail for both structures. The noncovalent interactions that are exhibited by the structures are quantified through Hirshfeld surface analyses. The noncovalent interactions are characterized by Bader's theory of ‘atoms-in-molecules’ (AIM). Additionally, the supramolecular frameworks are further characterized by the theoretical ‘Noncovalent Interaction’ (NCI) plot index.

The present report was undertaken due to the scarcity of information regarding the microstructural transition from aqueous to acetonitrile (ACN)-based non-aqueous reverse micelles (RMs) stabilized by cationic didodecyldimethylammonium bromide (DDAB) and anionic sodium bis(2-ethylhexyl) sulfosuccinate (AOT) in cyclohexane. The synergistic solubilization capacity of corresponding polar solvent at a fixed composition and the nature of conductance plots in these RMs were markedly varied along with the composition of binary solvents (water and ACN at pure or mixed states) and the surfactant charge types (DDAB and AOT). The structural alteration in these RMs through water- and ACN-rich compositions were studied by FTIR, where the results were explained in terms of molecular states of water and ACN inside RMs. The differential binding affinity of both polar solvents with the two surfactants was shown using ab initio calculations. The subsequent appearance and disappearance of aqueous nano-pool was verified from UV-Vis technique using CoCl2. The lack of H-bonding ability on going from aqueous to ACN-based RMs was evidenced from the temperature-dependent DLS study along with the absorption profiles of 7-hydroxycoumarin. The results showed how the microstructures and H-bonding interactions inside RMs are dramatically altered by simply changing polarity of the solvents or the surfactant charge-types. This report could be useful to understand the formation mechanism of two class of RMs.

The nature of transition from ordinary micelles (of nanometer length scale) of surface active ionic liquid 1-Hexadecyl-3- methylimidazolium chloride, to wormlike micelles (WLM) (micrometer length scale), mediated by hydroxy aromatic π-electron systems 1-Naphthol, 2-Naphthol and 2,3-Dihydroxynaphthalene (2,3-DHN) in salt free condition have been studied under Newtonian as well as non-Newtonian flow regimes. Conductance and tensiometry show that the additives lower the CMC of the ionic liquid. The interaction parameter (β) of the systems at different mole fraction evaluated on basis of Rubingh's Regular solution approach were negative at all SAIL/Additive compositions. UV–vis spectroscopy showed that micelle-bound additives formed hydrogen bonds with interfacial water molecules. Increase in steady state fluorescence anisotropic measurements revealed that the additives increasingly partitioned within the micelles. 1 H NMR study confirmed that although the additives reside at the palisade layer, they perturb the micellar core as well. At higher concentration (100 mM, 1:1), systems formed transparent viscoelastic gel. Rheological study of the viscoelastic gels showed that their zero shear viscosity is a function of temperature. 2,3-DHN interacted most strongly with the SAIL micelles, both in Newtonian and non-Newtonian regimes. This was corroborated by DFT study of binding energy. Hydrogen bonding of the hydroxy functionality along with strong cation-π interaction between the aromatic moieties and the imidazolium ring are considered as the main driving forces behind the morphology change. The viscosity of C 16 -3-MeImCl/1-Naphthol increased as function of salt concentration unlike C 16 -3-MeImCl/NaSal system. A possible mechanism is suggested and discussed. The present study sheds light on understanding the molecular interactions behind the structural change from spherical to elongated micelles, in both microscopic and macroscopic scale, triggered by hydroxy naphthalenes under salt-free condition. The metal tolerance of the gels has huge application prospects as fractured fluids in oil-mining industry.

Using the benefits of superior surface activity of surfactant-like ionic liquids (SAILs) and synergistic interaction of oppositely charged surfactants, herein we formulate the oil/water interface composed of equimolar composition of 1-hexadecyl-3-methy-limidazolium chloride (C(16)mimCl) and polyoxyethylene (20) cetyl ether (Brij-58) for the first time. The primary role of cosurfactant to stabilize the interface of water-in-oil droplets was investigated by using isomeric cosurfactant (e.g., 1-pentanol and isoamyl alcohol). The distribution of cosurfactant in interfacial region of nano droplets and bulk oil was evaluated as a function of different hydration level, and temperature. Energetic studies revealed formation of the organized oil/water interface by releasing heat during transfer of cosurfactant from oil to interface. Droplet morphology was examined to visualize the effect of water content, and added Brij-58. Mechanistic information of percolation behaviour was discussed with help of DLS results. Various hydrogen bonding environment of entrapped water along with partitioning behaviour was established from novel fluorescence deconvolution method and correlated with FTIR and time-resolved fluorescence studies. The antimicrobial activity of microemulsions along with individual components was measured against Gram-negative and Gram-positive bacteria. Mixed C(16)mimCl/Brij-58 micro-emulsion confirmed as efficient antimicrobial agent compared to the individual components.

