Solvent blends can control cationic reversed micellar interdroplet interactions. The effect of n-heptane:benzene mixture on BHDC reversed micellar interfacial properties: droplet sizes and micropolarity.

We have investigated, for the first time, the effect of the composition of the nonpolar organic media on the benzyl-n-hexadecyl-dimethylammonium chloride (BHDC) reversed micelles (RMs) properties at fixed temperature. To achieve this goal we have used the solvatochromic behavior of 1-methyl-8-oxyquinolinium betaine (QB) as absorption probe and dynamic light scattering (DLS), to monitor droplet sizes, interfacial micropolarity, and sequestrated water structure of water/BHDC/n-heptane:benzene RMs. DLS results confirm the formation of the water/BHDC/n-heptane:benzene RMs at every n-heptane mole fraction (X(Hp)) investigated, that is, X(Hp) = 0.00, 0.13, 0.21, 0.30, and 0.38. Also, DLS was used to measure the RMs diffusion coefficient and to calculate the apparent droplet hydrodynamic diameter (d(App)) at different compositions of the nonpolar organic medium. The data suggest that as the n-heptane content increases, the interdroplet attractive interactions also increase with the consequent increment in the droplet size. Moreover, the interdroplet attractive interactions can be "switched on (increased)" or "switched off (decreased)" by formulation of appropriate n-heptane:benzene mixtures. Additionally, QB spectroscopy was used to obtain the "operational" critical micellar concentration (cmc) and to investigate both the RMs interfacial micropolarity and the sequestrated water structure in every RMs studied. The results show that BHDC RMs are formed at lower surfactant concentration when n-heptane or water content increases. When the interdroplet interaction "switches on", the RMs droplet sizes growth expelling benzene molecules from the RMs interface, favoring the water-BHDC interaction at the interface with the consequent increases in the interfacial micropolarity. Therefore, changing the solvent blend is possible to affect dramatically the interfacial micropolarity, the droplet sizes and the structure of the entrapped water.

[1]  N. M. Correa,et al.  A new organized media: glycerol:N,N-dimethylformamide mixtures/AOT/n-heptane reversed micelles. The effect of confinement on preferential solvation. , 2011, The journal of physical chemistry. B.

[2]  N. M. Correa,et al.  Interfacial water with special electron donor properties: effect of water-surfactant interaction in confined reversed micellar environments and its influence on the coordination chemistry of a copper complex. , 2011, Journal of colloid and interface science.

[3]  F. Moyano,et al.  Cationic reverse micelles create water with super hydrogen-bond-donor capacity for enzymatic catalysis: hydrolysis of 2-naphthyl acetate by alpha-chymotrypsin. , 2010, Chemistry.

[4]  N. M. Correa,et al.  What are the factors that control non-aqueous/AOT/n-heptane reverse micelle sizes? A dynamic light scattering study. , 2009, Physical chemistry chemical physics : PCCP.

[5]  N. M. Correa,et al.  On the formation of new reverse micelles: a comparative study of benzene/surfactants/ionic liquids systems using UV-visible absorption spectroscopy and dynamic light scattering. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[6]  F. Moyano,et al.  Characterization of multifunctional reverse micelles' interfaces using hemicyanines as molecular probes. II: Effect of the surfactant. , 2009, The journal of physical chemistry. B.

[7]  K. Mutch,et al.  Control over microemulsions with solvent blends. , 2009, Langmuir : the ACS journal of surfaces and colloids.

[8]  K. Mutch,et al.  Effect of solvent quality on aggregate structures of common surfactants. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[9]  K. Mutch,et al.  Tuning aggregation of microemulsion droplets and silica nanoparticles using solvent mixtures. , 2008, Journal of colloid and interface science.

[10]  M. Drofenik,et al.  Reverse micelles: inert nano-reactors or physico-chemically active guides of the capped reactions. , 2007, Advances in colloid and interface science.

