Increasing NaBr Concentration Research Articles

Polysulfobetaines in Aqueous Solution and in Thin Film Geometry.

Polysulfobetaines in aqueous solution show upper critical solution temperature (UCST) behavior. We investigate here the representative of this class of materials, poly (N,N-dimethyl-N-(3-methacrylamidopropyl) ammonio propane sulfonate) (PSPP), with respect to: (i) the dynamics in aqueous solution above the cloud point as function of NaBr concentration; and (ii) the swelling behavior of thin films in water vapor as function of the initial film thickness. For PSPP solutions with a concentration of 5 wt.%, the temperature dependence of the intensity autocorrelation functions is measured with dynamic light scattering as function of molar mass and NaBr concentration (0–8 mM). We found a scaling of behavior for the scattered intensity and dynamic correlation length. The resulting spinodal temperatures showed a maximum at a certain (small) NaBr concentration, which is similar to the behavior of the cloud points measured previously by turbidimetry. The critical exponent of susceptibility depends on NaBr concentration, with a minimum value where the spinodal temperature is maximum and a trend towards the mean-field value of unity with increasing NaBr concentration. In contrast, the critical exponent of the correlation length does not depend on NaBr concentration and is lower than the value of 0.5 predicted by mean-field theory. For PSPP thin films, the swelling behavior was found to depend on film thickness. A film thickness of about 100 nm turns out to be the optimum thickness needed to obtain fast hydration with H2O.

Dilute nitric or nitrous acid solution containing halide ions as effective media for pure gold dissolution.

The greatly enhanced oxidation ability of dilute aqueous nitric acid (0.10-2.0 mol L(-1)) containing bromide and iodide salts as well as chloride salts has been examined based on the dissolution kinetics of pure gold at 30-60 °C. It has been found that bromide salts are more effective than chloride salts in gaining the ability of dissolving gold in dilute aqueous nitric acid solution. At 60 °C, a piece of gold-wire (ca. 20 mg) is dissolved in 20 mL of as low as 0.10 mol L(-1) HNO3 solution containing 1.0-5.0 mol L(-1) NaBr and the dissolution rate constant, log(k/s(-1)), increases linearly (from -5.78 to -4.52) with the increasing NaBr concentration. The addition of organic solvents, such as acetonitrile and acetic acid, causes acceleration of gold dissolution in LiBr and NaBr solutions. With increasing MeCN contents, for instance, the log(k/s(-1)) value of 0.10 mol L(-1) HNO3 solution containing 2.0 mol L(-1) NaBr increases linearly from -5.30 to -4.61 at 30% (v/v) MeCN. The bromide salts affect the gold dissolution rate constant in the order of KBr < NaBr < LiBr < CaBr2. With increasing NaI concentration (0.20-3.0 mol L(-1)), some acceleration in log(k/s(-1)) of 0.50 or 1.0 mol L(-1) HNO3 solution has been observed; however, the slope of acceleration as the function of NaI concentration is much smaller than that of NaCl or NaBr. The gold dissolution ability has been examined also for nitrous acid containing chloride and bromide ions at 35 °C. The NaNO2 solution containing twice or more amounts of HX (X = Cl, Br) gives the maximum efficiency for gold dissolution, according to the log(k/s(-1)) values of the mixed solutions of NaNO2 (0.10-2.0 mol L(-1)) and HX of various concentrations. The influence of oxidation by dilute nitric and nitrous acids on the gold dissolution is discussed from the standpoint of the redox potentials in "modified" aqueous solutions and not of the changes in the activity coefficients of ions.

Phase equilibria of quaternary system NaCl-NaBr-Na2B4O7-H2O at 348 K

The phase equilibria of quaternary system NaCl-NaBr-Na2B4O7-H2O at 348 K were studied by the isothermal equilibrium method. The solubilities and densities of the equilibrium solution were determined. According to the experimental data, the phase diagram, density-composition diagrams and water content diagram of the quaternary system at 348 K were plotted respectively. And the phase diagram consists of one univariant curve, two crystallization fields and without any invariant point of the quaternary system. The equilibrium solid phases of the two crystallization fields were Na(Cl, Br) and Na2B4O7·5H2O. The experimental results show that the quaternary system contained solid solution. The densities of the solution decrease with increasing NaCl concentration and increase with increasing NaBr concentration.