Mixtures of dissimilar surfactants can have superior properties compared to those of the individual surfactant components involved, which provide impetus for research on interactions between surfactants. It was also demonstrated that a change in the composition of external phase promotes remarkable changes in interfacial properties of reverse micelles (RMs), which are crucial to understand the system in order to use them as nanoreactors. Hence, it should be achievable to explore the influence of non-ionic Tween-85 on the properties of anionic AOT based micelle as well as RMs in fatty acid esters [e.g., ethyl myristate (EM), ethyl palmitate (EP) and ethyl oleate (EO)]. A comprehensive micellization behavior is studied at different mixed compositions (XTween-85) by surface tension method. Non-ideal mixing behaviors along with synergistic interaction between the constituent surfactants in the mixed micelles are evidenced. Mixed micelles illustrate favorable micellization behavior in terms of thermodynamic parameters. Further, fatty acid ester medium-based mixed RM shows synergism in water solubilization capacity. Microstructures of these systems are investigated by conductance, DLS, and FTIR studies. The solvation and rotational relaxation dynamics using picosecond time-resolved emission spectroscopy (TRES) is used to investigate the effect of XTween-85 as well as chemical architecture of fatty acid esters for the first time on the excited state dynamics of fluorophore. The solvation dynamics is found to be faster with an increase in XTween-85 and the average solvation time follows the order, EO

Smart wormlike micellar blends can be readily formed from surfactant micelles in presence of counterion, salt or under varying conditions of pH, concentration, salinity driven by cation-π interaction whereas the role of π-π interaction in the same remains less explored. In this investigation the impact of π-π interaction on nanoaggregates of cationic amphiphile viz., cetylpyridinium bromide (CPB) in contrast with the cation-π interaction in cetyltrimethylammonium bromide (CTAB) in the presence of surface-active aromatic π conjugated hydroxy aromatic derivatives of naphthalene viz., 1 Naphthol, 2 Naphthol and 2,3 Dihydroxynaphthalene is reported. The presence of π-π interaction in CPB enables stronger synergism between the hydroxynaphthalenes compared to the non-aromatic analogue CTAB while face-to-face stacking interaction in CPB-hydroxynaphthalene systems lead to formation of worm like micelle (WLM) with relatively short entanglement lengths as compared to that in CTAB. The modification of surface parameters and molecular interactions of the systems are studied via tensiometry, 1H nuclear magnetic resonance (NMR), 2D-Nuclear Overhauser effect spectroscopy (NOESY) and small angle neutron study (SANS). The non-Newtonian behavior of the complex fluids comprising the cationic amphiphiles and hydroxyaromatic derivatives are studied using static and dynamic rheometry.

Hypothesis Although several studies on water-in-hydrocarbon oil microemulsions stabilized by anionic surfactant are available in literature, such study on oils possess comparable molar volumes with different chemical architectures and physicochemical properties, herein R -(+)-limonene (LIM) and isobutyl benzene (IBB) derived microemulsions in absence or presence of ionic liquid (IL) warrants uniqueness of this report. Experiments The present study delineates interfacial composition and thermodynamics properties of sodium dodecylsulfate, SDS/1-pentanol/LIM or IBB/water microemulsions in absence or presence of IL, 1-butyl-3-methylimidazolium chloride (bmimCl) as additive by the dilution method. Further, precise characterization of these systems is accomplished by conductivity and DLS studies as function of ω , [bmimCl] and temperature, which provide an insight into unique features of the oil/water interface. Finally, the influence of distinctive features of oils and the states of water organization in nanopool of these microemulsions have been explored from steady state fluorescence emission, fluorescence anisotropy and FTIR measurements. Findings bmimCl containing microemulsions are more spontaneous than aqueous microemulsions. Addition of bmimCl yields smaller droplets compared to aqueous system. Fluorescence measurements reveal penetration of oil molecules in the surfactant palisade layer vis-a-vis interfacial micropolarity and their consequential effects in microenvironment of microemulsions in absence or presence of bmimCl, using suitable molecular probes. Apart from reciprocal variation in free and bound water with increasing water content, results exhibit mild variation in interfacial water (which is basically trapped water in the hydrophobic tail region of surfactant) by changing oil continuum. Finally, correlation of the results in terms of evaluated physicochemical and thermodynamic parameters has been presented.