[11]  Na Li,et al.  Role of solubilized water in the reverse ionic liquid microemulsion of 1-butyl-3-methylimidazolium tetrafluoroborate/TX-100/benzene. , 2007, The journal of physical chemistry. B.

[12]  N. M. Correa,et al.  New insights on the photophysical behavior of PRODAN in anionic and cationic reverse micelles: from which state or states does it emit? , 2007, The journal of physical chemistry. B.

[13]  H. Iloukhani,et al.  Excess molar volumes and dynamic viscosities for binary mixtures of toluene + n-alkanes (C5-C10) at T= 298.15 K - : Comparison with Prigogine-Flory-Patterson theory , 2006 .

[14]  L. García‐Río,et al.  Influence of the Oil on the Properties of Microemulsions as Reaction Media , 2006 .

[15]  N. M. Correa,et al.  What can you learn from a molecular probe? New insights on the behavior of C343 in homogeneous solutions and AOT reverse micelles. , 2006, Journal of Physical Chemistry B.

[16]  T. Welton,et al.  Ionic liquid-in-oil microemulsions. , 2005, Journal of the American Chemical Society.

[17]  S. P. Moulik,et al.  Physicochemical Studies on Microemulsions. 8. The Effects of Aromatic Methoxy Hydrotropes on Droplet Clustering and Understanding of the Dynamics of Conductance Percolation in Water/Oil Microemulsion Systems , 2002 .

[18]  E. Lissi,et al.  Solubilization in AOT-water reverse micelles. Effect of the external solvent , 2002 .

[19]  Quan Li,et al.  Electrical Conductivity of Water/Sodium Bis(2-ethylhexyl) Sulfosuccinate/n-Heptane and Water/Sodium Bis(2-ethylhexyl) Phosphate/n-Heptane Systems: The Influences of Water Content, Bis(2-ethylhexyl) Phosphoric Acid, and Temperature. , 2001, Journal of colloid and interface science.

[20]  Silber,et al.  Influence of anionic and cationic reverse micelles on nucleophilic aromatic substitution reaction between 1-fluoro-2,4-dinitrobenzene and piperidine , 2000, The Journal of organic chemistry.

[21]  E. Lissi,et al.  INTERACTIONS OF SMALL MOLECULES WITH REVERSE MICELLES , 1999 .

[22]  N. M. Correa,et al.  Catalysis in Micellar Media. Kinetics and Mechanism for the Reaction of 1-Fluoro-2,4-dinitrobenzene with n-Butylamine and Piperidine in n-Hexane and AOT/n-Hexane/Water Reverse Micelles , 1999 .

[23]  S. P. Moulik,et al.  Microcalorimetric Investigation of AOT Self-Association in Oil and the State of Pool Water in Water/Oil Microemulsions , 1999 .

[24]  S. Pal,et al.  Solvation dynamics of 4-aminophthalimide in water-in-oil microemulsion of triton X-100 in mixed solvents , 1998 .

[25]  N. Levinger,et al.  Formamide in Reverse Micelles: Restricted Environment Effects on Molecular Motion , 1998 .

[26]  S. P. Moulik,et al.  Structure, dynamics and transport properties of microemulsions , 1998 .

[27]  N. Levinger,et al.  Novel Reverse Micelles Partitioning Nonaqueous Polar Solvents in a Hydrocarbon Continuous Phase , 1997 .

[28]  Z. A. Schelly,et al.  CPP-VPO, dynamic light scattering, and transient electric birefringence studies of reverse micellar aggregates of the separated p-tert-OPEn(n = 5, 7, and 9) components of Triton X-100 in cyclohexane , 1997 .

[29]  S. Egelhaaf,et al.  Droplet structure in phosphocholine microemulsions , 1997 .

[30]  D. Grand,et al.  Does the Interfacial Potential Control the Charge Separation Efficiency in Reverse Micellar Media , 1997 .

[31]  Silber,et al.  Micropolarity of Reversed Micelles: Comparison between Anionic, Cationic, and Nonionic Reversed Micelles , 1996, Journal of colloid and interface science.