Application of Microelectrode Voltammetry to Study the Properties of Surfactant Solutions: Alkyltrimethylammonium Bromides

Microelectrode cyclic voltammetry (MV) has been employed to investigate the micellar properties of solutions of homologous alkyltrimethylammonium bromides, RMe(3)ABr, R = C(10), C(12), and C(14), in water and in the presence of added NaBr. The micellar self-diffusion coefficient was calculated from the limiting current for the reversible electron transfer of micelle-bound ferrocene. From the values of this property, other parameters were calculated, including the micellar hydrodynamic radius, R(H), and aggregation number, N(agg); the latter was also theoretically calculated. We determined the values of the diffusion coefficient as a function of various experimental variables and observed the following trends: The diffusion coefficient decreases as a function of increasing surfactant concentration (no additional electrolyte added); it decreases as a function of increasing surfactant concentration at fixed NaBr concentration; and it shows a complex dependence (increase then decrease) on the NaBr concentration at a fixed RMe(3)ABr concentration. The value of the intermicellar interaction parameter decreases and then increases as a function of increasing NaBr concentration. These results are discussed in terms of intermicellar interactions and the effect of NaBr on the micellar surface charge density and sphere-to-rod geometry change. The NaBr concentration required to induce the latter change increases rapidly as a function of decreasing the length of R: no geometry change was detected for C(10)Me(3)ABr. Values of N(agg) increase as a function of increasing the length of R and are in good agreement with both literature values and values that were calculated theoretically. Thus, MV is a convenient and simple technique for obtaining fundamental properties of surfactant solutions, including additive-induced changes of micellar parameters (N(agg)) and morphology changes.

Light Scattering Studies of Amphiphilic Drugs Promethazine Hydrochloride and Imipramine Hydrochloride in Aqueous Electrolyte Solutions

Two amphiphilic drugs, promethazine hydrochloride (PMT) and imipramine hydrochloride (IMP), have been studied using both static and dynamic light scattering techniques. Due to having rigid tricyclic hydrophobic moieties in their molecules, these drugs show interesting association behavior. The static light scattering (SLS) measurements show that the self-association commenced above a well-defined critical micellar concentration ( cmc), which decreases with increasing NaBr concentration. The Gibbs energy of micellization, DeltaG(0)M, in all cases, is negative. The colloidal stability of the system in terms of the interparticle interaction at different NaBr concentrations was studied using the dynamic light scattering (DLS) technique. The experimentally evaluated interparticle interaction parameter ( k D ) was compared with the Derjaguin-Landau-Verwey-Overbeek (DLVO) model. Interestingly, these two drugs with similar molecular structure show difference in their interparticle interactions, e.g., PMT showed complete agreement with the DLVO model whereas IMP showed clear deviation from this model at lower concentrations and agreement at higher concentrations of NaBr.

Salt effect on the complex formation between cationic gemini surfactant and anionic polyelectrolyte in aqueous solution.

Salt effect on the interaction of anionic polyelectrolyte sodium carboxymethylcellulose (NaCMC) with cationic gemini surfactant hexamethylene-1,6-bis(dodecyldimethylammonium bromide) [C12H25(CH3)2N(CH2)6N(CH3)2C12H25]Br2 (C12C6C12Br2) has been investigated using turbidimetric titration, steady-state fluorescence, and mobility measurement. It is found that the critical aggregation concentration(cac) for C12C6C12Br2/NaCMC complexes depends little on addition of sodium bromide (NaBr). However, in the presence of nonionic surfactant Triton X-100 (TX100), the critical ionic surfactant mole fraction for the onset of complex formation (Yc) increases markedly with increasing NaBr concentration. These salt effects are supposed as the overall result from competition between the increase of interaction and the screening of interaction. The increase of interaction is referred to as the effect that the larger micelle with higher surface charge density induced by salt has a stronger interaction with oppositely charged polyelectrolyte. The screening of interaction is referred to as the salt screening of electrostatic attraction between the polymer chain and the surfactant. For complex formation between C12C6C12Br2 and NaCMC, the increase of interaction probably compensates the screening of interaction, leading to constant cac values at different salt concentrations. For complex formation between the C12C6C12Br2/TX100 mixed micelle and NaCMC, the screening of interaction probably plays a dominant role, leading to higher suppression of electrostatic binding of micelles to polyelectrolyte.