In this report, phase behavior, conductivity, viscosity, dynamic light scattering, fluorescence lifetime, steady state fluorescence anisotropy and Fourier transform infrared spectroscopy (FTIR) techniques were employed for understanding of the physicochemical properties and microenvironment of water-in-oil microemulsion comprising equimolar (1:1) cetyltrimethylammonium bromide (C16TAB) and polyoxyethylene (20) cetyl ether (C16E20)/1-butanol/heptane or decane, with varying water content (ω) at 303 K. Both conductivity and viscosity of these systems were increased with increase in ω in both oils. Droplet size was also increased with increase in ω and corroborated well with the conductance and viscosity measurements, and depends on oil chain length. The physicochemical changes in the microenvironment with increase in ω were presented by measuring the changes in decay time using a fluoroprobe (7-hydroxycoumarin). The effect of hydration on the microstructure of these systems was studied by polarized fluorescence measurements. FTIR measurements reveal three states of water molecules, viz. trapped, bound and bulk water, in water pool of these systems. Further, the interfacial composition and free energy of transfer of 1-butanol from oil to the interface were evaluated by the dilution method. Changes in interfacial composition as a function of ω corroborate well with FTIR results indicating bound and bulk water.

A simple, competent, green pathway has been developed for the Pd catalyzed ligand free homocoupling reaction of arylboronic acids in water under ambient conditions. An efficient reaction environment is generated using a combination of Pd(OAc)2 and ‘green additives’, which exhibited excellent activity and results in high yields of the desired coupled products within 15 minutes.

In this contribution, phase behavior and the Schulman's cosurfactant titration of a quaternary water-in-oil microemulsion, formed from equimolar cationic [alkyltrimethylammonium bromide (CnTAB)] and nonionic [polyoxyethylene (20) cetyl ether (C16E20)] surfactants, n-pentanol (Pn) and n-heptane or isopropyl myristate, have been studied along with the variation in alkyl chain length of the cationic surfactant, Cn (n = 12, 14, 16 and 18) at a fixed water content (ω = 25) and temperature (303 K). The synergies in single-phase microemulsion zone, interfacial composition and the spontaneity of formation of mixed surfactant microemulsions have been observed with increase in Cn (n = 12 → 18). Further, the effect of the variation of Cn (n = 12 → 18) on the interface vis-a-vis interdroplet interaction, morphology and the dynamics of confined water of these systems have been examined by means of viscosity, dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR) measurements. The increase in the Cn (n = 12 → 18) leads to shrink the droplet size as well as increase in the droplet numbers. Subsequently, the change in droplet size affects the states of water organization (bulk and bound) inside the pool. Additionally, the influence of different inorganic salts [normal salt (NaCl), precursor salt for nanoparticle synthesis (NiCl2, FeCl3), water structure affective salt (KF, KI)] on the transfer process of Pn (oil → interface) at equimolar composition (of both surfactants) has been investigated. FTIR measurement (via D2O probing) indicates that the presence of salts significantly modifies the water structure in confined environment.