[32]  G. Onori,et al.  Micellar interactions in water-in-oil microemulsions , 1996 .

[33]  Jinfeng Dong,et al.  Mixing of alkanes with surfactant monolayers in microemulsions , 1996 .

[34]  Jinfeng Dong,et al.  Structure in microemulsions of di-chained surfactants , 1996 .

[35]  S. P. Moulik.  MICELLES : SELF-ORGANIZED SURFACTANT ASSEMBLIES , 1996 .

[36]  A. Maitra,et al.  Solution behaviour of Aerosol OT in non-polar solvents , 1995 .

[37]  N. M. Correa,et al.  Micropolarity of Reverse Micelles of Aerosol-OT in n-Hexane , 1995 .

[38]  S. P. Moulik,et al.  Thermodynamics of micellization of aerosol OT in polar and nonpolar solvents. A calorimetric study , 1993 .

[39]  Y. Marcus,et al.  The properties of organic liquids that are relevant to their use as solvating solvents , 1994 .

[40]  Z. A. Schelly,et al.  Reverse micelles and water in oil microemulsions of triton X-100 in mixed solvents of benzene and n-hexane. Dynamic light scattering and turbidity studies , 1992 .

[41]  Z. A. Schelly,et al.  Reverse micelles of triton X-100 in cyclohexane. Effects of temperature, water content, and salinity on the aggregation behavior , 1992 .

[42]  A. Jada,et al.  Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents. 2. Droplet sizes and interactions and exchange of material between droplets , 1990 .

[43]  A. Jada,et al.  Ternary water in oil microemulsions made of cationic surfactants, water, and aromatic solvents. 1. Water solubility studies , 1990 .

[44]  Z. A. Schelly,et al.  Reverse micelles of Aerosol-OT in benzene. 4. Investigation of the micropolarity using 1-methyl-8-oxyquinolinium betaine as a probe , 1989 .

[45]  Z. A. Schelly,et al.  Controlled partial pressure-vapor pressure osmometry (CPP-VPO). A new method for the characterization of reverse micelles and W O microemulsions , 1988 .

[46]  D. Shah,et al.  A light scattering study on the droplet size and interdroplet interaction in microemulsions of AOT—oil—water system , 1988 .

[47]  F. Heatley.  A 1H nuclear magnetic resonance chemical-shift study of inverted microemulsions of aerosol OT in benzene and cyclohexane. Partitioning of water between hydrocarbon and aqueous phases , 1988 .

[48]  B. Robinson,et al.  The kinetics of solubilisate exchange between water droplets of a water-in-oil microemulsion , 1987 .

[49]  Barry W. Ninham,et al.  Molecular forces in the self-organization of amphiphiles , 1986 .

[50]  S. Costa,et al.  Interactions of excited-state porphyrin–quinone in reversed micelles studied by time-resolved fluorescence spectroscopy , 1986 .

[51]  John S. Huang.  Surfactant interactions in oil continuous microemulsions , 1985 .

[52]  A. Maitra.  Determination of size parameters of water-Aerosol OT-oil reverse micelles from their nuclear magnetic resonance data , 1984 .

[53]  G. Grest,et al.  Attractive Interactions in Micelles and Microemulsions , 1984 .

[54]  B. Robinson,et al.  Structural study of aerosol-OT-stabilised microemulsions of glycerol dispersed in n-heptane , 1984 .

[55]  D. Roux,et al.  Micellar interactions in water-in-oil microemulsions. 1. Calculated interaction potential , 1983 .

[56]  G. Fourche,et al.  Micellar interactions in water-in-oil microemulsions. 2. Light scattering determination of the second virial coefficient , 1983 .

[57]  J. K. Thomas,et al.  Benzylhexadecyldimethylammonium chloride in microemulsions and micelles , 1981 .

[58]  D. Langevin,et al.  Diffusion of interacting particles: Light scattering study of microemulsions , 1981 .

[59]  J. Fendler.  Interactions and reactions in reversed micellar systems , 1976 .