Solubilization of a water-insoluble dye in aqueous NaBr solutions of alkylpyridinium bromides and its relation to micellar size and shape

In order to investigate the effect of added salt on micelle size, shape, and structure the solubilization of Orange OT in aqueous NaBr solutions of decylpyridinium bromide (DePB), dodecylpyridinium bromide (DPB), tetradecylpyridinium bromide (TPB), and hexadecylpyridinium bromide (CPB) has been examined. The solubilization powers of DePB and DPB micelles increase with increasing NaBr concentration up to 2.86 and 3.07 mol dm–3, respectively, but above these concentrations remain unaltered. This suggests that spherical micelles of DePB and DPB can have a maximum and constant size at NaBr concentrations higher than these threshold concentrations. On the other hand, the solubilization powers of TPB and CPB micelles increase in the whole range of NaBr concentration studied. The dependencies of the solubilization powers of their micelles on the counterion concentration change at 0.10 and 0.03 mol dm–3 NaBr, respectively, as suggests that TPB and CPB micelles undergo the sphere–rod transition at those concentrations. Orange OT is a more suitable probe for detecting the presence of the maximum- and constant-size spherical micelle than Sudan Red B.

Effect of Temperature on Micelle Formation in Aqueous NaBr Solutions of Octyltrimethylammonium Bromide

Association processes in aqueous solutions of octyltrimethylammonium bromide, C8TAB, have been studied in aqueous NaBr solutions at temperatures from 20 to 55°C. The values of the critical micelle concentration, CMC, were determined from the intersections of two straight line portions of the plots of the relationship between adiabatic compressibility of the solutions and surfactant concentration. The value of the CMC thus determined exhibits minima at a certain temperature, Tmin. The value of Tmin shifts toward a lower temperature with increasing NaBr concentration. Based on the most probable micelle size model, the values of thermodynamic functions of micelle formation have been estimated at various temperatures.

Fluorescence and Conductivity Studies of Polyelectrolyte-Induced Aggregation of Alkyltrimethylammonium Bromides

Micelle formation of alkyltrimethylammonium surfactants (CnTMAB) in aqueous sodium poly(styrenesulfonate) (NaPSS) solutions was studied by fluorescence and conductivity measurements at 25 °C. The dependence of the aggregation phenomena on the chain length of the surfactant (n = 12, 14, 16, 18) and on the ionic strength of solutions was investigated. The critical aggregation concentration (cac) decreases with increasing hydrophobicity of the surfactant but remains approximately unchanged for C16TMAB and C18TMAB. The cac values are considerably lower than the critical micellization concentration (cmc) values for the same surfactant. The decrease is in the range from about three orders of magnitude for C12EDMAB in water to approximately 10 times for C18TMAB in 0.01 M NaBr. Furthermore, the cac for C12EDMAB and C14TMAB in NaPSS was found to increase slightly with increasing NaBr concentration but much less than, for instance, in sodium poly(acrylate) solutions. No significant effect of NaBr on cac values for C16TMAB and C18TMAB was found. The relatively weak dependence of cac on the surfactant chain length and on the simple salt concentration can be explained by the formation of a very stable aggregate between the polyelectrolyte and the amphiphile via the inclusion of aromatic side groups on the polymer chain into the surface of the micelle-like surfactant aggregate. Measurements of electrolytic conductivity showed that the mobility of the surfactant ions is greatly reduced in the presence of oppositely charged polyion. The surfactant preferentially forms the complex with the polyelectrolyte. When the complexation is complete free micelles appear in the system at the apparent critical micellization concentration (cmc*), which is therefore slightly higher in polyelectrolyte solutions than the ordinary cmc in pure surfactant solutions.

The Salt-Induced Sphere–Rod Transition of Micelles of 1-Tetradecylpyridinium Bromide in Aqueous NaBr Solutions

Abstract Static light scattering from aqueous NaBr solutions of 1-tetradecylpyridinium bromide (TPB) has been measured over the range of NaBr concentrations from 0 to 0.50 mol dm−3 at 25 °C, and the micelle molecular weight has been estimated. For 0—0.20 mol dm−3 NaBr, the reduced intensity of scattered light does not show any angular dependence, and the molecular weight of the spherical micelle of TPB slightly increases from 27.6 × 103 to 41.4 × 103 with increasing NaBr concentration. Beyond 0.20 mol dm−3 NaBr, the angular dissymmetry of the reduced scattering intensity and a steep increase in the micelle molecular weight from 41.4 × 103 to 177.8 × 103 are observed. Therefore, TPB has been considered to form rodlike micelles. The linear double logarithmic relationship between molecular weight and ionic strength holds for spherical and rodlike micelles, respectively. From the intersection of these two lines, the threshold NaBr concentration for the sphere-rod trainsition of TPB micelle is estimated to be 0.19 mol dm−3, where the micelle has a molecular weight of 41.3 × 103.