The present study is focused on evaluation of interfacial compositions and thermodynamic properties of w/o mixed surfactant [(sodium dodecylsulfate, SDS/polyoxyethylene (23) lauryl ether, Brij-35)/1-pentanol (Pn)/isopropyl myristate (IPM)] microemulsions under various physicochemical conditions by the dilution method. The number of moles of Pn at the interface (n(a)(i)) and bulk oil (n(a)(o)), and various thermodynamic parameters [viz. standard Gibbs free energy (ΔG(o→i)(0)), standard enthalpy (ΔH(o→i)(0)), and standard entropy (ΔS(o→i)(0)) of the transfer of Pn from bulk oil to the interface] have been found to be dependent on the molar ratio of water to surfactant (ω), concentration of Brij-35 (X(Brij-35)), and temperature. Temperature-insensitive microemulsions with zero specific heat capacity (ΔC(p)(0))(o→i) have been formed at specific compositions. The intrinsic enthalpy change of the transfer process (ΔH(0))(o→i)* has been evaluated from linear correlation between ΔH(o→i)(0) and ΔS(o→i)(0) at different experimental temperatures. The present report also aims at a precise characterization on the basis of molecular interactions between the constituents and provides insight into the nature of the oil/water interfaces of these systems by conductivity and dynamic light scattering studies as a function of ω and X(Brij-35). Conductivity studies reveal that incorporation of Brij-35 in non-percolating water/SDS/Pn/IPM systems makes them favorable for ω-induced percolation behavior up to X(Brij-35) ≤ 0.5. But further addition of Brij-35 causes a decrease in conductivity with increasing ω. Furthermore, the hydrodynamic diameters of the microemulsion droplets increase with increase in both X(Brij-35) and ω. Correlations of the results in terms of the evaluated physicochemical parameters have been attempted.

Objectives: The purpose of the present study is to focus on the types of wastages that generated as a byproduct from tea processing industries. Quality and quantities of tea waste and their proper management or waste disposal method were determined in Terai and Duars region of West Bengal. There are very few companies or societies who buy a very little amount of tea waste that does not have any significant impact on the tea waste management as a whole. Lastly, there is a lack of comprehensive and uniform guidelines towards tea waste management in this area. Methods: Random cluster sampling technique in selecting 20 study sites, out of the 30 tea factories that are spread in four major tea producing districts namely foothills of Darjeeling, Jalpaiguri, Alipurduar and a part of Cooch Behar were performed. Primary and secondary data are documented during data collection, using questionnaires, interviews, observation and necessary photographs were taken. Findings: Authors have attempted to bring out this work to develop some management strategy of tea waste. Our survey report indicated that effective management strategies would improvise socio-economic status of tea garden workers as well as owners by utilizing this waste in poultry and fish feed, garden manure and caffeine extraction. Applications/Improvement: Fibers from tea waste can now be converted into different industrially implemented products like low cost absorbent during removal of pollutants from waste water. New technologies are emerged through which factory tea waste might be utilized for the preparation of n-triacontanol, which is commercially valuable bio-nutrient and has important growth promoting activities of leaf primordia.

The intrinsic viscosity [η] of sodium alginate having different molecular weights (high molecular weight (type A), medium molecular weight (type B) and low molecular weight (type C)) is measured at 293–303 K temperature in various mixtures of water (good solvent), acetone (ACE, poor solvent) and water-ethoxy ethanol (EE, poor solvent). The observed result particularly the Huggins constant (K H) values shows a significant variation of cosolvency as a function of solvent composition (ΦACE/ΦEE) and the temperature. Unperturbed dimensions (K θ) under non-theta condition have been calculated using various equations in different water-acetone and water-ethoxy ethanol mixtures. The value of K θ obtained from three different methods of measurements viz., Burchard-Stockmayer and Fixman (BSF), Berry and Inagaki-Suzuki-Kurata (ISK) agree well with each other except in a few compositions of solvents. The molecular extension factor (α n) and actual end-to-end distance (α n K θ) have also been computed herein. Further, the shear thinning nature of the sodium alginate solutions (representative illustration: type A) in water and water-acetone mixed systems has been investigated at increasing strain rate. Results show that the viscous modulus G″ predominates over the elastic modulus G′ and the systems behave as viscoelastic fluids under present conditions. Higher value of G′ in acetone-water mixed solvent system compared to that in pure water undoubtedly indicates enhancement of the elasticity in alginate system in the presence of acetone. Finally, zeta potential measurement demonstrates that the polymeric surface of sodium alginate (representative illustration: type A) is essentially negatively charged and the zeta potential of the polymer is more responsive to the composition of ethoxy ethanol than that of acetone in the aqueous-organic mixed solvents.

The critical micellization concentration (CMC) of ammoniumdodecyl sulfate (ADS) in different tetraalkylammonium bromides (TAAB) viz., tetramethylammonium bromide (TMAB), tetraethylammonium bromide (TEAB), tetrapropylammonium bromide (TPAB), and tetrabutylammonium bromide (TBAB), in the concentration range of 0.0005 to 0.005 M were measured by electrical conductivity method. Micelle formation of ADS in these electrolyte media favours CMC reduction in the order TBAB > TPAB > TEAB > TMAB. The thermodynamic parameters of micellization, , , and , were evaluated in 0.001 M of different TAAB solutions in the temperature range of 288.15 to 318.15 K. Large positive values suggest the overall micellization to be entropy driven. and compensate each other with compensation temperature of 304 ± 2 K. ADS solution manifests clouding in presence of TBAB. With fixed [ADS] and varying [TBAB], CP decreases steeply at the initial [TBAB], but changes little above [TBAB]/[ADS] mole ratio of 1:1. The results have been explained...

The intrinsic viscosities [η] of poly(vinyl alcohol)s (PVAs, which are biocompatible polymers)—with different (high, medium, and low) molecular weights were measured at 293–303 K in water (good solvent)–acetone (ACE, poor solvent) and water–tetrahydrofuran (THF, poor solvent) mixtures. The results observed, particularly the values of the Huggins constant (K H), indicated that the solvency of each PVA varied as a function of solvent composition (Φ ACE/Φ THF) and temperature. The unperturbed dimensions (K θ) of the PVAs under nontheta conditions in a variety of water–acetone and water–tetrahydrofuran solutions were also calculated using various equations. The values of K θ obtained via three different equations, i.e., those of Burchard–Stockmayer–Fixman (BSF), Berry, and Inagaki–Suzuki–Kurata (ISK), agreed well except for a few solvent compositions. The molecular extension factor (α n) and actual end-to-end distance (α n K θ) of each PVA were also computed.

A simple, competent, green pathway has been developed for the Pd catalyzed ligand free homocoupling reaction of arylboronic acids in water under ambient conditions. An efficient reaction environment is generated using a combination of Pd(OAc)2 and ‘green additives’, which exhibited excellent activity and results in high yields of the desired coupled products within 15 minutes.

Hypothesis Modification of the interface by blending of surfactants produces considerable changes in the elastic rigidity of the interface, which in turn affects the physicochemical properties of w/o microemulsions. Hence, it could be possible to tune the thermodynamic properties, microstructures and antimicrobial activity of microemulsions by using ionic/non-ionic mixed surfactants and polar lipophilic oil, which are widely used in biologically relevant systems. Experiments The present report was aimed at precise characterization of mixed cetyltrimethylammonium bromide and polyoxyethylene (23) lauryl ether microemulsions stabilized in 1-pentanol (Pn) and isopropyl myristate at different physicochemical conditions by employing phase studies, the dilution method, conductivity, DLS, FTIR (with HOD probing) and 1H NMR measurements. Further, microbiological activities at different compositions were examined against two bacterial strains Bacillus subtilis and Escherichia coli at 303 K. Findings The formation of mixed surfactant microemulsions was found to be spontaneous at all compositions, whereas it was endothermic at equimolar composition. FTIR and 1H NMR measurements showed the existence of bulk-like, bound and trapped water molecules in confined environments. Interestingly, composition dependence of both highest and lowest inhibitory effects was observed against the bacterial strains, whereas similar features in spontaneity of microemulsion formation were also evidenced. These results suggested a close relationship between thermodynamic stability and antimicrobial activities. Such studies on polar lipophilic oil derived mixed surfactant microemulsions have not been reported earlier.