Effects of hydroxide ion, salts and temperature on the hydrolytic cleavage of ionized N-hydroxyphthalimide (NHPH) in the presence of cationic micelles

The effects of cetytrimethylammonium bromide (CTABr) micelles on pseudo first-order rate constants ( k obs) for the alkaline hydrolysis of N-hydroxyphthalimide (NHPH) have been studied at different NaOH and NaBr concentrations. Pseudo first-order rate constants were treated with a pseudo-phase ion-exchange model of micelles. The rate constants for micellar-mediated reactions are independent of NaBr concentration, while the binding constant of anionic NHPH with CTABr miceles decreases with increasing NaBr concentration. The rate of reaction in the micellar pseudo-phase is significantly smaller than that in the aqueous pseudo-phase. The effects of KBr and KCl concentration on k obs at constant CTABr and NaOH concentrations reveal that an increase in KBr or KCl concentration causes the expulsion of micellized anionic NHPH molecules (NHP M −) from the micellar pseudo-phase to the aqueous pseudo-phase. Bromide ions expel NHP M − more strongly than chloride ions.

The effect of added salt on adsorption and adsolubilization by a gemini surfactant on silica

Adsorption of a dimeric (1,2-bis(dodecyldimethylammonio) ethane dibromide, 2RenQ) on silica from its aqueous solution has been investigated in presence of added NaBr. The adsorbed amounts of 2RenQ at saturation increase with increasing amount of NaBr added. The dispersion stability of silica suspensions caused by adsorption of 2RenQ is well correlated with the change in ξ potentials. With a constant feed concentration of 2-naphthol, the adsolubilized amounts of 2-naphthol are greater when NaBr is added, but the ratios of adsolubilized amount of 2-naphthol/adsorbed amount of 2RenQ at maximum adsolubilization decrease with increasing NaBr concentration. This result is interpreted by the change in microviscosity of the 2RenQ adsorbed layer, as estimated by the ESR probe technique. In addition, from a two-step process of adsorption-adsolubilization, it is found that 2RenQ adsorbs on silica much more strongly in presence of added NaBr, keeping 2-naphthol in the adsorbed layers, than when NaBr is not added.

Solubilization of a Water-Insoluble Dye in Aqueous Sodium Halide Solutions of Dodecylpyridinium Halides: Effects of Counterion Species of Ionic Micelles

Abstract Solubilization of Sudan Red B in aqueous micellar solutions of dodecylpyridinium chloride (DPC) in the presence of NaCl from 0 to 4.00 M and of dodecylpyridinium bromide (DPB) in the presence of NaBr from 0 to 6.00 M has been examined to investigate the effects of added salt, i.e., micelle size, shape, and structure, The DPC micelles have solubilization power, 2.08 × 10 -3 mol per mole micellar DPC, over the range of 0 to 4.00 M NaCl. The constant solubilization power of DPC, independent of its micelle species, either porous at lower NaCl concentrations or spherical at higher NaCl concentrations, suggests that the solubilization locus of a spherical micelle locates near its polar or outer parts. The DPB micelles have solubilization power, 2.26 × 10 -3 mol per mole micellar DPB, in the range from 0 to 3.12 M NaBr, where the formation of spherical micelles and their mutual repulsive or no mutual interaction in solution has been confirmed by light-scattering measurements. At higher NaBr concentrations where spherical micelles formed, the critical micelle concentrations are subject to mutual attractive interaction; at finite micelle concentrations, the solubilization power increases with increasing NaBr concentration, in such a way that it behaves characteristically as if rodlike micelles are formed.

Solubilization of spiropyran in aqueous NaBr solutions of dodecyltrimethylammonium bromide

1,3,3-Trimethylindolino-6′-nitrobenzopyrilospiran is solubilized in aqueous NaBr solutions of dodecyltrimethylammonium bromide (DTAB). The dye is soluble in solutions of DTAB having concentrations higher than the critical micelle concentration. The solubilization power of DTAB is 2.08·10 −3 mol dye per mol DTAB at NaBr concentrations lower than 1.84 M, while it increases linearly with increasing NaBr concentration from 1.84–4.50 M. The constant solubilization power of DTAE is attributable to the spherical micelles, while its higher solubilization power in the presence of NaBr beyond 1.84 M can be ascribed to rod-like micelles. The solubilization capacity of a spherical micelle of DTAB ranges from 0.11–0.18, depending on the NaBr concentration, where the micelle aggregation number varies from 52–86. The rod-like micelle has an increasing solubilization capacity with increasing NaBr concentration, and it can solubilize the dye to such an amount that 136 DTAB molecules along its contour length incorporate one dye molecule. The solubilized dye is partly in the mecrocyanine form, and the solubilization locus has polarity corresponding to a dielectric constant ≈35.