In this contribution, we report on a systematic investigation of phase behavior and solubilization of water in water-in-heptane or decane aggregates stabilized by mixtures of polyoxyethylene (20) cetyl ether (Brij-58) and cetyltrimethylammonium bromide (CTAB) surfactants with varying compositions in conjugation with 1-pentanol (Pn) at fixed surfactant(s)/Pn ratio and temperature. Synergism in water solubilization was evidenced by the addition of CTAB to Brij-58 stabilized system in close proximity of equimolar composition in both oils. An attempt has been made to correlate composition dependent water solubilization and volume induced conductivity studies to provide insight into the solubilization mechanism of these mixed systems. Conductivity studies reveal the ascending curve in water solubilization capacity-(Brij-58:CTAB, w/w) profile as the interdroplet interaction branch indicating percolation of conductance and the descending curve is a curvature branch due to the rigidity of the interface in these systems. The microstructure of these systems as a function of surfactant composition has been determined by dynamic light scattering (DLS) and Fourier transform infrared spectroscopy (FTIR) measurements. FTIR study reveals increase and decrease in relative population of bound and bulk-like water, respectively, with increase in Brij-58:CTAB (w/w). DLS measurements showed that the droplet hydrodynamic diameter (Dh) decreases significantly with the increase in Brij-58:CTAB (w/w). Further, the interfacial composition and energetic parameters for the transfer of Pn from bulk oil to the interface were evaluated by the dilution method. Formation of temperature-insensitive microemulsions and temperature invariant droplet sizes are evidenced in the vicinity of the equimolar composition. The results are interpreted in terms of a proposed mechanism.

Microemulsions (mEs), being thermodynamically stable, single phasic transparent mixtures of oil, water, surfactant ( either individually or in mixed state) and/or co-surfactant, are exemplary and multi dimensional reaction media in organic synthesis. They can act as an alternative of the phase transfer catalysis and influence the rate of the reaction due to the presence of charged carriers (amphiphiles) at the oil/water interface. The regioselectivity of many organic reactions can also be induced by employing mEs as templates. In particular, organic molecules with different degrees of polarity tend to accumulate at the oil/water interface of mEs. Subsequently, they orient themselves at the interface in such a way that the polar component extends into the water domain and the nonpolar component protrudes towards hydrocarbon domain. In view of this, a water-soluble reagent attacks the polar part of the amphiphile, and a reagent soluble in hydrocarbon reacts at the nonpolar part of the amphiphile. Because of this unique feature, use of mEs (or micro heterogeneous systems) as templates for studying organic reactions, have increased manifolds. In this short review, we mainly exemplify (i) mEs as reaction media, (ii) effect of microstructure of mEs on organic transformations and (iii) the most possible reaction location/site in mEs.

Absorption and emission spectroscopic studies, in combination with FTIR measurements, were carried out for 7-hydroxycoumarin (7HC) and nanocolloidal dispersion of silica. Attempt has been made to identify the characteristics of excited state H-bond formed between colloidal silica and 7HC in aqueous medium. Both the absorption and emission spectra of 7HC was found to be dependent on the concentration of silica. At lower silica concentrations, the absorption spectra decreases with increasing silica concentration, on the other hand, at higher concentration a bathochromic shift occurs in the absorption spectra of 7HC. Fluorescence behaviour followed the opposite trend in comparison to the absorption spectra. It is proposed that at lower silica concentration, excited state H-bond was formed between 7HC and silica dispersions. At higher concentration, the decrease in fluorescence intensity is attributed to the self quenching of adsorbed dye molecules over silica surface following the mechanism of Homo Forster resonance energy transfer (HFRET). Results were correlated with the size and surface charge of colloidal silica as measured by dynamic light scattering and zeta potential studies.

The present report focuses on the evaluation of the interfacial composition and the thermodynamics of the transfer of 1-pentanol (Pn) from a continuous oil phase to the interface of w/o nonionic microemulsion [Tween-20/Pn/cyclohexane(Cy)/water] in the absence and the presence of an ionic liquid (IL) (1-butyl-3-propylbenzimidazolium bromide) under different physicochemical conditions [viz. variation in concentrations of IL (0.0 → 0.20 mol dm−3) and temperature (293 → 323 K] at a fixed molar ratio of water to surfactant (ω) by the Schulman's method of cosurfactant titration at the oil/water interface. The overall transfer process has been found to be spontaneous, exothermic and organized in the absence or the presence of IL, but shown to be influenced by [IL]. The microstructure and state of water organization inside a pool of these systems have been characterized by different experimental techniques, e.g., conductivity, DLS and FTIR in the absence or the presence of IL. In addition, a C–C cross coupling reaction (Heck reaction) has been employed to explore the properties of IL (additive) in the confined environment of the microemulsion vis-a-vis its interaction with the constituents of the interface. The reaction progress has been monitored using the above techniques. The reaction ended with the highest yield (75%) in the presence of 0.05 mol dm−3 of IL, wherein the microemulsion forms spontaneously with the highest stability.