Effect of temperature on the salt-induced sphere–rod transition of micelles of dodecyltrimethylammonium bromide in aqueous NaBr solutions

The density of aqueous NaBr solutions of dodecyltrimethylammonium bromide (C12TAB) and ultrasound velocity in them have been measured as a function of surfactant concentration at NaBr concentrations 0–5.00 mol kg–1 and at temperatures 15–50 °C. Their adiabatic compressibility has been calculated by means of the Laplace equation. Based on a phenomenological treatment giving the density and the adiabatic compressibility of aqueous solutions of surfactant as a function of surfactant concentration, the apparent adiabatic compressibility of the surfactant in the form of spherical and rod-like micelles has been derived at different NaBr concentrations and at different temperatures.The apparent molar volume of the surfactant in the rod-like micelle is slightly larger than that in the spherical micelle at each temperature. The apparent adiabatic compressibility of the surfactant in the spherical micelle initially decreases upon addition of a small amount of NaBr, and then it remains constant or slightly increases with further addition of NaBr. The apparent adiabatic compressibility of the surfactant in the rod-like micelle increases with increasing NaBr concentration at each temperature, with an abrupt change at the threshold.The threshold NaBr concentration for the sphere–rod transition of the surfactant can be determined from variation of the apparent adiabatic compressibility of the surfactant in the micellar forms with NaBr concentration. It increases with rising temperature and changes from 1.64 mol kg–1 at 20 °C to 2.86 mol kg–1 at 45 °C.The initiation of the sphere–rod transition of micelles is attributed to a change in the hydration state of the surfactant with the NaBr concentration, and the threshold NaBr concentration is defined by the chemical potential of water in solution, with which hydration water on spherical and rod–like micelles are in equilibrium and where the hydration water has an equal escaping tendency on both micelles.

The salt-induced sphere-rod transition of micelles of dodecyltrimethylammonium bromide in aqueous NaBr solutions as studied by the ultrasound velocity measurements

The density and adiabatic compressibility of aqueous NaBr solutions of dodecyltrimethylammonium bromide have been determined by means of pycnometry and ultrasound velocity measurements at 25°C. Phenomenological equations of density and adiabatic compressibility of micellar solutions have been given as functions of the concentration of the spherical micelle, to which the apparent molar volume and the apparent adiabatic compressibility are assigned. These equations have been further extended in such a way to be applicable for solutions containing both spherical and rod-like micelles, by introducing the apparent molar volume and the apparent adiabatic compressibility of a rod-like micelle. In the actual application of the present treatment, the concentration of the rod-like micelle has been obtained as a function of total micelle concentration by referring to the previous results of light scattering. Actually the density and adiabatic compressibility have changed linearly with total micelle concentration, even in the presence of both kinds of micelles. In this way the apparent molar volumes and the apparent adiabatic compressibilities of dodecyltrimethylammonium bromide in both spherical and rod-like micelles have been derived. Its apparent molar volume is slightly larger for the rod-like micelle than for the spherical one. Its apparent adiabatic compressibility is negative in the monomeric form, and its apparent adiabatic compressibility in spherical micelles changes in a somewhat complicated way with increasing NaBr concentration, while that in rod-like micelles increases less sharply with increasing NaBr concentration.

Solubilization of a water-insoluble dye in aqueous solutions of dodecyltrimethylammonium halides, and its relation to micelle size and shape

The solubilization properties of aqueous sodium halide solutions of dodecyltrimethylammonium halides have been measured for a water-insoluble dye, Sudan Red B, and they are related to the micelle size and shape, by referring to the molecular weight data already reported. The solubilization power of micellar solutions of dodecyltrimethylammonium chloride toward Sudan Red B is 2.8 × 10 −3 mole of dye per mole of surfactant, independent of the NaCl concentration up to 4.0 M, where only spherical micelles are formed. The solubilization power of micellar solutions of dodecyltrimethylammonium bromide slightly increases with increasing NaBr concentration and abruptly increases from 2.9 × 10 −3 to 3.9 × 10 −3 mole of dye per mole of surfactant, at 1.0–1.5 M NaBr, corresponding to the sphere-rod transition. The solubilization power of dodecyltrimethylammonium bromide is higher in rodlike micelles than in spherical micelles. The solubilization capacity of a spherical micelle composed of dodecyltrimethylammonium ions is nearly independent of counterion species, either chloride or bromide ion. The solubilization capacities of both spherical and rodlike micelles increase with their size almost linearly. From the density measurements of aqueous solutions of dodecyltrimethylammonium halides, the partial molar volume of surfactants is derived, and it is found that dodecyltrimethylammonium ions have an equal contribution to the partial molar volume of surfactant. The packing state of dodecyltrimethylammonium ions in micelles is common for both surfactants, and also for spherical and rodlike micelles.

Formation of spherical and rod-like micelles of cetyltrimethylammonium bromide in aqueous NaBr solutions

Static light scattering from aqueous NaBr solutions of cetyltrimethylammonium bromide (CTAB) has been measured at 35°C with 488-nm laser light, and the molecular weight, radius of gyration, and the other parameters of its micelles have been evaluated. In water, spherical micelles are formed above a critical micelle concentration, 0.04 × 10 −2 g cm −3, and each micelle consists of 91 monomers of CTAB. In aqueous solutions having NaBr concentrations higher than 0.06 M, rod-like micelles are formed, besides spherical micelles. The molecular weight of rod-like micelles increases rapidly with increasing NaBr concentration. The rod-like micelle formed in 0.5 M NaBr has molecular weight as high as 3,470,000, and is considerably flexible. The persistence length of micelle is evaluated to be 44 nm. Electron micrographic observations have been carried out for specimens prepared from CTAB solutions in water and in 0.5 M NaBr at 35°C. A specimen prepared from aqueous solution of CTAB and negatively stained with uranyl acetate displays many globular images, which have a uniform diameter around 5–6 nm and can be assigned to spherical micelles. A specimen from 0.5 M NaBr solution shows tortuous thread-like images with a uniform diameter of 4.5–6 nm, which can be regarded as flexible rod-like micelles. Thus, the size and shape of spherical and rod-like micelles of CTAB observed by the light-scattering measurement are confirmed by electron microscopy.

The sphere-rod transition of micelles of dodecyldimethylammonium bromide in aqueous NaBr solutions, and the effects of counterion binding on the micelle size, shape and structure

Micelle size and shape of dodecyldimethylammonium bromide have been determined by measurement of light scattering from its aqueous NaBr solutions. In water and in the presence of NaBr up to 0.07 M, the Debye plots give straight lines with positive slopes, and spherical micelles having molecular weight less than 30 000 are formed. At higher NaBr concentrations, the Debye plots decrease with increasing micelle concentration, indicating the aggregation of the primary spherical micelles into larger secondary micelles. The molecular weight and the radius of gyration of the secondary micelles increase with increasing NaBr concentration, and the relation between molecular weight and radius of gyration suggests that they are rodlike and flexible. Linear logarithmic relations between micelle molecular weight and ionic strength hold for spherical and rodlike micelles, respectively, and the threshold concentration of NaBr for the sphere-rod transition is located at 0.07 M. The spherical micelle of dodecyldimethylammonium ions has a size more than 20 surfactant ions larger in NaBr solutions than in NaCl solutions, and their rodlike micelle has a shorter length in NaBr solutions than in NaCl solutions, when compared at an identical aggregation number, indicating 2 more surfactant ions in its cross-section.

Effect of sorbed water on dielectric and mechanical properties of polyion complex

AbstractEffect of sorbed water on dielectric and mechanical properties is studied for three kinds of polyion complex (PIC) membranes formed from equal moles of polyanion [poly(sodium 4‐vinylbenze‐sulfonate)] and three polycations of different structural isomerisms [poly(4‐vinylphenethyltriethylammonium bromide), poly(3‐vinylphenethyltriethylammonium bromide), and random copolymer of these monomers]. Sorption isotherms and swelling characteristics indicate that PIC of parapolycation includes more water microphases than PIC of meta‐polycatio. Complex dielectric constants of three PICs with varied water contents are measured at frequencies from 10 Hz to 100 kHz and the relaxation is analyzed in terms of the heterogeneous structure. Stress–elongation relationships of PICs equilibrated with water and aqueous NaBr indicate that yield and break stresses are higher for PIC of meta‐polycation than that of para‐polycation and decrease with increasing NaBr concentration above 0.1M.